feat: integrate Solid source and three-DOF semantics

include/fesa/assembly/load_assembler.h

@@ -13,17 +13,21 @@ namespace fesa {
 class LoadAssembler {
  public:
   /// @brief Accumulates all active CLOAD rows in full-DOF space.
+  /// @param step_time Actual finite nonnegative dynamic endpoint for amplitude.
   /// @return A finite full load vector or a structured model failure.
   static Result<Vector> AssembleFullNodalLoad(const AnalysisModel& model,
-                                              const DofManager& dofs);
+                                              const DofManager& dofs,
+                                              double step_time = 0.0);
 
   /// @brief Accumulates explicitly supplied loads in their view order.
   /// @param loads Non-owning loads whose contribution source orders must match
   /// their view positions.
+  /// @param step_time Actual finite nonnegative dynamic endpoint for amplitude.
   /// @return A candidate committed only after all contributions validate.
   static Result<Vector> AssembleFullNodalLoad(const AnalysisModel& model,
                                               const DofManager& dofs,
-                                              const LoadView& loads);
+                                              const LoadView& loads,
+                                              double step_time = 0.0);
 
   /// @brief Forms Ff-Kfc*dc in stable free/constrained order.
   /// @note This operation neither factorizes nor invokes a solver.

include/fesa/elements/element_definition.h

@@ -9,7 +9,12 @@
 namespace fesa {
 
 /// @brief Identifies the supported semantic element-definition kinds.
-enum class ElementDefinitionKind { kEulerBeam3D, kMitc4Shell, kDs4Thermal };
+enum class ElementDefinitionKind {
+  kEulerBeam3D,
+  kMitc4Shell,
+  kDs4Thermal,
+  kHex8
+};
 
 /// @brief Provides immutable source identity and topology for one element.
 /// @note Numerical stiffness, recovery, and equation ids are intentionally

include/fesa/elements/hex8_definition.h

@@ -0,0 +1,58 @@
+#ifndef FESA_ELEMENTS_HEX8_DEFINITION_H_
+#define FESA_ELEMENTS_HEX8_DEFINITION_H_
+
+#include <array>
+#include <utility>
+#include <vector>
+
+#include "fesa/elements/element_definition.h"
+
+namespace fesa {
+/// @brief Owns source-safe eight-node Solid topology without numerical state.
+class Hex8Definition final : public ElementDefinition {
+ public:
+  /// @brief Constructs a semantic candidate in source connectivity order.
+  Hex8Definition(SourceEntityId source, std::array<EntityIndex, 8> nodes,
+                 EntityIndex material, EntityIndex section,
+                 SourceLocation source_location)
+      : source_id{std::move(source)},
+        node_indices{nodes},
+        material_index{material},
+        section_index{section},
+        location{std::move(source_location)},
+        property_index_{section},
+        node_indices_view_{nodes.begin(), nodes.end()} {}
+  ElementDefinitionKind Kind() const noexcept override {
+    return ElementDefinitionKind::kHex8;
+  }
+  const SourceEntityId& SourceId() const noexcept override { return source_id; }
+  std::string_view SourceElementType() const noexcept override {
+    return "C3D8";
+  }
+  const std::vector<EntityIndex>& NodeIndices() const noexcept override {
+    return node_indices_view_;
+  }
+  EntityIndex MaterialIndex() const noexcept override { return material_index; }
+  EntityIndex PropertyIndex() const noexcept override {
+    return property_index_;
+  }
+
+  SourceEntityId source_id;
+  std::array<EntityIndex, 8> node_indices;
+  EntityIndex material_index;
+  EntityIndex section_index;
+  SourceLocation location;
+
+ private:
+  friend class Domain;
+  /// @brief Synchronizes candidate topology with the immutable base view.
+  void SynchronizeNodeIndices() {
+    node_indices_view_.assign(node_indices.begin(), node_indices.end());
+  }
+  /// @brief Binds the local Solid section to the unified property collection.
+  void SetPropertyIndex(EntityIndex index) noexcept { property_index_ = index; }
+  EntityIndex property_index_;
+  std::vector<EntityIndex> node_indices_view_;
+};
+}  // namespace fesa
+#endif  // FESA_ELEMENTS_HEX8_DEFINITION_H_

include/fesa/fem/dof_manager.h

@@ -16,8 +16,8 @@ namespace fesa {
 
 class DofManagerTestAccess;
 
-/// @brief Distinguishes structural six-component and thermal five-station maps.
-enum class DofProfile { kStructural, kThermal };
+/// @brief Distinguishes six-component, Solid translation, and thermal maps.
+enum class DofProfile { kStructural, kThermal, kSolidStructural };
 
 /// @brief Stores the stable full-space CSR pattern.
 struct SparsePattern {
@@ -59,6 +59,8 @@ class DofManager {
 
   /// @brief Reports which physical component profile owns this mapping.
   DofProfile Profile() const noexcept;
+  /// @brief Returns the physical component count for the active profile.
+  std::size_t ComponentsPerNode() const noexcept;
 
   /// @brief Returns the full node-by-component DOF count.
   std::size_t FullDofCount() const noexcept;

include/fesa/loads/concentrated_nodal_load.h

@@ -3,6 +3,8 @@
 
 #include <array>
 #include <cstddef>
+#include <optional>
+#include <string>
 
 #include "fesa/core/diagnostic.h"
 #include "fesa/loads/load.h"
@@ -21,7 +23,10 @@ class ConcentratedNodalLoad final : public Load {
   /// @brief Creates one parsed CLOAD component while preserving diagnostics.
   ConcentratedNodalLoad(SourceTargetQuery target, int source_dof,
                         double magnitude, std::size_t source_order,
-                        SourceLocation location);
+                        SourceLocation location,
+                        std::optional<EntityIndex> amplitude_index = {},
+                        std::string amplitude_name_raw = {},
+                        SourceLocation amplitude_location = {});
 
   /// @brief Computes target-major, component-minor full-DOF contributions.
   Result<std::vector<LoadContribution>> ComputeContributions(
@@ -39,12 +44,28 @@ class ConcentratedNodalLoad final : public Load {
   /// @brief Returns the source location used by structured diagnostics.
   const SourceLocation& Location() const noexcept;
 
+  /// @brief Returns a model-level amplitude index when one was specified.
+  std::optional<EntityIndex> AmplitudeIndex() const noexcept {
+    return amplitude_index_;
+  }
+  /// @brief Returns preserved CLOAD amplitude option spelling.
+  const std::string& AmplitudeName() const noexcept {
+    return amplitude_name_raw_;
+  }
+  /// @brief Returns the source location of the CLOAD amplitude option.
+  const SourceLocation& AmplitudeLocation() const noexcept {
+    return amplitude_location_;
+  }
+
  private:
   SourceTargetQuery target_;
   std::array<double, 6> global_components_{};
   std::size_t source_order_;
   SourceLocation location_{};
   int source_dof_{0};
+  std::optional<EntityIndex> amplitude_index_;
+  std::string amplitude_name_raw_;
+  SourceLocation amplitude_location_;
 };
 
 }  // namespace fesa

include/fesa/loads/load.h

@@ -26,6 +26,8 @@ struct LoadContext {
   const Domain& domain;
   const DofManager& dof_manager;
   const SourceTargetResolver& target_resolver;
+  /// @brief Supplies the actual dynamic endpoint time for amplitude sampling.
+  double step_time{0.0};
 };
 
 /// @brief Produces local ordered load contributions without global mutation.

include/fesa/model/domain.h

@@ -112,6 +112,13 @@ class StepDefinition {
   /// @brief Returns the static maximum-increment provenance value.
   double MaximumIncrement() const noexcept;
 
+  /// @brief Reports the source STATIC DIRECT fixed-schedule selection.
+  bool IsDirectStatic() const noexcept;
+  /// @brief Returns the fixed Solid static increment count, or zero otherwise.
+  std::uint32_t IncrementCount() const noexcept;
+  /// @brief Returns the source static INC limit.
+  std::uint32_t MaximumIncrements() const noexcept;
+
   /// @brief Returns the source location of the step declaration.
   const SourceLocation& Location() const noexcept;
 
@@ -145,6 +152,9 @@ class StepDefinition {
   SourceLocation location_;
   std::optional<FrequencyStepDefinition> frequency_;
   std::optional<DynamicStepDefinition> dynamic_;
+  bool direct_static_{false};
+  std::uint32_t increment_count_{0U};
+  std::uint32_t maximum_increments_{100U};
 };
 
 /// @brief Owns the complete immutable semantic model definition.
@@ -176,6 +186,15 @@ class Domain {
   const DomainCollectionView<Mitc4ShellDefinition>& ShellElements()
       const noexcept;
 
+  /// @brief Returns C3D8 definitions in stable source order.
+  const DomainCollectionView<Hex8Definition>& SolidElements() const noexcept;
+  /// @brief Returns homogeneous Solid section assignments.
+  const DomainCollectionView<SolidSection>& SolidSections() const noexcept;
+  /// @brief Reports whether this model has exclusively Solid elements.
+  bool IsSolid() const noexcept;
+  /// @brief Returns immutable model-level amplitude curves in source order.
+  const std::vector<TabularAmplitudeDefinition>& Amplitudes() const noexcept;
+
   /// @brief Returns all materials in stable Domain index order.
   const DomainCollectionView<Material>& Materials() const noexcept;
 
@@ -262,6 +281,8 @@ class Domain {
   DomainCollectionView<ElementDefinition> elements_view_;
   DomainCollectionView<EulerBeam3DDefinition> beam_elements_view_;
   DomainCollectionView<Mitc4ShellDefinition> shell_elements_view_;
+  DomainCollectionView<Hex8Definition> solid_elements_view_;
+  DomainCollectionView<SolidSection> solid_sections_view_;
   DomainCollectionView<ElementProperty> properties_view_;
   DomainCollectionView<GeneralBeamSection> sections_view_;
   DomainCollectionView<ShellSection> shell_sections_view_;

include/fesa/model/model_types.h

@@ -1,6 +1,7 @@
 #ifndef FESA_MODEL_MODEL_TYPES_H_
 #define FESA_MODEL_MODEL_TYPES_H_
 
+#include <algorithm>
 #include <array>
 #include <cstdint>
 #include <filesystem>
@@ -14,11 +15,13 @@
 #include "fesa/core/source_identity.h"
 #include "fesa/elements/ds4_thermal.h"
 #include "fesa/elements/euler_beam_3d.h"
+#include "fesa/elements/hex8_definition.h"
 #include "fesa/elements/mitc4_shell.h"
 #include "fesa/materials/isotropic_linear_elastic_material.h"
 #include "fesa/materials/isotropic_thermal_material.h"
 #include "fesa/properties/general_beam_section.h"
 #include "fesa/properties/shell_section.h"
+#include "fesa/properties/solid_section.h"
 
 namespace fesa {
 
@@ -47,12 +50,37 @@ struct PrescribedDisplacementDefinition {
   SourceLocation location;
 };
 
+/// @brief Owns a validated TABULAR STEP TIME RELATIVE load curve.
+struct TabularAmplitudeDefinition {
+  std::string name_raw;
+  std::string name_canonical;
+  SourceLocation location;
+  std::vector<std::array<double, 2>> points;
+
+  /// @brief Evaluates exact knots, linear interiors, and endpoint holds.
+  /// @pre Time is finite; points are finite, nonempty, strictly increasing.
+  double Evaluate(double time) const {
+    if (time <= points.front()[0]) return points.front()[1];
+    if (time >= points.back()[0]) return points.back()[1];
+    const auto upper = std::lower_bound(
+        points.begin(), points.end(), time,
+        [](const auto& point, double t) { return point[0] < t; });
+    if ((*upper)[0] == time) return (*upper)[1];
+    const auto& lower = *(upper - 1);
+    const double weight = (time - lower[0]) / ((*upper)[0] - lower[0]);
+    return (1.0 - weight) * lower[1] + weight * (*upper)[1];
+  }
+};
+
 /// @brief Stores one concentrated nodal load component.
 struct NodalLoad {
   std::string target;
   int dof;
   double magnitude;
   SourceLocation location;
+  std::optional<EntityIndex> amplitude_index;
+  std::string amplitude_name_raw;
+  SourceLocation amplitude_location;
 };
 
 /// @brief Identifies the selected exterior shell surface side.
@@ -169,6 +197,9 @@ struct StaticStepDefinition {
   std::vector<PrescribedDisplacementDefinition> boundaries;
   std::vector<NodalLoad> loads;
   std::vector<SurfacePressureLoadDefinition> surface_pressure_loads;
+  bool direct{false};
+  std::uint32_t increment_count{0U};
+  std::uint32_t maximum_increments{100U};
   StaticProcedureKind procedure_kind;
   bool nlgeom;
   double initial_increment;
@@ -226,6 +257,7 @@ struct DynamicStepDefinition {
   double gamma{0.55};
   std::vector<PrescribedDisplacementDefinition> boundaries;
   std::vector<NodalLoad> loads;
+  bool nlgeom{true};
 };
 
 /// @brief Stores homogeneous isotropic thermal material source data.
@@ -374,10 +406,13 @@ struct ModelDefinition {
   std::vector<Node> nodes;
   std::vector<EulerBeam3DDefinition> elements;
   std::vector<Mitc4ShellDefinition> shell_elements;
+  std::vector<Hex8Definition> solid_elements;
   std::vector<LinearElasticMaterial> materials;
   std::vector<ThermalMaterialDefinition> thermal_materials;
   std::vector<GeneralBeamSection> sections;
   std::vector<ShellSection> shell_sections;
+  std::vector<SolidSection> solid_sections;
+  std::vector<TabularAmplitudeDefinition> amplitudes;
   std::vector<ThermalShellSectionDefinition> thermal_sections;
   std::vector<Ds4ThermalElementDefinition> thermal_elements;
   std::vector<ShellNodeInitialFrame> shell_node_initial_frames;

include/fesa/properties/element_property.h

@@ -6,7 +6,11 @@
 namespace fesa {
 
 /// @brief Identifies the supported concrete element-property semantics.
-enum class ElementPropertyKind { kGeneralBeamSection, kShellSection };
+enum class ElementPropertyKind {
+  kGeneralBeamSection,
+  kShellSection,
+  kSolidSection
+};
 
 /// @brief Provides stable identity for a Domain-owned element property.
 class ElementProperty {

include/fesa/properties/solid_section.h

@@ -0,0 +1,39 @@
+#ifndef FESA_PROPERTIES_SOLID_SECTION_H_
+#define FESA_PROPERTIES_SOLID_SECTION_H_
+
+#include <string>
+#include <utility>
+
+#include "fesa/properties/element_property.h"
+
+namespace fesa {
+/// @brief Owns a homogeneous Solid material assignment without thickness.
+class SolidSection final : public ElementProperty {
+ public:
+  /// @brief Constructs a parser-validated ELSET and material assignment.
+  SolidSection(SourceEntityId source, std::string name,
+               EntityIndex material_index, SourceLocation location)
+      : source_id_{std::move(source)},
+        name_{std::move(name)},
+        material_index_{material_index},
+        location_{std::move(location)} {}
+  ElementPropertyKind Kind() const noexcept override {
+    return ElementPropertyKind::kSolidSection;
+  }
+  const SourceEntityId& SourceId() const noexcept override {
+    return source_id_;
+  }
+  const SourceLocation& Location() const noexcept override { return location_; }
+  /// @brief Returns the source ELSET spelling.
+  const std::string& Name() const noexcept { return name_; }
+  /// @brief Returns the stable Domain material index.
+  EntityIndex MaterialIndex() const noexcept { return material_index_; }
+
+ private:
+  SourceEntityId source_id_;
+  std::string name_;
+  EntityIndex material_index_;
+  SourceLocation location_;
+};
+}  // namespace fesa
+#endif  // FESA_PROPERTIES_SOLID_SECTION_H_

src/fesa/assembly/load_assembler.cpp

@@ -98,7 +98,8 @@ Status ValidateShellMoments(const Domain& domain, const Vector& full_load) {
 }  // namespace
 
 Result<Vector> LoadAssembler::AssembleFullNodalLoad(const AnalysisModel& model,
-                                                    const DofManager& dofs) {
+                                                    const DofManager& dofs,
+                                                    double step_time) {
   const auto& active_loads = model.ActiveLoads();
   const auto& owned_loads = model.Step().Loads();
   if (active_loads.size() != owned_loads.size()) {
@@ -122,21 +123,31 @@ Result<Vector> LoadAssembler::AssembleFullNodalLoad(const AnalysisModel& model,
     }
     loads.push_back(owned_loads[load_index]);
   }
-  return AssembleFullNodalLoad(model, dofs, loads);
+  return AssembleFullNodalLoad(model, dofs, loads, step_time);
 }
 
 Result<Vector> LoadAssembler::AssembleFullNodalLoad(const AnalysisModel& model,
                                                     const DofManager& dofs,
-                                                    const LoadView& loads) {
+                                                    const LoadView& loads,
+                                                    double step_time) {
   const Domain& domain = model.GetDomain();
+  const std::size_t components = dofs.ComponentsPerNode();
+  if (dofs.Profile() == DofProfile::kThermal ||
+      (domain.IsSolid() != (dofs.Profile() == DofProfile::kSolidStructural)) ||
+      !std::isfinite(step_time) || step_time < 0.0) {
+    return Result<Vector>::Failure(LoadFailure(
+        "invalid-load-context", {domain.SourcePath(), 0U}, "LOAD_ASSEMBLER", "",
+        "Nodal loads require the matching structural profile and finite "
+        "nonnegative endpoint time."));
+  }
   if (domain.Nodes().size() >
-      (std::numeric_limits<std::size_t>::max)() / kDofsPerNode) {
+      (std::numeric_limits<std::size_t>::max)() / components) {
     return Result<Vector>::Failure(LoadFailure(
         "invalid-load-dimensions", {domain.SourcePath(), 0U}, "LOAD_ASSEMBLER",
         domain.SourceContentIdentity(),
         "The semantic node count cannot be represented in full-DOF order."));
   }
-  const std::size_t expected_full_count = domain.Nodes().size() * kDofsPerNode;
+  const std::size_t expected_full_count = domain.Nodes().size() * components;
   if (dofs.FullDofCount() != expected_full_count) {
     return Result<Vector>::Failure(LoadFailure(
         "invalid-load-dimensions", {domain.SourcePath(), 0U}, "LOAD_ASSEMBLER",
@@ -148,11 +159,11 @@ Result<Vector> LoadAssembler::AssembleFullNodalLoad(const AnalysisModel& model,
     return Result<Vector>::Failure(dof_status);
   }
   for (std::size_t node = 0U; node < domain.Nodes().size(); ++node) {
-    for (std::size_t component = 0U; component < kDofsPerNode; ++component) {
+    for (std::size_t component = 0U; component < components; ++component) {
       try {
         if (dofs.FullDof(static_cast<EntityIndex>(node),
                          static_cast<DofComponent>(component)) !=
-            node * kDofsPerNode + component) {
+            node * components + component) {
           return Result<Vector>::Failure(LoadFailure(
               "invalid-load-order", domain.Nodes()[node].location,
               "LOAD_ASSEMBLER",
@@ -170,7 +181,7 @@ Result<Vector> LoadAssembler::AssembleFullNodalLoad(const AnalysisModel& model,
 
   const SourceTargetIndex target_index = SourceTargetIndex::FromDomain(domain);
   const SourceTargetResolver target_resolver{target_index};
-  const LoadContext context{domain, dofs, target_resolver};
+  const LoadContext context{domain, dofs, target_resolver, step_time};
 
   std::vector<std::vector<LoadContribution>> contributions_by_load;
   contributions_by_load.reserve(loads.size());

src/fesa/fem/dof_manager.cpp

@@ -116,8 +116,12 @@ Result<DofManager> DofManager::Create(const AnalysisModel& model) {
                      "An active element index is outside the Domain."));
     }
     const auto& definition = domain.Elements()[element_index];
-    layouts.push_back({definition.SourceId(), definition.NodeIndices(),
-                       FullNodeComponents()});
+    layouts.push_back(
+        {definition.SourceId(), definition.NodeIndices(),
+         domain.IsSolid()
+             ? std::vector<DofComponent>{DofComponent::kUx, DofComponent::kUy,
+                                         DofComponent::kUz}
+             : FullNodeComponents()});
   }
 
   DofManager dofs;
@@ -305,6 +309,19 @@ Status DofManager::BuildLayouts(const AnalysisModel& analysis_model,
        ++source_order) {
     const EntityIndex definition_index =
         analysis_model.ActiveElements()[source_order];
+    if (domain.IsSolid()) {
+      const std::vector<DofComponent> translations{
+          DofComponent::kUx, DofComponent::kUy, DofComponent::kUz};
+      if (layouts[source_order].components_per_node != translations ||
+          definition_index >= domain.Elements().Size() ||
+          layouts[source_order].node_indices !=
+              domain.Elements()[definition_index].NodeIndices()) {
+        return DofFailure(
+            "invalid-solid-element-layout", {domain.SourcePath(), 0U},
+            std::to_string(source_order),
+            "Solid layouts require source-ordered eight nodes and UX/UY/UZ.");
+      }
+    }
     if (definition_index >= domain.Elements().Size() ||
         !SameSourceIdentity(layouts[source_order].source_id,
                             domain.Elements()[definition_index].SourceId())) {
@@ -318,10 +335,13 @@ Status DofManager::BuildLayouts(const AnalysisModel& analysis_model,
 
   const SourceTargetIndex target_index = SourceTargetIndex::FromDomain(domain);
   const SourceTargetResolver target_resolver{target_index};
-  const std::size_t full_count = domain.Nodes().size() * kDofsPerNode;
+  const std::size_t component_count = domain.IsSolid() ? 3U : kDofsPerNode;
+  const std::size_t full_count = domain.Nodes().size() * component_count;
 
   DofManager full_dof_map;
   full_dof_map.full_dof_count_ = full_count;
+  full_dof_map.profile_ =
+      domain.IsSolid() ? DofProfile::kSolidStructural : DofProfile::kStructural;
   const BoundaryConditionContext context{domain, full_dof_map, target_resolver};
   std::vector<std::vector<ConstraintDefinition>> definitions_by_boundary;
   definitions_by_boundary.reserve(boundaries.size());
@@ -417,6 +437,7 @@ Status DofManager::BuildLayouts(const AnalysisModel& analysis_model,
                        std::move(constrained_dofs),
                        std::move(prescribed_values),
                        {}};
+  candidate.profile_ = full_dof_map.profile_;
   candidate.element_scatters_.reserve(layouts.size());
   for (const auto& layout : layouts) {
     auto scatter = candidate.ElementScatter(layout);
@@ -441,6 +462,10 @@ std::size_t DofManager::FullDofCount() const noexcept {
 }
 
 DofProfile DofManager::Profile() const noexcept { return profile_; }
+std::size_t DofManager::ComponentsPerNode() const noexcept {
+  if (profile_ == DofProfile::kThermal) return kThermalDofsPerNode;
+  return profile_ == DofProfile::kSolidStructural ? 3U : kDofsPerNode;
+}
 
 std::size_t DofManager::FreeDofCount() const noexcept {
   return free_dofs_.size();
@@ -452,15 +477,16 @@ std::size_t DofManager::ConstrainedDofCount() const noexcept {
 
 std::size_t DofManager::FullDof(const EntityIndex node,
                                 const DofComponent component) const {
-  if (profile_ != DofProfile::kStructural) {
-    throw std::logic_error{"Structural components are invalid for thermal DOFs."};
+  if (profile_ == DofProfile::kThermal) {
+    throw std::logic_error{
+        "Structural components are invalid for thermal DOFs."};
   }
   const std::size_t component_index = static_cast<std::size_t>(component);
-  if (node >= full_dof_count_ / kDofsPerNode ||
-      component_index >= kDofsPerNode) {
+  if (node >= full_dof_count_ / ComponentsPerNode() ||
+      component_index >= ComponentsPerNode()) {
     throw std::out_of_range{"Node or DOF component is out of range."};
   }
-  return static_cast<std::size_t>(node) * kDofsPerNode + component_index;
+  return static_cast<std::size_t>(node) * ComponentsPerNode() + component_index;
 }
 
 std::size_t DofManager::FullThermalDof(
@@ -481,7 +507,7 @@ std::optional<std::size_t> DofManager::FreeEquation(
 
 Result<std::vector<std::size_t>> DofManager::ElementScatter(
     const ElementDofLayout& layout) const {
-  if (profile_ != DofProfile::kStructural) {
+  if (profile_ == DofProfile::kThermal) {
     return Result<std::vector<std::size_t>>::Failure(DofFailure(
         "invalid-dof-profile", {}, layout.source_id.source_label_text,
         "Structural layouts are invalid for a thermal mapping."));
@@ -501,8 +527,8 @@ Result<std::vector<std::size_t>> DofManager::ElementScatter(
   for (const EntityIndex node : layout.node_indices) {
     for (const DofComponent component : layout.components_per_node) {
       const std::size_t component_index = static_cast<std::size_t>(component);
-      if (node >= full_dof_count_ / kDofsPerNode ||
-          component_index >= kDofsPerNode) {
+      if (node >= full_dof_count_ / ComponentsPerNode() ||
+          component_index >= ComponentsPerNode()) {
         return Result<std::vector<std::size_t>>::Failure(DofFailure(
             "invalid-element-dof-layout", {},
             layout.source_id.source_label_text,
@@ -510,7 +536,8 @@ Result<std::vector<std::size_t>> DofManager::ElementScatter(
             "DOF range."));
       }
       const std::size_t full_dof =
-          static_cast<std::size_t>(node) * kDofsPerNode + component_index;
+          static_cast<std::size_t>(node) * ComponentsPerNode() +
+          component_index;
       if (std::find(scatter.begin(), scatter.end(), full_dof) !=
           scatter.end()) {
         return Result<std::vector<std::size_t>>::Failure(DofFailure(

src/fesa/io/abaqus/domain_mapping_context.cpp

@@ -50,7 +50,7 @@ struct RawNode {
 };
 
 struct RawElement {
-  enum class Type { kB33, kS4, kS4r, kDs4 };
+  enum class Type { kB33, kS4, kS4r, kDs4, kC3d8 };
 
   std::int64_t label;
   std::string label_text;
@@ -59,7 +59,7 @@ struct RawElement {
   SourceLocation location;
 };
 
-enum class ElementFamily { kBeam, kShell, kThermalShell };
+enum class ElementFamily { kBeam, kShell, kThermalShell, kSolid };
 
 struct RawSet {
   std::string name;
@@ -83,6 +83,12 @@ struct RawShellSection {
   SourceLocation location;
 };
 
+struct RawSolidSection {
+  std::string element_set_name;
+  std::string material_name;
+  SourceLocation location;
+};
+
 struct RawPart {
   std::string name;
   SourceLocation location;
@@ -92,6 +98,7 @@ struct RawPart {
   std::vector<RawSet> element_sets;
   std::vector<RawSection> sections;
   std::vector<RawShellSection> shell_sections;
+  std::vector<RawSolidSection> solid_sections;
 };
 
 struct RawInstance {
@@ -170,6 +177,8 @@ struct RawStep {
   std::string name_raw;
   std::string name_canonical;
   bool has_static{false};
+  bool static_direct{false};
+  std::uint32_t static_increment_count{0U};
   std::optional<DynamicStepDefinition> dynamic;
   bool perturbation_explicit{false};
   bool nlgeom_explicit{false};
@@ -746,6 +755,10 @@ class DomainMappingContext::Impl {
       ParseAssemblyStart(block);
       return;
     }
+    if (block.canonical_name == "AMPLITUDE") {
+      ParseAmplitude(block);
+      return;
+    }
     if (block.canonical_name == "MATERIAL") {
       ParseMaterial(block);
       return;
@@ -841,7 +854,8 @@ class DomainMappingContext::Impl {
           model_element_family_ == ElementFamily::kShell ||
           model_element_family_ == ElementFamily::kThermalShell;
       if (part.nodes.empty() || part.elements.empty() ||
-          (!shell_part && part.sections.empty())) {
+          (!shell_part && model_element_family_ != ElementFamily::kSolid &&
+           part.sections.empty())) {
         InvalidKeywordLocation(block,
                                "A part closes only after node, element, "
                                "and matching section blocks.");
@@ -917,7 +931,8 @@ class DomainMappingContext::Impl {
         return;
       }
       if (model_element_family_ == ElementFamily::kShell ||
-          model_element_family_ == ElementFamily::kThermalShell) {
+          model_element_family_ == ElementFamily::kThermalShell ||
+          model_element_family_ == ElementFamily::kSolid) {
         InputFailure(
             "unsupported-mixed-element-model", block.location,
             block.canonical_name, "",
@@ -934,7 +949,8 @@ class DomainMappingContext::Impl {
             block, "SHELL SECTION follows the part mesh and optional sets.");
         return;
       }
-      if (model_element_family_ == ElementFamily::kBeam) {
+      if (model_element_family_ == ElementFamily::kBeam ||
+          model_element_family_ == ElementFamily::kSolid) {
         InputFailure(
             "unsupported-mixed-element-model", block.location,
             block.canonical_name, "",
@@ -943,6 +959,17 @@ class DomainMappingContext::Impl {
       }
       ParseShellSection(block, part);
       part_sections_seen_ = !failure_;
+    } else if (block.canonical_name == "SOLID SECTION") {
+      beam_section_context_active_ = false;
+      if (!part_elements_seen_ ||
+          model_element_family_ != ElementFamily::kSolid) {
+        InputFailure("invalid-solid-section", block.location,
+                     block.canonical_name, "",
+                     "SOLID SECTION requires an exclusive C3D8 mesh.");
+        return;
+      }
+      ParseSolidSection(block, part);
+      part_sections_seen_ = !failure_;
     } else if (block.canonical_name == "SECTION POINTS") {
       ParseSectionPoints(block, part);
     } else if (block.canonical_name == "TRANSVERSE SHEAR STIFFNESS") {
@@ -1011,8 +1038,10 @@ class DomainMappingContext::Impl {
     const bool thermal_block =
         type_parameter && type_parameter->value &&
         AsciiCaseInsensitiveEquals(*type_parameter->value, "DS4");
-    if (!ValidateParameters(block,
-                            thermal_block
+    if (!ValidateParameters(
+            block, (thermal_block || (type_parameter && type_parameter->value &&
+                                      AsciiCaseInsensitiveEquals(
+                                          *type_parameter->value, "C3D8")))
                        ? std::vector<std::string_view>{"TYPE", "ELSET"}
                        : std::vector<std::string_view>{"TYPE"})) {
       return;
@@ -1036,6 +1065,10 @@ class DomainMappingContext::Impl {
       element_type = RawElement::Type::kS4r;
       element_family = ElementFamily::kShell;
       expected_field_count = 5U;
+    } else if (AsciiCaseInsensitiveEquals(*type, "C3D8")) {
+      element_type = RawElement::Type::kC3d8;
+      element_family = ElementFamily::kSolid;
+      expected_field_count = 9U;
     } else if (AsciiCaseInsensitiveEquals(*type, "DS4")) {
       element_type = RawElement::Type::kDs4;
       element_family = ElementFamily::kThermalShell;
@@ -1043,15 +1076,16 @@ class DomainMappingContext::Impl {
     } else {
       InputFailure("unsupported-element-formulation", block.location,
                    block.canonical_name, *type,
-                   "Only TYPE=B33, TYPE=S4, TYPE=S4R, and TYPE=DS4 belong to "
+                   "Only B33, S4, S4R, DS4, and C3D8 belong to "
                    "the approved "
                    "element subsets.");
       return;
     }
     if (model_element_family_ && *model_element_family_ != element_family) {
-      InputFailure("unsupported-mixed-element-model", block.location,
+      InputFailure(
+          "unsupported-mixed-element-model", block.location,
           block.canonical_name, *type,
-                   "Beam and shell elements cannot be mixed in one model.");
+          "Beam, Shell, thermal, and Solid families cannot mix in one model.");
       return;
     }
     model_element_family_ = element_family;
@@ -1067,9 +1101,11 @@ class DomainMappingContext::Impl {
       inline_set = RawSet{*name, {}, block.location};
     }
     if (block.data.empty()) {
-      InputFailure(element_family == ElementFamily::kShell
+      InputFailure(element_family == ElementFamily::kSolid
+                       ? "invalid-solid-connectivity"
+                       : (element_family == ElementFamily::kShell
                               ? "invalid-shell-connectivity"
-                       : "invalid-data-arity",
+                              : "invalid-data-arity"),
                    block.location, block.canonical_name, "",
                    "ELEMENT requires at least one row with the approved "
                    "connectivity arity.");
@@ -1078,9 +1114,11 @@ class DomainMappingContext::Impl {
     for (const auto& row : block.data) {
       if (row.fields.size() != expected_field_count) {
         InputFailure(
-            element_family == ElementFamily::kShell
+            element_family == ElementFamily::kSolid
+                ? "invalid-solid-connectivity"
+                : (element_family == ElementFamily::kShell
                        ? "invalid-shell-connectivity"
-                : "invalid-data-arity",
+                       : "invalid-data-arity"),
             row.location, block.canonical_name, "",
             element_family == ElementFamily::kShell
                 ? "S4 and S4R rows require a label and exactly four nodes."
@@ -1108,10 +1146,12 @@ class DomainMappingContext::Impl {
         const std::set<std::int64_t> distinct_nodes{element.node_labels.begin(),
                                                     element.node_labels.end()};
         if (distinct_nodes.size() != element.node_labels.size()) {
-          InputFailure(
-              "invalid-shell-connectivity", row.location, block.canonical_name,
-              element.label_text,
-              "Shell connectivity requires four distinct source nodes.");
+          InputFailure(element_family == ElementFamily::kSolid
+                           ? "invalid-solid-connectivity"
+                           : "invalid-shell-connectivity",
+                       row.location, block.canonical_name, element.label_text,
+                       "Connectivity requires the specified number of distinct "
+                       "source nodes.");
           return;
         }
       }
@@ -1132,6 +1172,101 @@ class DomainMappingContext::Impl {
     if (inline_set) part.element_sets.push_back(std::move(*inline_set));
   }
 
+  /// @brief Parses material-only Solid assignment without thickness defaults.
+  void ParseSolidSection(const KeywordBlock& block, RawPart& part) {
+    if (!ValidateParameters(block, {"ELSET", "MATERIAL"})) return;
+    const auto* elset = RequiredParameterValue(block, "ELSET");
+    const auto* material = RequiredParameterValue(block, "MATERIAL");
+    if (!elset || !material) return;
+    if (block.data.size() > 1U ||
+        (!block.data.empty() &&
+         std::any_of(block.data[0].fields.begin(), block.data[0].fields.end(),
+                     [](const auto& field) { return !field.empty(); }))) {
+      InputFailure("invalid-solid-section", block.location,
+                   block.canonical_name, *elset,
+                   "SOLID SECTION permits omitted or blank data only.");
+      return;
+    }
+    part.solid_sections.push_back({*elset, *material, block.location});
+  }
+
+  /// @brief Validates and owns one model-level supported load amplitude.
+  void ParseAmplitude(const KeywordBlock& block) {
+    const bool dynamic_source = std::any_of(
+        input_.blocks.begin(), input_.blocks.end(), [](const auto& candidate) {
+          return candidate.canonical_name == "DYNAMIC";
+        });
+    if (model_element_family_ != ElementFamily::kSolid || !dynamic_source) {
+      InputFailure("unsupported-load-amplitude", block.location,
+                   block.canonical_name, "",
+                   "Amplitude is supported only in Solid dynamic models.");
+      return;
+    }
+    if (!ValidateParameters(block, {"NAME", "DEFINITION", "TIME", "VALUE"}))
+      return;
+    const auto* name = RequiredParameterValue(block, "NAME");
+    if (!name) return;
+    for (const auto& option :
+         std::array<std::pair<const char*, const char*>, 3>{
+             {{"DEFINITION", "TABULAR"},
+              {"TIME", "STEP TIME"},
+              {"VALUE", "RELATIVE"}}}) {
+      const auto* parameter = Parameter(block, option.first);
+      if (parameter &&
+          (!parameter->value ||
+           !AsciiCaseInsensitiveEquals(*parameter->value, option.second))) {
+        InputFailure("unsupported-amplitude-option", block.location,
+                     block.canonical_name, option.first,
+                     "Only TABULAR STEP TIME RELATIVE amplitude is supported.");
+        return;
+      }
+    }
+    const std::string canonical = CanonicalizeAscii(*name);
+    if (std::any_of(definition_.amplitudes.begin(),
+                    definition_.amplitudes.end(), [&canonical](const auto& a) {
+                      return a.name_canonical == canonical;
+                    })) {
+      InputFailure("duplicate-amplitude", block.location, block.canonical_name,
+                   *name,
+                   "Amplitude names must be unique ignoring ASCII case.");
+      return;
+    }
+    TabularAmplitudeDefinition amplitude{*name, canonical, block.location, {}};
+    for (const auto& row : block.data) {
+      if (row.fields.empty() || row.fields.size() % 2U != 0U) {
+        InputFailure("invalid-amplitude-data", row.location,
+                     block.canonical_name, *name,
+                     "Amplitude rows require complete time/value pairs.");
+        return;
+      }
+      for (std::size_t field = 0U; field < row.fields.size(); field += 2U) {
+        double time = 0.0;
+        double value = 0.0;
+        if (!ParseDouble(row.fields[field], time, row.location,
+                         block.canonical_name) ||
+            !ParseDouble(row.fields[field + 1U], value, row.location,
+                         block.canonical_name))
+          return;
+        if (time < 0.0 || (!amplitude.points.empty() &&
+                           !(time > amplitude.points.back()[0]))) {
+          InputFailure(
+              "invalid-amplitude-data", row.location, block.canonical_name,
+              *name,
+              "Amplitude times must be nonnegative and strictly increasing.");
+          return;
+        }
+        amplitude.points.push_back({time, value});
+      }
+    }
+    if (amplitude.points.empty()) {
+      InputFailure("invalid-amplitude-data", block.location,
+                   block.canonical_name, *name,
+                   "Amplitude requires at least one finite time/value pair.");
+      return;
+    }
+    definition_.amplitudes.push_back(std::move(amplitude));
+  }
+
   void ParseShellSection(const KeywordBlock& block, RawPart& part) {
     for (const auto& candidate : block.parameters) {
       if (candidate.name != "ELSET" && candidate.name != "MATERIAL") {
@@ -1735,13 +1870,17 @@ class DomainMappingContext::Impl {
     }
     if (!ParseModelDouble(block.data[0].fields[0], material.youngs_modulus,
                           block.data[0].location, block.canonical_name,
-                          model_element_family_ == ElementFamily::kShell
+                          model_element_family_ == ElementFamily::kSolid
+                              ? "invalid-solid-material"
+                          : model_element_family_ == ElementFamily::kShell
                               ? "invalid-shell-material"
                               : "invalid-beam-property",
                           "Elastic material values must be finite.") ||
         !ParseModelDouble(block.data[0].fields[1], material.poisson_ratio,
                           block.data[0].location, block.canonical_name,
-                          model_element_family_ == ElementFamily::kShell
+                          model_element_family_ == ElementFamily::kSolid
+                              ? "invalid-solid-material"
+                          : model_element_family_ == ElementFamily::kShell
                               ? "invalid-shell-material"
                               : "invalid-beam-property",
                           "Elastic material values must be finite.")) {
@@ -2006,6 +2145,8 @@ class DomainMappingContext::Impl {
       }
       double value = 0.0;
       if (row.fields.size() == 4U &&
+          !(model_element_family_ == ElementFamily::kSolid &&
+            row.fields[3].empty()) &&
           !ParseDouble(row.fields[3], value, row.location,
                        block.canonical_name)) {
         return;
@@ -2016,19 +2157,46 @@ class DomainMappingContext::Impl {
   }
 
   void ParseCload(const KeywordBlock& block, std::vector<NodalLoad>& loads) {
-    if (step_.dynamic && !block.parameters.empty()) {
+    if (step_.dynamic && model_element_family_ != ElementFamily::kSolid &&
+        !block.parameters.empty()) {
       InputFailure("unsupported-dynamic-load", block.location,
                    block.canonical_name, "",
                    "Dynamic CLOAD does not support keyword parameters.");
       return;
     }
-    if (!ValidateParameters(block, {}) || block.data.empty()) {
+    const bool solid_dynamic =
+        step_.dynamic && model_element_family_ == ElementFamily::kSolid;
+    if (!ValidateParameters(
+            block, solid_dynamic ? std::vector<std::string_view>{"AMPLITUDE"}
+                                 : std::vector<std::string_view>{}) ||
+        block.data.empty()) {
       if (!failure_) {
         InputFailure("invalid-data-arity", block.location, block.canonical_name,
                      "", "CLOAD requires one or more rows.");
       }
       return;
     }
+    std::optional<EntityIndex> amplitude_index;
+    std::string amplitude_name;
+    if (Parameter(block, "AMPLITUDE")) {
+      const auto* name = RequiredParameterValue(block, "AMPLITUDE");
+      if (!name) return;
+      amplitude_name = *name;
+      for (std::size_t index = 0U; index < definition_.amplitudes.size();
+           ++index) {
+        if (AsciiCaseInsensitiveEquals(definition_.amplitudes[index].name_raw,
+                                       *name)) {
+          amplitude_index = static_cast<EntityIndex>(index);
+          break;
+        }
+      }
+      if (!amplitude_index) {
+        InputFailure("unresolved-amplitude", block.location,
+                     block.canonical_name, *name,
+                     "CLOAD amplitude must resolve to a model-level curve.");
+        return;
+      }
+    }
     for (const auto& row : block.data) {
       if (row.fields.size() != 3U || row.fields[0].empty()) {
         InputFailure("invalid-data-arity", row.location, block.canonical_name,
@@ -2048,15 +2216,17 @@ class DomainMappingContext::Impl {
                      row.fields[0], "CLOAD DOF must be in 1..6.");
         return;
       }
-      if (step_.dynamic && dof > 3) {
+      if ((step_.dynamic || model_element_family_ == ElementFamily::kSolid) &&
+          dof > 3) {
         InputFailure("unsupported-dynamic-load", row.location,
                      block.canonical_name, row.fields[1],
                      "Dynamic CLOAD supports global translational DOF 1 "
                      "through 3 only.");
         return;
       }
-      loads.push_back(
-          {row.fields[0], static_cast<int>(dof), magnitude, row.location});
+      loads.push_back({row.fields[0], static_cast<int>(dof), magnitude,
+                       row.location, amplitude_index, amplitude_name,
+                       block.location});
     }
   }
 
@@ -2148,10 +2318,11 @@ class DomainMappingContext::Impl {
         return;
       }
       if (AsciiCaseInsensitiveEquals(*nlgeom_parameter->value, "YES")) {
-        if (model_element_family_ != ElementFamily::kShell) {
+        if (model_element_family_ != ElementFamily::kShell &&
+            model_element_family_ != ElementFamily::kSolid) {
           InputFailure("unsupported-analysis-procedure", block.location,
                        block.canonical_name, *nlgeom_parameter->value,
-                       "NLGEOM=YES requires an S4 or S4R shell model.");
+                       "NLGEOM=YES requires a supported Shell or Solid model.");
           return;
         }
         procedure_kind = StaticProcedureKind::kNonlinearFullNewton;
@@ -2216,6 +2387,16 @@ class DomainMappingContext::Impl {
   }
 
   void ParseStepBlock(const KeywordBlock& block) {
+    if (model_element_family_ == ElementFamily::kSolid &&
+        (block.canonical_name == "STATIC" ||
+         block.canonical_name == "FREQUENCY" ||
+         block.canonical_name == "DYNAMIC") &&
+        (step_.has_static || step_.frequency || step_.dynamic)) {
+      InputFailure("unsupported-analysis-procedure", block.location,
+                   block.canonical_name, step_.name_raw,
+                   "Solid steps accept exactly one procedure.");
+      return;
+    }
     if (model_element_family_ == ElementFamily::kThermalShell &&
         (block.canonical_name == "STATIC" ||
          block.canonical_name == "FREQUENCY" ||
@@ -2353,17 +2534,17 @@ class DomainMappingContext::Impl {
         return;
       }
       step_no_op_seen_ = true;
-      if (step_.frequency || step_.has_heat_transfer) {
+      if (step_.frequency || step_.has_heat_transfer ||
+          model_element_family_ == ElementFamily::kSolid) {
         const auto* write = Parameter(block, "WRITE");
         const auto* frequency = Parameter(block, "FREQUENCY");
         if (!ValidateParameters(block, {"WRITE", "FREQUENCY"}) ||
             write == nullptr || write->value || frequency == nullptr ||
             !frequency->value || *frequency->value != "0") {
           if (!failure_) {
-            InputFailure("unsupported-keyword", block.location,
-                         block.canonical_name, "",
-                         "Dynamic and frequency RESTART accept only WRITE, "
-                         "FREQUENCY=0.");
+            InputFailure(
+                "unsupported-keyword", block.location, block.canonical_name, "",
+                "Supported RESTART no-op requires WRITE, FREQUENCY=0.");
           }
           return;
         }
@@ -2553,18 +2734,26 @@ class DomainMappingContext::Impl {
   }
 
   void ParseDynamic(const KeywordBlock& block) {
-    if (step_.perturbation_explicit || !step_.nlgeom ||
-        model_element_family_ != ElementFamily::kShell ||
+    if (step_.perturbation_explicit ||
+        (model_element_family_ != ElementFamily::kSolid &&
+         (!step_.nlgeom || model_element_family_ != ElementFamily::kShell)) ||
         !ValidateParameters(block, {"DIRECT"},
                             "unsupported-dynamic-parameter")) {
       if (!failure_) {
-        InputFailure(
-            "unsupported-analysis-procedure", block.location,
+        InputFailure("unsupported-analysis-procedure", block.location,
                      block.canonical_name, "",
-            "DYNAMIC requires the approved nonlinear shell configuration.");
+                     "DYNAMIC requires nonlinear Shell or linear/nonlinear "
+                     "Solid geometry.");
       }
       return;
     }
+    if (model_element_family_ == ElementFamily::kSolid &&
+        block.data.size() == 1U && block.data[0].fields.size() > 3U) {
+      InputFailure("invalid-dynamic-data", block.data[0].location,
+                   block.canonical_name, "",
+                   "Solid DYNAMIC requires h,T with at most one blank field.");
+      return;
+    }
     const auto* direct = Parameter(block, "DIRECT");
     if (direct == nullptr || direct->value || block.data.size() != 1U ||
         block.data[0].fields.size() < 2U ||
@@ -2622,6 +2811,7 @@ class DomainMappingContext::Impl {
                    "DYNAMIC,DIRECT increment count cannot exceed STEP INC.");
       return;
     }
+    dynamic.nlgeom = step_.nlgeom;
     step_.dynamic = std::move(dynamic);
   }
 
@@ -2716,6 +2906,51 @@ class DomainMappingContext::Impl {
   }
 
   void ParseStatic(const KeywordBlock& block) {
+    if (model_element_family_ == ElementFamily::kSolid &&
+        Parameter(block, "DIRECT")) {
+      if (step_.perturbation_explicit || step_.has_static || step_.frequency ||
+          step_.dynamic) {
+        InputFailure("unsupported-analysis-procedure", block.location,
+                     block.canonical_name, step_.name_raw,
+                     "STATIC DIRECT requires one non-perturbation procedure.");
+        return;
+      }
+      if (!ValidateParameters(block, {"DIRECT"})) return;
+      const auto* direct = Parameter(block, "DIRECT");
+      if (direct->value || block.data.size() != 1U ||
+          (block.data[0].fields.size() < 2U ||
+           block.data[0].fields.size() > 3U ||
+           std::any_of(block.data[0].fields.begin() + 2,
+                       block.data[0].fields.end(),
+                       [](const auto& field) { return !field.empty(); }))) {
+        InputFailure("invalid-static-data", block.location,
+                     block.canonical_name, "DIRECT",
+                     "STATIC DIRECT requires exactly h,T.");
+        return;
+      }
+      double h = 0.0;
+      double period = 0.0;
+      if (!ParseDouble(block.data[0].fields[0], h, block.data[0].location,
+                       "STATIC") ||
+          !ParseDouble(block.data[0].fields[1], period, block.data[0].location,
+                       "STATIC"))
+        return;
+      const double count = std::round(period / h);
+      if (!(h > 0.0) || !(period > 0.0) || !std::isfinite(count) ||
+          count < 1.0 ||
+          count > static_cast<double>(step_.maximum_increments) ||
+          h * count != period) {
+        InputFailure("invalid-static-schedule", block.data[0].location,
+                     block.canonical_name, "DIRECT",
+                     "STATIC DIRECT requires positive exact N*h=T and N<=INC.");
+        return;
+      }
+      step_.static_values = {h, period, h, h};
+      step_.static_direct = true;
+      step_.static_increment_count = static_cast<std::uint32_t>(count);
+      step_.has_static = true;
+      return;
+    }
     if (step_.perturbation_explicit || step_.frequency) {
       InputFailure("unsupported-analysis-procedure", block.location,
                    block.canonical_name, "PERTURBATION",
@@ -2811,6 +3046,17 @@ class DomainMappingContext::Impl {
           "OUTPUT must select exactly FIELD or HISTORY.");
       return;
     }
+    if (model_element_family_ == ElementFamily::kSolid &&
+        ((variable &&
+          (!variable->value ||
+           !AsciiCaseInsensitiveEquals(*variable->value, "PRESELECT"))) ||
+         !RequireNoData(block))) {
+      if (!failure_)
+        InputFailure("unsupported-keyword", block.location,
+                     block.canonical_name, "VARIABLE",
+                     "Solid OUTPUT accepts only PRESELECT requests.");
+      return;
+    }
     if (step_.nlgeom &&
         (variable == nullptr || !variable->value ||
          !AsciiCaseInsensitiveEquals(*variable->value, "PRESELECT"))) {
@@ -2865,6 +3111,50 @@ class DomainMappingContext::Impl {
           "Output variable keywords require an active OUTPUT request.");
       return;
     }
+    if (model_element_family_ == ElementFamily::kSolid && step_.dynamic) {
+      InputFailure(
+          "unsupported-keyword", block.location, block.canonical_name, "",
+          "Solid dynamic output children are outside the approved subset.");
+      return;
+    }
+    if (model_element_family_ == ElementFamily::kSolid && step_.has_static) {
+      const auto* variable = Parameter(block, "VARIABLE");
+      const auto* directions = Parameter(block, "DIRECTIONS");
+      const bool node = block.canonical_name == "NODE OUTPUT";
+      const bool element = block.canonical_name == "ELEMENT OUTPUT";
+      const bool contact = block.canonical_name == "CONTACT OUTPUT";
+      if (!active_output_is_field_ || (!node && !element && !contact) ||
+          !ValidateParameters(
+              block,
+              element ? std::vector<std::string_view>{"VARIABLE", "DIRECTIONS"}
+                      : std::vector<std::string_view>{"VARIABLE"}) ||
+          (directions &&
+           (!directions->value ||
+            !AsciiCaseInsensitiveEquals(*directions->value, "YES"))) ||
+          (variable &&
+           (!variable->value ||
+            !AsciiCaseInsensitiveEquals(*variable->value, "PRESELECT"))) ||
+          (contact && (!variable || !block.data.empty()))) {
+        if (!failure_)
+          InputFailure("unsupported-keyword", block.location,
+                       block.canonical_name, "",
+                       "Solid static output child is unsupported.");
+        return;
+      }
+      for (const auto& row : block.data) {
+        for (const auto& field : row.fields) {
+          const std::string token = CanonicalizeAscii(field);
+          if (!(node ? (token == "U" || token == "RF")
+                     : (token == "S" || token == "E"))) {
+            InputFailure("unsupported-keyword", row.location,
+                         block.canonical_name, field,
+                         "Solid output quantities must be physical supported "
+                         "components.");
+            return;
+          }
+        }
+      }
+    }
     if (step_.frequency) {
       const std::string_view required_variable =
           block.canonical_name == "NODE OUTPUT" ? "PRESELECT" : "ALL";
@@ -3001,16 +3291,32 @@ class DomainMappingContext::Impl {
                      "A material must own exactly one ELASTIC row.");
         return;
       }
-      if (model_element_family_ == ElementFamily::kShell) {
+      if (model_element_family_ == ElementFamily::kShell ||
+          model_element_family_ == ElementFamily::kSolid) {
         if (!(material.youngs_modulus > 0.0) ||
             !(material.poisson_ratio > -1.0) ||
             !(material.poisson_ratio < 0.5)) {
-          ModelFailure(
-              "invalid-shell-material", material.elastic_location, "ELASTIC",
-              material.name,
-              "Shell isotropic elasticity requires E>0 and -1<nu<0.5.");
+          ModelFailure(model_element_family_ == ElementFamily::kSolid
+                           ? "invalid-solid-material"
+                           : "invalid-shell-material",
+                       material.elastic_location, "ELASTIC", material.name,
+                       "Isotropic elasticity requires E>0 and -1<nu<0.5.");
           return;
         }
+        if (model_element_family_ == ElementFamily::kSolid) {
+          const double mu =
+              material.youngs_modulus / (2.0 * (1.0 + material.poisson_ratio));
+          const double lambda = material.youngs_modulus *
+                                material.poisson_ratio /
+                                ((1.0 + material.poisson_ratio) *
+                                 (1.0 - 2.0 * material.poisson_ratio));
+          if (!std::isfinite(mu) || !std::isfinite(lambda)) {
+            ModelFailure("invalid-solid-material", material.elastic_location,
+                         "ELASTIC", material.name,
+                         "Solid Lame constants must be finite.");
+            return;
+          }
+        }
         definition_.materials.push_back({material.name, material.youngs_modulus,
                                          material.poisson_ratio,
                                          material.location});
@@ -3063,6 +3369,16 @@ class DomainMappingContext::Impl {
                    "PHYSICAL CONSTANTS is supported only by thermal input.");
       return;
     }
+    if (!step_.frequency && !step_.dynamic &&
+        model_element_family_ == ElementFamily::kSolid) {
+      for (std::size_t index = 0U; index < materials_.size(); ++index) {
+        if (materials_[index].density)
+          definition_.densities.push_back({static_cast<EntityIndex>(index),
+                                           *materials_[index].density,
+                                           materials_[index].density_location});
+      }
+      return;
+    }
     if (!step_.frequency && !step_.dynamic) {
       if (std::any_of(materials_.begin(), materials_.end(),
                       [](const RawMaterial& material) {
@@ -3090,10 +3406,11 @@ class DomainMappingContext::Impl {
         }
       }
     }
-    if (model_element_family_ != ElementFamily::kShell) {
+    if (model_element_family_ != ElementFamily::kShell &&
+        model_element_family_ != ElementFamily::kSolid) {
       InputFailure("unsupported-analysis-procedure", step_.location,
                    step_.frequency ? "FREQUENCY" : "DYNAMIC", step_.name_raw,
-                   "The procedure requires the approved shell model family.");
+                   "The procedure requires an approved Shell or Solid model.");
       return;
     }
     if (!element_surfaces_.empty()) {
@@ -3112,6 +3429,10 @@ class DomainMappingContext::Impl {
             break;
           }
         }
+        for (const auto& section : definition_.solid_sections) {
+          if (section.MaterialIndex() == static_cast<EntityIndex>(index))
+            active = true;
+        }
         if (active) {
           ModelFailure(
               "missing-material-density", material.location, "MATERIAL",
@@ -3196,7 +3517,8 @@ class DomainMappingContext::Impl {
          ++part_index) {
       const RawPart& part = parts_[part_index];
       if (part.nodes.empty() || part.elements.empty() ||
-          (!shell_model && part.sections.empty())) {
+          (!shell_model && model_element_family_ != ElementFamily::kSolid &&
+           part.sections.empty())) {
         InputFailure("invalid-model-cardinality", part.location, "PART",
                      part.name,
                      "A part requires nodes, elements, and its approved "
@@ -3245,6 +3567,45 @@ class DomainMappingContext::Impl {
       }
       definition_.parts.push_back(std::move(part_definition));
 
+      if (model_element_family_ == ElementFamily::kSolid) {
+        auto& assignments = part_shell_section_assignments_[part_index];
+        for (const auto& section : part.solid_sections) {
+          const auto* element_set =
+              FindSet(part.element_sets, section.element_set_name);
+          const auto material = FindMaterialIndex(section.material_name);
+          if (!element_set || !material) {
+            InputFailure("unresolved-solid-section", section.location,
+                         "SOLID SECTION", section.element_set_name,
+                         "Solid ELSET and MATERIAL must resolve.");
+            return;
+          }
+          const auto index =
+              static_cast<EntityIndex>(definition_.solid_sections.size());
+          definition_.solid_sections.emplace_back(
+              SourceEntityId{part.name, static_cast<std::int64_t>(index),
+                             section.element_set_name},
+              section.element_set_name, *material, section.location);
+          for (const auto label : element_set->members) {
+            if (!assignments.emplace(label, std::make_pair(index, *material))
+                     .second) {
+              InputFailure(
+                  "invalid-solid-section-assignment", section.location,
+                  "SOLID SECTION", std::to_string(label),
+                  "Solid elements require exactly one section assignment.");
+              return;
+            }
+          }
+        }
+        for (const auto& element : part.elements) {
+          if (assignments.find(element.label) == assignments.end()) {
+            InputFailure("invalid-solid-section-assignment", element.location,
+                         "ELEMENT", element.label_text,
+                         "A Solid section assignment is missing.");
+            return;
+          }
+        }
+        continue;
+      }
       if (shell_model) {
         auto& assignments = part_shell_section_assignments_[part_index];
         for (const auto& section : part.shell_sections) {
@@ -3475,6 +3836,36 @@ class DomainMappingContext::Impl {
                assignment->second.second,
                assignment->second.first,
                raw_element.location});
+        } else if (raw_element.type == RawElement::Type::kC3d8) {
+          std::array<EntityIndex, 8> connected_nodes{};
+          for (std::size_t node = 0U; node < connected_nodes.size(); ++node) {
+            const auto found = node_indices.find(raw_element.node_labels[node]);
+            if (found == node_indices.end()) {
+              InputFailure("invalid-solid-connectivity", raw_element.location,
+                           "ELEMENT", raw_element.label_text,
+                           "Solid nodes must resolve.");
+              return;
+            }
+            connected_nodes[node] = found->second;
+          }
+          const auto& assignments =
+              part_shell_section_assignments_[PartIndex(*part)];
+          const auto assignment = assignments.find(raw_element.label);
+          if (assignment == assignments.end() ||
+              definition_.solid_elements.size() >
+                  std::numeric_limits<EntityIndex>::max()) {
+            InputFailure("invalid-solid-section-assignment",
+                         raw_element.location, "ELEMENT",
+                         raw_element.label_text,
+                         "Solid assignment must resolve.");
+            return;
+          }
+          index = static_cast<EntityIndex>(definition_.solid_elements.size());
+          definition_.solid_elements.emplace_back(
+              SourceEntityId{raw_instance.name, raw_element.label,
+                             raw_element.label_text},
+              connected_nodes, assignment->second.second,
+              assignment->second.first, raw_element.location);
         } else {
           std::array<EntityIndex, 4> connected_nodes{};
           for (std::size_t node = 0U; node < connected_nodes.size(); ++node) {
@@ -4048,6 +4439,47 @@ class DomainMappingContext::Impl {
     const SourceTargetIndex target_index = BuildSourceTargetIndex();
     const SourceTargetResolver target_resolver{target_index};
 
+    if (model_element_family_ == ElementFamily::kSolid) {
+      std::vector<PrescribedDisplacementDefinition> physical;
+      for (auto boundary : boundaries) {
+        if (!ResolveNodeTarget(target_resolver, boundary.target,
+                               boundary.location, "BOUNDARY"))
+          return;
+        if (boundary.last_dof > 3) {
+          if (boundary.value != 0.0) {
+            InputFailure("unsupported-solid-rotation-boundary",
+                         boundary.location, "BOUNDARY", boundary.target,
+                         "Solid rotational boundaries must be exact zero to be "
+                         "inactive.");
+            return;
+          }
+          definition_.warnings.push_back(
+              {Severity::kWarning, "inactive-solid-rotation-boundary",
+               boundary.location, "BOUNDARY", boundary.target,
+               "Exact-zero rotational boundary DOFs " +
+                   std::to_string(std::max(4, boundary.first_dof)) + ".." +
+                   std::to_string(boundary.last_dof) +
+                   " are inactive; Solid equations contain translations "
+                   "only."});
+          boundary.last_dof = 3;
+        }
+        if (boundary.first_dof <= boundary.last_dof)
+          physical.push_back(std::move(boundary));
+      }
+      boundaries = std::move(physical);
+      std::vector<bool> active(definition_.nodes.size(), false);
+      for (const auto& element : definition_.solid_elements)
+        for (const auto node : element.node_indices) active[node] = true;
+      for (std::size_t node = 0U; node < active.size(); ++node) {
+        if (!active[node]) {
+          ModelFailure("unused-solid-node", definition_.nodes[node].location,
+                       "NODE",
+                       definition_.nodes[node].source_id.source_label_text,
+                       "Every Solid node must connect to a C3D8 element.");
+          return;
+        }
+      }
+    }
     std::map<std::pair<EntityIndex, int>, double> prescribed_values;
     for (const auto& boundary : boundaries) {
       auto target = ResolveNodeTarget(target_resolver, boundary.target,
@@ -4115,10 +4547,15 @@ class DomainMappingContext::Impl {
     // Static time-control values are provenance only: V0 creates exactly
     // the canonical final frame 0 and performs no increment loop here.
     definition_.steps.push_back(
-        {"Step-1", std::move(boundaries), step_.loads,
-         std::move(surface_pressure_loads), step_.procedure_kind, step_.nlgeom,
-         step_.static_values[0], step_.static_values[1], step_.static_values[2],
-         step_.static_values[3], step_.location});
+        {model_element_family_ == ElementFamily::kSolid ? step_.name_raw
+                                                        : "Step-1",
+         std::move(boundaries), step_.loads, std::move(surface_pressure_loads),
+         step_.procedure_kind, step_.nlgeom, step_.static_values[0],
+         step_.static_values[1], step_.static_values[2], step_.static_values[3],
+         step_.location});
+    definition_.steps.back().direct = step_.static_direct;
+    definition_.steps.back().increment_count = step_.static_increment_count;
+    definition_.steps.back().maximum_increments = step_.maximum_increments;
   }
 
   const ParsedInput& input_;

src/fesa/loads/concentrated_nodal_load.cpp

@@ -30,15 +30,18 @@ ConcentratedNodalLoad::ConcentratedNodalLoad(
       global_components_{global_components},
       source_order_{source_order} {}
 
-ConcentratedNodalLoad::ConcentratedNodalLoad(SourceTargetQuery target,
-                                             const int source_dof,
-                                             const double magnitude,
-                                             const std::size_t source_order,
-                                             SourceLocation location)
+ConcentratedNodalLoad::ConcentratedNodalLoad(
+    SourceTargetQuery target, const int source_dof, const double magnitude,
+    const std::size_t source_order, SourceLocation location,
+    std::optional<EntityIndex> amplitude_index, std::string amplitude_name_raw,
+    SourceLocation amplitude_location)
     : target_{std::move(target)},
       source_order_{source_order},
       location_{std::move(location)},
-      source_dof_{source_dof} {
+      source_dof_{source_dof},
+      amplitude_index_{amplitude_index},
+      amplitude_name_raw_{std::move(amplitude_name_raw)},
+      amplitude_location_{std::move(amplitude_location)} {
   if (source_dof >= 1 && source_dof <= static_cast<int>(kDofsPerNode)) {
     global_components_[static_cast<std::size_t>(source_dof - 1)] = magnitude;
   }
@@ -47,6 +50,33 @@ ConcentratedNodalLoad::ConcentratedNodalLoad(SourceTargetQuery target,
 Result<std::vector<LoadContribution>>
 ConcentratedNodalLoad::ComputeContributions(const LoadContext& context) const {
   const std::string& identity = target_.target_name_or_label;
+  const std::size_t components = context.dof_manager.ComponentsPerNode();
+  if (context.dof_manager.Profile() == DofProfile::kThermal ||
+      (source_dof_ != 0 && source_dof_ > static_cast<int>(components))) {
+    return Result<std::vector<LoadContribution>>::Failure(LoadFailure(
+        "invalid-load-dof", location_, identity,
+        "The source load component is inactive for this physical profile."));
+  }
+  for (std::size_t component = components; component < kDofsPerNode;
+       ++component) {
+    if (global_components_[component] != 0.0) {
+      return Result<std::vector<LoadContribution>>::Failure(
+          LoadFailure("invalid-load-dof", location_, identity,
+                      "A Solid load cannot contain rotational components."));
+    }
+  }
+  double amplitude = 1.0;
+  if (amplitude_index_) {
+    if (!context.domain.IsSolid() || context.domain.Dynamic() == nullptr ||
+        *amplitude_index_ >= context.domain.Amplitudes().size() ||
+        !std::isfinite(context.step_time) || context.step_time < 0.0) {
+      return Result<std::vector<LoadContribution>>::Failure(
+          LoadFailure("invalid-load-amplitude", location_, identity,
+                      "Amplitude requires a valid Solid dynamic endpoint."));
+    }
+    amplitude = context.domain.Amplitudes()[*amplitude_index_].Evaluate(
+        context.step_time);
+  }
   if (source_dof_ != 0 &&
       (source_dof_ < 1 || source_dof_ > static_cast<int>(kDofsPerNode))) {
     return Result<std::vector<LoadContribution>>::Failure(LoadFailure(
@@ -76,7 +106,7 @@ ConcentratedNodalLoad::ComputeContributions(const LoadContext& context) const {
 
   std::vector<unsigned char> seen(context.domain.Nodes().size(), 0U);
   std::vector<LoadContribution> contributions;
-  contributions.reserve(resolved.Value().size() * kDofsPerNode);
+  contributions.reserve(resolved.Value().size() * components);
   for (const auto& target : resolved.Value()) {
     const EntityIndex node = target.entity_index;
     if (node >= context.domain.Nodes().size() || seen[node] != 0U) {
@@ -86,13 +116,19 @@ ConcentratedNodalLoad::ComputeContributions(const LoadContext& context) const {
           "identities."));
     }
     seen[node] = 1U;
-    for (std::size_t component = 0U; component < kDofsPerNode; ++component) {
+    for (std::size_t component = 0U; component < components; ++component) {
+      const double value = global_components_[component] * amplitude;
+      if (!std::isfinite(value)) {
+        return Result<std::vector<LoadContribution>>::Failure(
+            LoadFailure("nonfinite-load-value", location_, identity,
+                        "Sampled load magnitude must remain finite."));
+      }
       try {
         contributions.push_back(
             {source_order_,
              context.dof_manager.FullDof(node,
                                          static_cast<DofComponent>(component)),
-             global_components_[component]});
+             value});
       } catch (const std::out_of_range&) {
         return Result<std::vector<LoadContribution>>::Failure(LoadFailure(
             "invalid-load-target", location_, identity,

src/fesa/model/domain.cpp

@@ -1,10 +1,13 @@
 #include "fesa/model/domain.h"
 
-#include <cstddef>
+#include <algorithm>
+#include <array>
 #include <cmath>
+#include <cstddef>
 #include <functional>
 #include <map>
 #include <memory>
+#include <set>
 #include <string>
 #include <utility>
 
@@ -48,8 +51,10 @@ Status ValidateThermalTargets(
 
 Status ValidateThermalDefinition(const ModelDefinition& definition) {
   const bool has_structural = !definition.elements.empty() ||
-                              !definition.shell_elements.empty();
-  const bool has_thermal_data = !definition.thermal_materials.empty() ||
+                              !definition.shell_elements.empty() ||
+                              !definition.solid_elements.empty();
+  const bool has_thermal_data =
+      !definition.thermal_materials.empty() ||
       !definition.thermal_sections.empty() ||
       definition.thermal_step.has_value() ||
       !definition.thermal_initial_conditions.empty() ||
@@ -161,6 +166,180 @@ Status ValidateThermalDefinition(const ModelDefinition& definition) {
   return Status::Ok();
 }
 
+/// @brief Checks Solid semantic candidates before immutable ownership starts.
+Status ValidateSolidDefinition(ModelDefinition& definition) {
+  const auto fail = [](const SourceLocation& location,
+                       const std::string& identity,
+                       const std::string& message) {
+    return Status::Failure(FailureCategory::kModel,
+                           {{Severity::kError, "invalid-solid-definition",
+                             location, "SOLID", identity, message}});
+  };
+  if (definition.solid_elements.empty()) {
+    if (!definition.solid_sections.empty() || !definition.amplitudes.empty())
+      return fail({}, "C3D8", "Solid definitions require a C3D8 model.");
+    return Status::Ok();
+  }
+  if (!definition.elements.empty() || !definition.shell_elements.empty() ||
+      !definition.thermal_elements.empty() || definition.thermal_step ||
+      !definition.sections.empty() || !definition.shell_sections.empty() ||
+      !definition.element_surfaces.empty()) {
+    return fail({}, "C3D8",
+                "Solid models cannot mix element or section families.");
+  }
+  if (definition.steps.size() + (definition.frequency_step ? 1U : 0U) +
+          (definition.dynamic_step ? 1U : 0U) !=
+      1U) {
+    return fail({}, "STEP", "Solid models require exactly one procedure.");
+  }
+  std::vector<bool> active(definition.nodes.size(), false);
+  std::set<std::pair<std::string, std::int64_t>> node_ids;
+  for (const auto& node : definition.nodes) {
+    if (!node_ids
+             .emplace(node.source_id.instance_name, node.source_id.source_label)
+             .second)
+      return fail(node.location, node.source_id.source_label_text,
+                  "Node identity is duplicated.");
+    for (const double coordinate : node.coordinates)
+      if (!std::isfinite(coordinate))
+        return fail(node.location, node.source_id.source_label_text,
+                    "Solid coordinates must be finite.");
+  }
+  std::set<std::pair<std::string, std::int64_t>> element_ids;
+  std::set<EntityIndex> active_materials;
+  for (const auto& element : definition.solid_elements) {
+    if (!element_ids
+             .emplace(element.source_id.instance_name,
+                      element.source_id.source_label)
+             .second ||
+        element.section_index >= definition.solid_sections.size() ||
+        element.material_index >= definition.materials.size()) {
+      return fail(
+          element.location, element.source_id.source_label_text,
+          "Solid identity, section, and material must resolve uniquely.");
+    }
+    if (definition.solid_sections[element.section_index].MaterialIndex() !=
+        element.material_index)
+      return fail(element.location, element.source_id.source_label_text,
+                  "Solid material assignment conflicts.");
+    active_materials.insert(element.material_index);
+    std::set<EntityIndex> distinct;
+    for (const auto node : element.node_indices) {
+      if (node >= active.size() || !distinct.insert(node).second)
+        return fail(element.location, element.source_id.source_label_text,
+                    "Solid connectivity requires eight distinct active nodes.");
+      active[node] = true;
+    }
+  }
+  for (std::size_t node = 0U; node < active.size(); ++node)
+    if (!active[node])
+      return fail(definition.nodes[node].location,
+                  definition.nodes[node].source_id.source_label_text,
+                  "Solid nodes must be connected.");
+  for (const auto& section : definition.solid_sections)
+    if (section.MaterialIndex() >= definition.materials.size() ||
+        section.Name().empty())
+      return fail(section.Location(), section.Name(),
+                  "Solid material assignment is invalid.");
+  for (const auto index : active_materials) {
+    const auto& material = definition.materials[index];
+    const double young = material.YoungsModulus();
+    const double nu = material.PoissonsRatio();
+    const double mu = young / (2.0 * (1.0 + nu));
+    const double lambda = young * nu / ((1.0 + nu) * (1.0 - 2.0 * nu));
+    if (!std::isfinite(young) || !(young > 0.0) || !std::isfinite(nu) ||
+        !(nu > -1.0 && nu < 0.5) || !std::isfinite(mu) ||
+        !std::isfinite(lambda))
+      return fail(material.Location(), material.Name(),
+                  "Solid isotropic constants are invalid.");
+  }
+  std::set<EntityIndex> density_materials;
+  for (const auto& density : definition.densities) {
+    if (density.material_index >= definition.materials.size() ||
+        !std::isfinite(density.rho) || !(density.rho > 0.0) ||
+        !density_materials.insert(density.material_index).second)
+      return fail(density.location, "DENSITY",
+                  "Solid density must be finite positive and unique.");
+  }
+  if (definition.dynamic_step || definition.frequency_step)
+    for (const auto material : active_materials)
+      if (density_materials.count(material) == 0U)
+        return fail({}, "DENSITY",
+                    "Solid frequency and dynamic materials require density.");
+  std::set<std::string> amplitude_names;
+  for (const auto& amplitude : definition.amplitudes) {
+    if (!definition.dynamic_step || amplitude.name_raw.empty() ||
+        amplitude.name_canonical.empty() ||
+        !amplitude_names.insert(amplitude.name_canonical).second ||
+        amplitude.points.empty())
+      return fail(amplitude.location, amplitude.name_raw,
+                  "Solid amplitude identity is invalid.");
+    double previous = -1.0;
+    for (const auto& point : amplitude.points) {
+      if (!std::isfinite(point[0]) || !std::isfinite(point[1]) ||
+          point[0] < 0.0 || !(point[0] > previous))
+        return fail(amplitude.location, amplitude.name_raw,
+                    "Solid amplitude pairs are invalid.");
+      previous = point[0];
+    }
+  }
+  const auto validate_boundaries = [&fail](const auto& boundaries,
+                                           bool homogeneous) {
+    for (const auto& boundary : boundaries) {
+      if (boundary.first_dof < 1 || boundary.last_dof < boundary.first_dof ||
+          boundary.last_dof > 3 || !std::isfinite(boundary.value) ||
+          (homogeneous && boundary.value != 0.0))
+        return fail(boundary.location, boundary.target,
+                    "Solid physical boundaries require DOF1..3.");
+    }
+    return Status::Ok();
+  };
+  const auto validate_loads = [&fail, &definition](const auto& loads,
+                                                   bool dynamic) {
+    for (const auto& load : loads) {
+      if (load.dof < 1 || load.dof > 3 || !std::isfinite(load.magnitude) ||
+          (load.amplitude_index &&
+           (!dynamic || *load.amplitude_index >= definition.amplitudes.size())))
+        return fail(load.location, load.target,
+                    "Solid load component or amplitude is invalid.");
+    }
+    return Status::Ok();
+  };
+  if (definition.frequency_step)
+    return validate_boundaries(definition.frequency_step->boundaries, true);
+  if (definition.dynamic_step) {
+    const auto& dynamic = *definition.dynamic_step;
+    if (!std::isfinite(dynamic.initial_increment) ||
+        !(dynamic.initial_increment > 0.0) ||
+        !std::isfinite(dynamic.time_period) || !(dynamic.time_period > 0.0) ||
+        dynamic.increment_count == 0U ||
+        dynamic.increment_count > dynamic.maximum_increments ||
+        dynamic.initial_increment *
+                static_cast<double>(dynamic.increment_count) !=
+            dynamic.time_period ||
+        dynamic.alpha != -0.05 || dynamic.beta != 0.275625 ||
+        dynamic.gamma != 0.55)
+      return fail(dynamic.data_location, dynamic.source_step_name_raw,
+                  "Solid dynamic controls are invalid.");
+    const auto status = validate_boundaries(dynamic.boundaries, true);
+    if (!status.IsOk()) return status;
+    return validate_loads(dynamic.loads, true);
+  }
+  const auto& step = definition.steps[0];
+  if (step.direct &&
+      (!std::isfinite(step.initial_increment) ||
+       !(step.initial_increment > 0.0) || !std::isfinite(step.time_period) ||
+       !(step.time_period > 0.0) || step.increment_count == 0U ||
+       step.increment_count > step.maximum_increments ||
+       step.initial_increment * static_cast<double>(step.increment_count) !=
+           step.time_period))
+    return fail(step.location, step.name,
+                "Solid static fixed schedule is invalid.");
+  const auto status = validate_boundaries(step.boundaries, false);
+  if (!status.IsOk()) return status;
+  return validate_loads(step.loads, false);
+}
+
 }  // namespace
 
 StepDefinition::StepDefinition(StaticStepDefinition definition)
@@ -192,12 +371,17 @@ StepDefinition::StepDefinition(StaticStepDefinition definition)
     auto& load = definition.loads[source_order];
     auto owned = std::make_unique<ConcentratedNodalLoad>(
         SourceTargetQuery{SourceEntityKind::kNode, "", load.target}, load.dof,
-        load.magnitude, source_order, std::move(load.location));
+        load.magnitude, source_order, std::move(load.location),
+        load.amplitude_index, std::move(load.amplitude_name_raw),
+        std::move(load.amplitude_location));
     loads_view_.push_back(std::cref(*owned));
     concentrated_loads_view_.Add(*owned);
     loads_.push_back(std::move(owned));
   }
   surface_pressure_loads_ = std::move(definition.surface_pressure_loads);
+  direct_static_ = definition.direct;
+  increment_count_ = definition.increment_count;
+  maximum_increments_ = definition.maximum_increments;
 }
 
 StepDefinition::StepDefinition(FrequencyStepDefinition definition)
@@ -227,8 +411,10 @@ StepDefinition::StepDefinition(FrequencyStepDefinition definition)
 
 StepDefinition::StepDefinition(DynamicStepDefinition definition)
     : name_{definition.source_step_name_raw},
-      procedure_kind_{StaticProcedureKind::kNonlinearFullNewton},
-      nlgeom_{true},
+      procedure_kind_{definition.nlgeom
+                          ? StaticProcedureKind::kNonlinearFullNewton
+                          : StaticProcedureKind::kLinearSmallDisplacement},
+      nlgeom_{definition.nlgeom},
       initial_increment_{definition.initial_increment},
       time_period_{definition.time_period},
       minimum_increment_{definition.initial_increment},
@@ -255,7 +441,9 @@ StepDefinition::StepDefinition(DynamicStepDefinition definition)
     auto& load = dynamic_->loads[source_order];
     auto owned = std::make_unique<ConcentratedNodalLoad>(
         SourceTargetQuery{SourceEntityKind::kNode, "", load.target}, load.dof,
-        load.magnitude, source_order, std::move(load.location));
+        load.magnitude, source_order, std::move(load.location),
+        load.amplitude_index, std::move(load.amplitude_name_raw),
+        std::move(load.amplitude_location));
     loads_view_.push_back(std::cref(*owned));
     concentrated_loads_view_.Add(*owned);
     loads_.push_back(std::move(owned));
@@ -325,11 +513,21 @@ double StepDefinition::MaximumIncrement() const noexcept {
   return maximum_increment_;
 }
 
+bool StepDefinition::IsDirectStatic() const noexcept { return direct_static_; }
+std::uint32_t StepDefinition::IncrementCount() const noexcept {
+  return increment_count_;
+}
+std::uint32_t StepDefinition::MaximumIncrements() const noexcept {
+  return maximum_increments_;
+}
+
 const SourceLocation& StepDefinition::Location() const noexcept {
   return location_;
 }
 
 Result<Domain> Domain::Create(ModelDefinition definition) {
+  const Status solid_status = ValidateSolidDefinition(definition);
+  if (!solid_status.IsOk()) return Result<Domain>::Failure(solid_status);
   const Status thermal_status = ValidateThermalDefinition(definition);
   if (!thermal_status.IsOk()) return Result<Domain>::Failure(thermal_status);
   return Result<Domain>::Success(Domain{std::move(definition)});
@@ -354,6 +552,23 @@ const DomainCollectionView<Mitc4ShellDefinition>& Domain::ShellElements()
   return shell_elements_view_;
 }
 
+const DomainCollectionView<Hex8Definition>& Domain::SolidElements()
+    const noexcept {
+  return solid_elements_view_;
+}
+const DomainCollectionView<SolidSection>& Domain::SolidSections()
+    const noexcept {
+  return solid_sections_view_;
+}
+bool Domain::IsSolid() const noexcept {
+  return !solid_elements_view_.Empty() &&
+         solid_elements_view_.Size() == elements_view_.Size();
+}
+const std::vector<TabularAmplitudeDefinition>& Domain::Amplitudes()
+    const noexcept {
+  return definition_.amplitudes;
+}
+
 const DomainCollectionView<Material>& Domain::Materials() const noexcept {
   return materials_view_;
 }
@@ -496,6 +711,14 @@ Domain::Domain(ModelDefinition definition)
     element_properties_.push_back(std::move(owned));
   }
   definition_.shell_sections.clear();
+  const std::size_t solid_property_offset = element_properties_.size();
+  for (auto& section : definition_.solid_sections) {
+    auto owned = std::make_unique<SolidSection>(std::move(section));
+    properties_view_.Add(*owned);
+    solid_sections_view_.Add(*owned);
+    element_properties_.push_back(std::move(owned));
+  }
+  definition_.solid_sections.clear();
 
   element_definitions_.reserve(definition_.elements.size() +
                                definition_.shell_elements.size());
@@ -517,6 +740,16 @@ Domain::Domain(ModelDefinition definition)
     element_definitions_.push_back(std::move(owned));
   }
   definition_.shell_elements.clear();
+  for (auto& element : definition_.solid_elements) {
+    element.SynchronizeNodeIndices();
+    element.SetPropertyIndex(static_cast<EntityIndex>(solid_property_offset +
+                                                      element.section_index));
+    auto owned = std::make_unique<Hex8Definition>(std::move(element));
+    elements_view_.Add(*owned);
+    solid_elements_view_.Add(*owned);
+    element_definitions_.push_back(std::move(owned));
+  }
+  definition_.solid_elements.clear();
   for (auto& element : definition_.thermal_elements) {
     const EntityIndex material_index = static_cast<EntityIndex>(
         structural_material_count +

tests/unit/io/abaqus/hex8_semantics_test.cpp

@@ -0,0 +1,555 @@
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <filesystem>
+#include <fstream>
+#include <functional>
+#include <limits>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+#include "fesa/analysis/analysis_model.h"
+#include "fesa/assembly/load_assembler.h"
+#include "fesa/assembly/parallel_for.h"
+#include "fesa/assembly/sparse_assembler.h"
+#include "fesa/fem/dof_manager.h"
+#include "fesa/io/abaqus/domain_mapper.h"
+#include "fesa/io/abaqus/input_reader.h"
+
+namespace {
+std::string Deck(const std::string& procedure = "*Static\n1,1,1,1\n",
+                 const std::string& boundary = "10,1,3\n",
+                 const std::string& extra = "") {
+  return "*Part,name=P\n*Node\n10,0,0,0\n20,1,0,0\n30,1,1,0\n40,0,1,0\n"
+         "50,0,0,1\n60,1,0,1\n70,1,1,1\n80,0,1,1\n"
+         "*Element,type=C3D8,elset=E\n99,10,20,30,40,50,60,70,80\n"
+         "*Solid Section,elset=E,material=M\n,\n*End Part\n"
+         "*Assembly,name=A\n*Instance,name=I,part=P\n*End Instance\n"
+         "*End Assembly\n*Material,name=M\n*Elastic\n1000,.3\n" +
+         extra + "*Step,name=Solid,inc=100\n" + procedure +
+         (boundary.empty() ? "" : "*Boundary\n" + boundary) + "*End Step\n";
+}
+fesa::Result<fesa::Domain> Map(const std::string& text) {
+  const auto path =
+      std::filesystem::temp_directory_path() / "fesa-hex8-semantics.inp";
+  {
+    std::ofstream out{path};
+    out << text;
+  }
+  auto syntax = fesa::AbaqusInputReader{}.Read(path);
+  std::filesystem::remove(path);
+  if (!syntax.HasValue())
+    return fesa::Result<fesa::Domain>::Failure(syntax.GetStatus());
+  return fesa::AbaqusDomainMapper{}.Map(syntax.Value());
+}
+TEST(Hex8Semantics, MapsEightSourceNodesAndExactlyThreePhysicalDofs) {
+  auto domain = Map(Deck());
+  ASSERT_TRUE(domain.HasValue())
+      << (domain.GetStatus().Diagnostics().empty()
+              ? ""
+              : domain.GetStatus().Diagnostics()[0].message);
+  ASSERT_EQ(domain.Value().Elements().Size(), 1U);
+  EXPECT_EQ(domain.Value().Elements()[0].SourceElementType(), "C3D8");
+  EXPECT_EQ(domain.Value().Elements()[0].SourceId().source_label, 99);
+  EXPECT_EQ(domain.Value().Elements()[0].NodeIndices().size(), 8U);
+  auto model = fesa::AnalysisModel::Create(domain.Value());
+  ASSERT_TRUE(model.HasValue());
+  auto dofs = fesa::DofManager::Create(model.Value());
+  ASSERT_TRUE(dofs.HasValue());
+  EXPECT_EQ(dofs.Value().FullDofCount(), 24U);
+  EXPECT_EQ(dofs.Value().ConstrainedDofCount(), 3U);
+}
+TEST(Hex8Semantics, InactiveZeroRotationsWarnAndDoNotCreateConstraints) {
+  auto domain = Map(Deck("*Static\n1,1,1,1\n", "10,1,6\n"));
+  ASSERT_TRUE(domain.HasValue())
+      << (domain.GetStatus().Diagnostics().empty()
+              ? ""
+              : domain.GetStatus().Diagnostics()[0].message);
+  EXPECT_EQ(domain.Value().Steps()[0].BoundaryConditions().size(), 3U);
+  ASSERT_FALSE(domain.Value().Warnings().empty());
+  EXPECT_EQ(domain.Value().Warnings().back().keyword, "BOUNDARY");
+  EXPECT_EQ(domain.Value().Warnings().back().entity_identity, "10");
+  EXPECT_GT(domain.Value().Warnings().back().location.line, 0U);
+}
+TEST(Hex8Semantics, RejectsNonzeroRotationsAndAllRotationalLoads) {
+  EXPECT_FALSE(Map(Deck("*Static\n1,1,1,1\n", "10,4,4,1\n")).HasValue());
+  EXPECT_FALSE(
+      Map(Deck("*Static\n1,1,1,1\n", "10,1,3\n*Cload\n20,4,0\n")).HasValue());
+}
+
+std::string Replace(std::string input, const std::string& from,
+                    const std::string& to) {
+  const auto position = input.find(from);
+  if (position == std::string::npos)
+    throw std::logic_error{"Missing mutation source"};
+  input.replace(position, from.size(), to);
+  return input;
+}
+TEST(Hex8Semantics, RotationNoOpPreservesPhysicalMapAndLoads) {
+  auto physical =
+      Map(Deck("*Static\n1,1,1,1\n", "10,1,3,0\n*Cload\n20,2,17\n"));
+  auto extra =
+      Map(Deck("*Static\n1,1,1,1\n", "10,1,6,0\n20,4,6,-0\n*Cload\n20,2,17\n"));
+  ASSERT_TRUE(physical.HasValue());
+  ASSERT_TRUE(extra.HasValue());
+  auto pm = fesa::AnalysisModel::Create(physical.Value());
+  auto em = fesa::AnalysisModel::Create(extra.Value());
+  auto pd = fesa::DofManager::Create(pm.Value());
+  auto ed = fesa::DofManager::Create(em.Value());
+  ASSERT_TRUE(pd.HasValue());
+  ASSERT_TRUE(ed.HasValue());
+  EXPECT_EQ(pd.Value().FreeDofs(), ed.Value().FreeDofs());
+  EXPECT_EQ(pd.Value().ConstrainedDofs(), ed.Value().ConstrainedDofs());
+  EXPECT_EQ(pd.Value().GetSparsePattern().column_indices,
+            ed.Value().GetSparsePattern().column_indices);
+  EXPECT_EQ(ed.Value().Profile(), fesa::DofProfile::kSolidStructural);
+  EXPECT_EQ(ed.Value().ComponentsPerNode(), 3U);
+  EXPECT_THROW(ed.Value().FullDof(0, fesa::DofComponent::kUrx),
+               std::out_of_range);
+  const auto& element = extra.Value().Elements()[0];
+  auto scatter = ed.Value().ElementScatter(
+      {element.SourceId(),
+       element.NodeIndices(),
+       {fesa::DofComponent::kUx, fesa::DofComponent::kUy,
+        fesa::DofComponent::kUz}});
+  ASSERT_TRUE(scatter.HasValue());
+  EXPECT_EQ(scatter.Value().size(), 24U);
+  EXPECT_EQ(scatter.Value().front(), 0U);
+  EXPECT_EQ(scatter.Value().back(), 23U);
+  auto pf = fesa::LoadAssembler::AssembleFullNodalLoad(pm.Value(), pd.Value());
+  auto ef = fesa::LoadAssembler::AssembleFullNodalLoad(em.Value(), ed.Value());
+  ASSERT_TRUE(pf.HasValue());
+  ASSERT_TRUE(ef.HasValue());
+  for (std::size_t i = 0; i < 24U; ++i) EXPECT_EQ(pf.Value()[i], ef.Value()[i]);
+}
+TEST(Hex8Semantics, RejectsTinyRotationBadTargetsOptionsAndDofRanges) {
+  for (const std::string row :
+       {"10,4,6,1e-100\n", "Missing,4,6,0\n", "10,0,3\n", "10,1,7\n"})
+    EXPECT_FALSE(Map(Deck("*Static\n1,1,1,1\n", row)).HasValue()) << row;
+  for (const std::string option : {"type=VELOCITY", "amplitude=A", "op=NEW"})
+    EXPECT_FALSE(
+        Map(Replace(Deck(), "*Boundary", "*Boundary," + option)).HasValue());
+  for (const std::string row : {"10,4,6\n", "10,4,6,0\n", "10,4,6,\n"}) {
+    auto result = Map(Deck("*Static\n1,1,1,1\n", row));
+    ASSERT_TRUE(result.HasValue()) << row;
+    EXPECT_TRUE(result.Value().Steps()[0].BoundaryConditions().empty());
+    ASSERT_EQ(result.Value().Warnings().size(), 1U);
+    EXPECT_EQ(result.Value().Warnings()[0].code,
+              "inactive-solid-rotation-boundary");
+    EXPECT_EQ(result.Value().Warnings()[0].severity, fesa::Severity::kWarning);
+  }
+}
+TEST(Hex8Semantics, AllowsEmptyFreeAndNoBoundaryModels) {
+  std::string all;
+  for (int node = 10; node <= 80; node += 10)
+    all += std::to_string(node) + ",1,6\n";
+  for (const auto& boundaries : {all, std::string{}}) {
+    auto domain = Map(Deck("*Static\n1,1,1,1\n", boundaries));
+    ASSERT_TRUE(domain.HasValue());
+    auto model = fesa::AnalysisModel::Create(domain.Value());
+    auto dofs = fesa::DofManager::Create(model.Value());
+    ASSERT_TRUE(dofs.HasValue());
+    EXPECT_EQ(dofs.Value().FullDofCount(), 24U);
+    EXPECT_EQ(dofs.Value().FreeDofCount(), boundaries.empty() ? 24U : 0U);
+  }
+}
+TEST(Hex8Semantics, RetainsStaticDensityTargetsAndDirectSchedule) {
+  auto domain =
+      Map(Deck("*Static,direct\n.1,1,\n", "10,1,3,.25\n", "*Density\n2\n"));
+  ASSERT_TRUE(domain.HasValue())
+      << (domain.GetStatus().Diagnostics().empty()
+              ? ""
+              : domain.GetStatus().Diagnostics()[0].message);
+  EXPECT_TRUE(domain.Value().IsSolid());
+  ASSERT_EQ(domain.Value().SolidSections().Size(), 1U);
+  EXPECT_EQ(domain.Value().SolidSections()[0].MaterialIndex(), 0U);
+  EXPECT_EQ(domain.Value().Densities()[0].rho, 2.0);
+  const auto& step = domain.Value().Steps()[0];
+  EXPECT_EQ(step.Name(), "Solid");
+  EXPECT_TRUE(step.IsDirectStatic());
+  EXPECT_EQ(step.IncrementCount(), 10U);
+  EXPECT_EQ(step.MaximumIncrements(), 100U);
+  auto model = fesa::AnalysisModel::Create(domain.Value());
+  auto dofs = fesa::DofManager::Create(model.Value());
+  EXPECT_EQ(dofs.Value().PrescribedValues()[0], .25);
+  for (const std::string values : {".3,1\n", "0,1\n", ".1,11\n"})
+    EXPECT_FALSE(Map(Deck("*Static,direct\n" + values)).HasValue());
+  EXPECT_FALSE(Map(Replace(Deck(), "1000,.3", "1000,.5")).HasValue());
+  EXPECT_FALSE(Map(Replace(Deck(), "1000,.3", "1000,-1")).HasValue());
+}
+TEST(Hex8Semantics, SamplesIndependentAmplitudeLoadsAtActualEndpoints) {
+  const std::string amplitudes =
+      "*Density\n2\n*Amplitude,name=A\n0,0,.1,1\n10,1\n"
+      "*Amplitude,name=B,definition=TABULAR,time=STEP "
+      "TIME,value=RELATIVE\n0,2,1,4\n";
+  const auto text = Deck("*Dynamic,direct\n.1,10,\n",
+                         "10,1,6\n*Cload,amplitude=a\n20,1,10\n"
+                         "*Cload,amplitude=B\n20,1,3\n*Cload\n20,1,5\n",
+                         amplitudes);
+  auto domain = Map(text);
+  ASSERT_TRUE(domain.HasValue())
+      << (domain.GetStatus().Diagnostics().empty()
+              ? ""
+              : domain.GetStatus().Diagnostics()[0].message);
+  ASSERT_EQ(domain.Value().Amplitudes().size(), 2U);
+  const auto& amplitude = domain.Value().Amplitudes()[0];
+  EXPECT_EQ(amplitude.name_raw, "A");
+  EXPECT_EQ(amplitude.Evaluate(0), 0);
+  EXPECT_EQ(amplitude.Evaluate(.05), .5);
+  EXPECT_EQ(amplitude.Evaluate(.1), 1);
+  EXPECT_EQ(amplitude.Evaluate(20), 1);
+  EXPECT_FALSE(domain.Value().Dynamic()->nlgeom);
+  EXPECT_EQ(domain.Value().Dynamic()->increment_count, 100U);
+  const auto& loads = domain.Value().Steps()[0].ConcentratedLoads();
+  EXPECT_EQ(loads[0].AmplitudeIndex(), std::optional<fesa::EntityIndex>{0U});
+  EXPECT_EQ(loads[1].AmplitudeIndex(), std::optional<fesa::EntityIndex>{1U});
+  EXPECT_EQ(loads[0].AmplitudeName(), "a");
+  EXPECT_GT(loads[0].AmplitudeLocation().line, 0U);
+  auto model = fesa::AnalysisModel::Create(domain.Value());
+  auto dofs = fesa::DofManager::Create(model.Value());
+  ASSERT_TRUE(dofs.HasValue());
+  for (double time : {0., .05, .1, 1., 10.}) {
+    auto load = fesa::LoadAssembler::AssembleFullNodalLoad(model.Value(),
+                                                           dofs.Value(), time);
+    ASSERT_TRUE(load.HasValue());
+    EXPECT_DOUBLE_EQ(load.Value()[3],
+                     amplitude.Evaluate(time) * 10 +
+                         domain.Value().Amplitudes()[1].Evaluate(time) * 3 + 5);
+  }
+  EXPECT_FALSE(Map(Replace(text, "10,1,6", "10,1,3,1e-100")).HasValue());
+  EXPECT_FALSE(
+      Map(Replace(text, "amplitude=a", "amplitude=missing")).HasValue());
+  EXPECT_TRUE(
+      Map(Replace(text, "name=Solid,inc=100", "name=Solid,nlgeom=YES,inc=100"))
+          .HasValue());
+}
+TEST(Hex8Semantics, RejectsAmplitudeOptionsDataAndCrossFamilyUse) {
+  const std::string prefix = "*Density\n2\n";
+  for (const std::string amplitude :
+       {"*Amplitude,name=A,time=TOTAL TIME\n0,0\n",
+        "*Amplitude,name=A,definition=SMOOTH STEP\n0,0\n",
+        "*Amplitude,name=A,value=ABSOLUTE\n0,0\n",
+        "*Amplitude,name=A,smooth=0\n0,0\n", "*Amplitude,name=A\n0,0,1\n",
+        "*Amplitude,name=A\n0,0,0,1\n", "*Amplitude,name=A\n1,0,0,1\n",
+        "*Amplitude,name=A\n-1,0\n", "*Amplitude,name=A\n0,nan\n",
+        "*Amplitude,name=A\n",
+        "*Amplitude,name=A\n0,0\n*Amplitude,name=a\n0,1\n"})
+    EXPECT_FALSE(
+        Map(Deck("*Dynamic,direct\n.1,1\n", "10,1,3\n", prefix + amplitude))
+            .HasValue())
+        << amplitude;
+  EXPECT_FALSE(
+      Map(Deck("*Static\n1,1,1,1\n", "10,1,3\n", "*Amplitude,name=A\n0,0\n"))
+          .HasValue());
+  EXPECT_FALSE(Map(Deck("*Dynamic,direct\n.1,1\n", "10,1,3\n")).HasValue());
+}
+TEST(Hex8Semantics, RejectsAliasesConnectivityThicknessAndMixedModels) {
+  for (const std::string type : {"C3D8R", "C3D8I", "C3D8H", "C3D20"})
+    EXPECT_FALSE(Map(Replace(Deck(), "type=C3D8", "type=" + type)).HasValue());
+  EXPECT_FALSE(Map(Replace(Deck(), "99,10,20,30,40,50,60,70,80",
+                           "99,10,20,30,40,50,60,70,70"))
+                   .HasValue());
+  EXPECT_FALSE(Map(Replace(Deck(), "99,10,20,30,40,50,60,70,80",
+                           "99,10,20,30,40,50,60,70,999"))
+                   .HasValue());
+  EXPECT_FALSE(
+      Map(Replace(Deck(), "material=M\n,", "material=M\n2")).HasValue());
+  EXPECT_FALSE(Map(Replace(Deck(), "*Solid Section",
+                           "*Element,type=S4\n100,10,20,30,40\n*Solid Section"))
+                   .HasValue());
+}
+TEST(Hex8Semantics, PreservesShellSixComponentProfile) {
+  auto text = Replace(Deck(), "50,0,0,1\n60,1,0,1\n70,1,1,1\n80,0,1,1\n", "");
+  text = Replace(text, "*Element,type=C3D8,elset=E\n99,10,20,30,40,50,60,70,80",
+                 "*Element,type=S4\n99,10,20,30,40\n*Elset,elset=E\n99");
+  text = Replace(text, "*Solid Section,elset=E,material=M\n,",
+                 "*Shell Section,elset=E,material=M\n.1");
+  auto domain = Map(text);
+  ASSERT_TRUE(domain.HasValue());
+  auto model = fesa::AnalysisModel::Create(domain.Value());
+  auto dofs = fesa::DofManager::Create(model.Value());
+  ASSERT_TRUE(dofs.HasValue());
+  EXPECT_EQ(dofs.Value().Profile(), fesa::DofProfile::kStructural);
+  EXPECT_EQ(dofs.Value().ComponentsPerNode(), 6U);
+  EXPECT_EQ(dofs.Value().FullDofCount(), 24U);
+  EXPECT_EQ(dofs.Value().FullDof(1, fesa::DofComponent::kUrx), 9U);
+}
+TEST(Hex8Semantics, MapsAllFiveUnmodifiedRequiredSourceDecks) {
+  auto root = std::filesystem::path{__FILE__}.parent_path();
+  for (int i = 0; i < 4; ++i) root = root.parent_path();
+  for (const std::string name :
+       {"hexa_linearstatic.inp", "hexa_nonlinearstatic.inp", "hexa_freq.inp",
+        "hexa_dynlinear.inp", "hexa_dynnonlinear.inp"}) {
+    auto syntax =
+        fesa::AbaqusInputReader{}.Read(root / "reference/hexa" / name);
+    ASSERT_TRUE(syntax.HasValue()) << name;
+    auto domain = fesa::AbaqusDomainMapper{}.Map(syntax.Value());
+    ASSERT_TRUE(domain.HasValue())
+        << name << ": "
+        << (domain.GetStatus().Diagnostics().empty()
+                ? ""
+                : domain.GetStatus().Diagnostics()[0].message);
+    EXPECT_EQ(domain.Value().SolidElements().Size(), 300U);
+    EXPECT_EQ(domain.Value().Nodes().size(), 442U);
+    EXPECT_EQ(std::count_if(domain.Value().Warnings().begin(),
+                            domain.Value().Warnings().end(),
+                            [](const auto& warning) {
+                              return warning.code ==
+                                     "inactive-solid-rotation-boundary";
+                            }),
+              3);
+    auto model = fesa::AnalysisModel::Create(domain.Value());
+    auto dofs = fesa::DofManager::Create(model.Value());
+    ASSERT_TRUE(dofs.HasValue()) << name;
+    EXPECT_EQ(dofs.Value().FullDofCount(), 1326U);
+    EXPECT_EQ(dofs.Value().ConstrainedDofCount(), 51U);
+  }
+}
+
+class ConstantMatrixElement final : public fesa::Element {
+ public:
+  ConstantMatrixElement(const fesa::ElementDefinition& definition, double entry)
+      : layout_{definition.SourceId(),
+                definition.NodeIndices(),
+                {fesa::DofComponent::kUx, fesa::DofComponent::kUy,
+                 fesa::DofComponent::kUz}},
+        entry_{entry} {}
+  const fesa::ElementDofLayout& DofLayout() const noexcept override {
+    return layout_;
+  }
+  fesa::Result<fesa::ElementStiffnessContribution> ComputeStiffness()
+      const override {
+    fesa::Matrix values{24U, 24U};
+    for (std::size_t row = 0U; row < 24U; ++row)
+      for (std::size_t column = 0U; column < 24U; ++column)
+        values(row, column) = entry_;
+    return fesa::Result<fesa::ElementStiffnessContribution>::Success(
+        {layout_, std::move(values)});
+  }
+  fesa::Result<fesa::ElementResultBundle> Recover(
+      const fesa::Vector&) const override {
+    return fesa::Result<fesa::ElementResultBundle>::Failure(
+        fesa::Status::Failure(fesa::FailureCategory::kModel,
+                              {{fesa::Severity::kError,
+                                "test-no-recovery",
+                                {},
+                                "",
+                                "",
+                                "Assembly fixture has no recovery."}}));
+  }
+
+ private:
+  fesa::ElementDofLayout layout_;
+  double entry_;
+};
+TEST(Hex8Semantics, AssemblesFullSymmetricSolidMatricesInStableSourceOrder) {
+  const auto text =
+      Replace(Deck(), "99,10,20,30,40,50,60,70,80\n",
+              "99,10,20,30,40,50,60,70,80\n100,10,20,30,40,50,60,70,80\n"
+              "101,10,20,30,40,50,60,70,80\n");
+  auto domain = Map(text);
+  ASSERT_TRUE(domain.HasValue());
+  auto model = fesa::AnalysisModel::Create(domain.Value());
+  ConstantMatrixElement first{domain.Value().Elements()[0], 1e16};
+  ConstantMatrixElement second{domain.Value().Elements()[1], -1e16};
+  ConstantMatrixElement third{domain.Value().Elements()[2], 1};
+  const fesa::ElementView elements{std::cref(first), std::cref(second),
+                                   std::cref(third)};
+  fesa::DofManager dofs;
+  ASSERT_TRUE(dofs.Build(model.Value(), elements).IsOk());
+  auto serial = fesa::SparseAssembler::Assemble(elements, dofs,
+                                                fesa::SerialParallelFor{});
+  auto parallel =
+      fesa::SparseAssembler::Assemble(elements, dofs, fesa::TbbParallelFor{});
+  ASSERT_TRUE(serial.HasValue());
+  ASSERT_TRUE(parallel.HasValue());
+  EXPECT_EQ(serial.Value().Rows(), 24U);
+  EXPECT_EQ(serial.Value().Columns(), 24U);
+  EXPECT_EQ(serial.Value().Values().size(), 576U);
+  for (double value : serial.Value().Values()) EXPECT_EQ(value, 1.0);
+  EXPECT_EQ(serial.Value().RowOffsets(), parallel.Value().RowOffsets());
+  EXPECT_EQ(serial.Value().ColumnIndices(), parallel.Value().ColumnIndices());
+  EXPECT_EQ(serial.Value().Values(), parallel.Value().Values());
+}
+TEST(Hex8Semantics, ValidatesOutputNoOpsAndRejectsUnapprovedDynamicChildren) {
+  for (const std::string output :
+       {"*Output,field,variable=PRESELECT\n*Node Output\nU,RF\n*Element "
+        "Output,directions=YES\nS,E\n",
+        "*Output,history,variable=PRESELECT\n"})
+    EXPECT_TRUE(
+        Map(Replace(Deck(), "*End Step", output + "*End Step")).HasValue());
+  EXPECT_FALSE(Map(Replace(Deck(), "*End Step",
+                           "*Output,field,variable=OTHER\n*End Step"))
+                   .HasValue());
+  EXPECT_FALSE(
+      Map(Replace(
+              Deck(), "*End Step",
+              "*Output,field\n*Element Output,position=NODES\nS\n*End Step"))
+          .HasValue());
+  auto dynamic = Deck("*Dynamic,direct\n.1,1\n", "10,1,3\n", "*Density\n2\n");
+  EXPECT_FALSE(
+      Map(Replace(
+              dynamic, "*End Step",
+              "*Output,field,variable=PRESELECT\n*Node Output\nU\n*End Step"))
+          .HasValue());
+  EXPECT_FALSE(Map(Replace(dynamic, "*End Step",
+                           "*Restart,write,frequency=1\n*End Step"))
+                   .HasValue());
+}
+
+fesa::ModelDefinition SolidDefinition() {
+  fesa::ModelDefinition definition;
+  const std::array<std::array<double, 3>, 8> coordinates{{{0, 0, 0},
+                                                          {1, 0, 0},
+                                                          {1, 1, 0},
+                                                          {0, 1, 0},
+                                                          {0, 0, 1},
+                                                          {1, 0, 1},
+                                                          {1, 1, 1},
+                                                          {0, 1, 1}}};
+  for (std::size_t i = 0; i < coordinates.size(); ++i)
+    definition.nodes.push_back({{"I", static_cast<std::int64_t>(10 * (i + 1)),
+                                 std::to_string(10 * (i + 1))},
+                                coordinates[i],
+                                {"solid.inp", i + 1}});
+  definition.materials.emplace_back("M", 1000, .3,
+                                    fesa::SourceLocation{"solid.inp", 20});
+  definition.solid_sections.emplace_back(fesa::SourceEntityId{"P", 1, "E"}, "E",
+                                         0,
+                                         fesa::SourceLocation{"solid.inp", 21});
+  definition.solid_elements.emplace_back(
+      fesa::SourceEntityId{"I", 99, "99"},
+      std::array<fesa::EntityIndex, 8>{{0, 1, 2, 3, 4, 5, 6, 7}}, 0, 0,
+      fesa::SourceLocation{"solid.inp", 22});
+  definition.steps.emplace_back(
+      "Solid", std::vector<fesa::PrescribedDisplacementDefinition>{},
+      std::vector<fesa::NodalLoad>{}, 1., 1., 1., 1.,
+      fesa::SourceLocation{"solid.inp", 23});
+  return definition;
+}
+TEST(Hex8Semantics, RejectsInvalidProgrammaticSolidCandidates) {
+  EXPECT_TRUE(fesa::Domain::Create(SolidDefinition()).HasValue());
+  auto repeated = SolidDefinition();
+  repeated.solid_elements[0].node_indices[7] = 0;
+  EXPECT_FALSE(fesa::Domain::Create(std::move(repeated)).HasValue());
+  auto material = SolidDefinition();
+  material.materials[0].poisson_ratio = .5;
+  EXPECT_FALSE(fesa::Domain::Create(std::move(material)).HasValue());
+  auto section = SolidDefinition();
+  section.solid_elements[0].section_index = 99;
+  EXPECT_FALSE(fesa::Domain::Create(std::move(section)).HasValue());
+  auto rotational = SolidDefinition();
+  rotational.steps[0].loads.push_back({"10", 4, 0, {"solid.inp", 24}});
+  EXPECT_FALSE(fesa::Domain::Create(std::move(rotational)).HasValue());
+  auto unused = SolidDefinition();
+  unused.nodes.push_back({{"I", 90, "90"}, {2, 2, 2}, {"solid.inp", 25}});
+  EXPECT_FALSE(fesa::Domain::Create(std::move(unused)).HasValue());
+}
+
+TEST(Hex8Semantics, RejectsSecondProcedureBeforeReadingItsOptionsOrData) {
+  const std::array<std::string, 4> procedures{
+      "*Static\n1,1,1,1\n", "*Static,direct\n.1,1\n", "*Frequency\n2\n",
+      "*Dynamic,direct\n.1,1\n"};
+  for (const auto& first : procedures) {
+    ASSERT_TRUE(Map(Deck(first, "", "*Density\n2\n")).HasValue()) << first;
+    for (const auto& second : procedures) {
+      SCOPED_TRACE(first + second);
+      const auto result = Map(Deck(first + second, "", "*Density\n2\n"));
+      ASSERT_FALSE(result.HasValue());
+      ASSERT_FALSE(result.GetStatus().Diagnostics().empty());
+      EXPECT_EQ(result.GetStatus().Diagnostics()[0].code,
+                "unsupported-analysis-procedure");
+    }
+    const auto malformed =
+        Map(Deck(first + "*Static,direct,unapproved=YES\nnot-a-number\n", "",
+                 "*Density\n2\n"));
+    ASSERT_FALSE(malformed.HasValue());
+    ASSERT_FALSE(malformed.GetStatus().Diagnostics().empty());
+    EXPECT_EQ(malformed.GetStatus().Diagnostics()[0].code,
+              "unsupported-analysis-procedure");
+    EXPECT_EQ(malformed.GetStatus().Diagnostics()[0].keyword, "STATIC");
+  }
+}
+TEST(Hex8Semantics, AllowsOnlyApprovedStaticRestartNoOp) {
+  auto approved = Map(
+      Replace(Deck(), "*End Step", "*Restart,write,frequency=0\n*End Step"));
+  ASSERT_TRUE(approved.HasValue());
+  ASSERT_EQ(approved.Value().Warnings().size(), 1U);
+  EXPECT_EQ(approved.Value().Warnings()[0].keyword, "RESTART");
+  for (const std::string options :
+       {"read", "read,step=1,inc=1", "write", "write,frequency=1",
+        "write,frequency=0,endstep", "write,frequency=0,numberinterval=1",
+        "write=YES,frequency=0"}) {
+    SCOPED_TRACE(options);
+    auto result = Map(
+        Replace(Deck(), "*End Step", "*Restart," + options + "\n*End Step"));
+    ASSERT_FALSE(result.HasValue());
+    ASSERT_FALSE(result.GetStatus().Diagnostics().empty());
+    EXPECT_EQ(result.GetStatus().Diagnostics()[0].keyword, "RESTART");
+  }
+}
+TEST(Hex8Semantics,
+     PreservesShuffledSourceLabelsAndRejectsDuplicateIdentities) {
+  const auto deck = Replace(Deck(),
+                            "10,0,0,0\n20,1,0,0\n30,1,1,0\n40,0,1,0\n"
+                            "50,0,0,1\n60,1,0,1\n70,1,1,1\n80,0,1,1\n",
+                            "80,0,1,1\n20,1,0,0\n60,1,0,1\n40,0,1,0\n"
+                            "10,0,0,0\n70,1,1,1\n30,1,1,0\n50,0,0,1\n");
+  auto domain = Map(deck);
+  ASSERT_TRUE(domain.HasValue());
+  EXPECT_EQ(domain.Value().Nodes()[0].source_id.source_label, 80);
+  EXPECT_EQ(domain.Value().Nodes()[4].source_id.source_label, 10);
+  EXPECT_EQ(domain.Value().Elements()[0].NodeIndices(),
+            (std::vector<fesa::EntityIndex>{4, 1, 6, 3, 7, 2, 5, 0}));
+  auto model = fesa::AnalysisModel::Create(domain.Value());
+  ASSERT_TRUE(model.HasValue());
+  auto dofs = fesa::DofManager::Create(model.Value());
+  ASSERT_TRUE(dofs.HasValue());
+  EXPECT_EQ(dofs.Value().ConstrainedDofs(),
+            (std::vector<std::size_t>{12, 13, 14}));
+  EXPECT_FALSE(Map(Replace(deck, "20,1,0,0", "80,1,0,0")).HasValue());
+  EXPECT_FALSE(
+      Map(Replace(deck, "99,10,20,30,40,50,60,70,80",
+                  "99,10,20,30,40,50,60,70,80\n99,10,20,30,40,50,60,70,80"))
+          .HasValue());
+  auto shuffled = SolidDefinition();
+  std::swap(shuffled.nodes[0], shuffled.nodes[7]);
+  shuffled.solid_elements[0].node_indices = {7, 1, 2, 3, 4, 5, 6, 0};
+  auto direct = fesa::Domain::Create(std::move(shuffled));
+  ASSERT_TRUE(direct.HasValue());
+  EXPECT_EQ(direct.Value().Nodes()[0].source_id.source_label, 80);
+  EXPECT_EQ(direct.Value().Nodes()[7].source_id.source_label, 10);
+  EXPECT_EQ(direct.Value().SolidElements()[0].node_indices,
+            (std::array<fesa::EntityIndex, 8>{7, 1, 2, 3, 4, 5, 6, 0}));
+  auto nodes = SolidDefinition();
+  nodes.nodes[1].source_id = nodes.nodes[0].source_id;
+  EXPECT_FALSE(fesa::Domain::Create(std::move(nodes)).HasValue());
+  auto elements = SolidDefinition();
+  elements.solid_elements.push_back(elements.solid_elements[0]);
+  EXPECT_FALSE(fesa::Domain::Create(std::move(elements)).HasValue());
+}
+TEST(Hex8Semantics, RejectsUnknownSolidAssignmentTargets) {
+  for (const std::string assignment :
+       {"elset=Missing,material=M", "elset=E,material=Missing"}) {
+    SCOPED_TRACE(assignment);
+    const auto result = Map(Replace(Deck(), "elset=E,material=M", assignment));
+    ASSERT_FALSE(result.HasValue());
+    ASSERT_FALSE(result.GetStatus().Diagnostics().empty());
+    EXPECT_EQ(result.GetStatus().Diagnostics()[0].code,
+              "unresolved-solid-section");
+  }
+}
+TEST(Hex8Semantics, RejectsInvalidSolidDynamicSchedulesAndIncrementLimits) {
+  const auto valid = Deck("*Dynamic,direct\n.1,1\n", "", "*Density\n2\n");
+  ASSERT_TRUE(Map(valid).HasValue());
+  for (const std::string schedule : {".3,1", "0,1", "-1,1", ".1,0", "nan,1"}) {
+    SCOPED_TRACE(schedule);
+    EXPECT_FALSE(Map(Replace(valid, ".1,1\n", schedule + "\n")).HasValue());
+  }
+  for (const std::string limit : {"0", "9", "4294967296"}) {
+    SCOPED_TRACE(limit);
+    EXPECT_FALSE(Map(Replace(valid, "inc=100", "inc=" + limit)).HasValue());
+  }
+}
+}  // namespace