refactor: extract mitc4 material stiffness helpers

This commit is contained in:
NINI
2026-05-05 23:26:11 +09:00
parent 150653c3c7
commit 918e219c48
12 changed files with 715 additions and 498 deletions
+2
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@@ -2,6 +2,8 @@
#include "fesa/Element/MITC4Geometry.hpp"
#include "fesa/Element/MITC4Kinematics.hpp"
#include "fesa/Element/MITC4MaterialIntegration.hpp"
#include "fesa/Element/MITC4Stiffness.hpp"
#include "fesa/ModuleInfo.hpp"
namespace fesa::module {
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@@ -1,35 +1,16 @@
#pragma once
#include "fesa/Element/MITC4Geometry.hpp"
#include "fesa/Material/MITC4PlaneStressMaterial.hpp"
#include <array>
#include <cstddef>
#include <string>
#include <vector>
namespace fesa {
using MITC4ElementDofVector = std::array<Real, 24>;
using MITC4StrainVector = std::array<Real, 6>;
using MITC4StrainRow = std::array<Real, 24>;
using MITC4MaterialMatrix = std::array<std::array<Real, 6>, 6>;
enum class MITC4StrainComponent {
Eps11 = 0,
Eps22 = 1,
Eps33 = 2,
Gamma23 = 3,
Gamma13 = 4,
Gamma12 = 5
};
inline std::size_t strainComponentIndex(MITC4StrainComponent component) {
return static_cast<std::size_t>(component);
}
inline std::array<std::string, 6> mitc4StrainComponentLabels() {
return {"eps11", "eps22", "eps33", "gamma23", "gamma13", "gamma12"};
}
struct MITC4LocalRotations {
Real alpha = 0.0;
@@ -0,0 +1,182 @@
#pragma once
#include "fesa/Element/MITC4Kinematics.hpp"
#include "fesa/Material/MITC4PlaneStressMaterial.hpp"
#include <array>
#include <cmath>
#include <vector>
namespace fesa {
struct MITC4StrainTransform {
MITC4MaterialMatrix matrix{};
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
struct MITC4IntegrationPoint {
Real xi = 0.0;
Real eta = 0.0;
Real zeta = 0.0;
Real weight = 0.0;
};
struct MITC4MaterialIntegrationSample {
MITC4IntegrationPoint point;
MITC4IntegrationBasis basis;
MITC4StrainRows strain_rows;
MITC4MaterialMatrix local_material{};
MITC4MaterialMatrix strain_transform{};
MITC4MaterialMatrix convected_material{};
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
struct MITC4MaterialIntegrationData {
std::vector<MITC4MaterialIntegrationSample> samples;
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
inline std::array<MITC4IntegrationPoint, 8> mitc4GaussQuadrature2x2x2() {
const Real gauss = 1.0 / std::sqrt(3.0);
const std::array<Real, 2> points = {-gauss, gauss};
std::array<MITC4IntegrationPoint, 8> integration_points{};
std::size_t index = 0;
for (Real xi : points) {
for (Real eta : points) {
for (Real zeta : points) {
integration_points[index++] = {xi, eta, zeta, 1.0};
}
}
}
return integration_points;
}
inline std::array<std::array<Real, 3>, 3> mitc4TensorFromEngineeringComponent(std::size_t component) {
std::array<std::array<Real, 3>, 3> tensor{};
switch (static_cast<MITC4StrainComponent>(component)) {
case MITC4StrainComponent::Eps11:
tensor[0][0] = 1.0;
break;
case MITC4StrainComponent::Eps22:
tensor[1][1] = 1.0;
break;
case MITC4StrainComponent::Eps33:
tensor[2][2] = 1.0;
break;
case MITC4StrainComponent::Gamma23:
tensor[1][2] = 0.5;
tensor[2][1] = 0.5;
break;
case MITC4StrainComponent::Gamma13:
tensor[0][2] = 0.5;
tensor[2][0] = 0.5;
break;
case MITC4StrainComponent::Gamma12:
tensor[0][1] = 0.5;
tensor[1][0] = 0.5;
break;
}
return tensor;
}
inline MITC4StrainVector mitc4EngineeringVectorFromTensor(const std::array<std::array<Real, 3>, 3>& tensor) {
MITC4StrainVector vector{};
vector[strainComponentIndex(MITC4StrainComponent::Eps11)] = tensor[0][0];
vector[strainComponentIndex(MITC4StrainComponent::Eps22)] = tensor[1][1];
vector[strainComponentIndex(MITC4StrainComponent::Eps33)] = tensor[2][2];
vector[strainComponentIndex(MITC4StrainComponent::Gamma23)] = 2.0 * tensor[1][2];
vector[strainComponentIndex(MITC4StrainComponent::Gamma13)] = 2.0 * tensor[0][2];
vector[strainComponentIndex(MITC4StrainComponent::Gamma12)] = 2.0 * tensor[0][1];
return vector;
}
inline MITC4StrainTransform mitc4CovariantToLocalStrainTransform(const MITC4IntegrationBasis& basis,
Real tolerance = 1.0e-12) {
MITC4StrainTransform result;
result.diagnostics = basis.diagnostics;
const Real jacobian = dot(cross(basis.g1, basis.g2), basis.g3);
if (!isFinite(jacobian) || std::fabs(jacobian) <= tolerance) {
result.diagnostics.push_back(
mitc4Diagnostic("FESA-MITC4-SINGULAR-JACOBIAN", "MITC4 material transform Jacobian is near zero"));
return result;
}
if (hasError(result.diagnostics)) {
return result;
}
const std::array<Vec3, 3> contravariant = {
(1.0 / jacobian) * cross(basis.g2, basis.g3),
(1.0 / jacobian) * cross(basis.g3, basis.g1),
(1.0 / jacobian) * cross(basis.g1, basis.g2)};
const std::array<Vec3, 3> local = {basis.local.e1, basis.local.e2, basis.local.e3};
std::array<std::array<Real, 3>, 3> direction_cosines{};
for (std::size_t local_axis = 0; local_axis < 3; ++local_axis) {
for (std::size_t convected_axis = 0; convected_axis < 3; ++convected_axis) {
direction_cosines[local_axis][convected_axis] = dot(local[local_axis], contravariant[convected_axis]);
}
}
for (std::size_t column = 0; column < 6; ++column) {
const auto covariant_tensor = mitc4TensorFromEngineeringComponent(column);
std::array<std::array<Real, 3>, 3> local_tensor{};
for (std::size_t a = 0; a < 3; ++a) {
for (std::size_t b = 0; b < 3; ++b) {
for (std::size_t i = 0; i < 3; ++i) {
for (std::size_t j = 0; j < 3; ++j) {
local_tensor[a][b] += direction_cosines[a][i] * direction_cosines[b][j] * covariant_tensor[i][j];
}
}
}
}
const auto local_vector = mitc4EngineeringVectorFromTensor(local_tensor);
for (std::size_t row = 0; row < 6; ++row) {
result.matrix[row][column] = local_vector[row];
}
}
return result;
}
inline MITC4MaterialIntegrationData mitc4BuildMaterialIntegrationData(const MITC4Geometry& geometry,
Real elastic_modulus,
Real poisson_ratio,
Real shear_correction = 5.0 / 6.0) {
MITC4MaterialIntegrationData data;
const auto material = mitc4PlaneStressMaterialMatrix(elastic_modulus, poisson_ratio, shear_correction);
appendDiagnostics(data.diagnostics, material.diagnostics);
if (hasError(data.diagnostics)) {
return data;
}
for (const MITC4IntegrationPoint& point : mitc4GaussQuadrature2x2x2()) {
MITC4MaterialIntegrationSample sample;
sample.point = point;
sample.local_material = material.matrix;
sample.basis = computeMITC4IntegrationBasis(geometry, point.xi, point.eta, point.zeta);
appendDiagnostics(sample.diagnostics, sample.basis.diagnostics);
const auto transform = mitc4CovariantToLocalStrainTransform(sample.basis);
sample.strain_transform = transform.matrix;
appendDiagnostics(sample.diagnostics, transform.diagnostics);
sample.strain_rows = mitc4TiedCovariantStrainRows(geometry, point.xi, point.eta, point.zeta);
appendDiagnostics(sample.diagnostics, sample.strain_rows.diagnostics);
if (!hasError(sample.diagnostics)) {
sample.convected_material = mitc4TransformMaterialMatrix(sample.local_material, sample.strain_transform);
}
appendDiagnostics(data.diagnostics, sample.diagnostics);
data.samples.push_back(sample);
}
return data;
}
} // namespace fesa
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#pragma once
#include "fesa/Element/MITC4MaterialIntegration.hpp"
#include "fesa/Math/Math.hpp"
#include <algorithm>
#include <array>
#include <limits>
#include <stdexcept>
#include <vector>
namespace fesa {
struct ElementStiffnessOptions {
Real drilling_stiffness_scale = 1.0e-3;
};
struct MITC4DrillingStabilizationResult {
DenseMatrix local_with_drilling;
Real reference_diagonal = 0.0;
Real drilling_stiffness = 0.0;
Real drilling_stiffness_scale = 0.0;
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
struct MITC4ElementStiffnessResult {
DenseMatrix local_without_drilling;
DenseMatrix local_with_drilling;
DenseMatrix global;
std::size_t integration_point_count = 0;
Real drilling_reference_diagonal = 0.0;
Real drilling_stiffness = 0.0;
Real drilling_stiffness_scale = 0.0;
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
inline DenseMatrix mitc4LocalDofTransform(const MITC4Geometry& geometry) {
DenseMatrix transform(24, 24);
for (LocalIndex node = 0; node < 4; ++node) {
const LocalIndex base = 6 * node;
const auto& frame = geometry.nodal_frames[static_cast<std::size_t>(node)];
const std::array<Vec3, 3> axes = {frame.v1, frame.v2, frame.vn};
for (LocalIndex local_axis = 0; local_axis < 3; ++local_axis) {
const Vec3 axis = axes[static_cast<std::size_t>(local_axis)];
transform(base + local_axis, base + 0) = axis.x;
transform(base + local_axis, base + 1) = axis.y;
transform(base + local_axis, base + 2) = axis.z;
transform(base + 3 + local_axis, base + 3) = axis.x;
transform(base + 3 + local_axis, base + 4) = axis.y;
transform(base + 3 + local_axis, base + 5) = axis.z;
}
}
return transform;
}
inline MITC4StrainRows mitc4TransformStrainRowsToLocalDofs(const MITC4StrainRows& global_rows,
const DenseMatrix& local_dof_transform) {
MITC4StrainRows local_rows;
local_rows.diagnostics = global_rows.diagnostics;
if (hasError(local_rows.diagnostics)) {
return local_rows;
}
for (std::size_t component = 0; component < 6; ++component) {
for (LocalIndex local_dof = 0; local_dof < 24; ++local_dof) {
Real value = 0.0;
for (LocalIndex global_dof = 0; global_dof < 24; ++global_dof) {
value += global_rows.rows[component][static_cast<std::size_t>(global_dof)] *
local_dof_transform(local_dof, global_dof);
}
local_rows.rows[component][static_cast<std::size_t>(local_dof)] = value;
}
}
return local_rows;
}
inline void accumulateMITC4BtDB(DenseMatrix& stiffness, const MITC4StrainRows& rows,
const MITC4MaterialMatrix& material, Real factor) {
for (LocalIndex i = 0; i < 24; ++i) {
for (LocalIndex j = 0; j < 24; ++j) {
Real value = 0.0;
for (std::size_t a = 0; a < 6; ++a) {
for (std::size_t b = 0; b < 6; ++b) {
value += rows.rows[a][static_cast<std::size_t>(i)] * material[a][b] *
rows.rows[b][static_cast<std::size_t>(j)];
}
}
stiffness.add(i, j, value * factor);
}
}
}
inline Real mitc4MinimumPositivePhysicalLocalDiagonal(const DenseMatrix& local_without_drilling,
Real tolerance = 1.0e-12) {
Real minimum = std::numeric_limits<Real>::infinity();
for (LocalIndex node = 0; node < 4; ++node) {
for (LocalIndex local_dof = 0; local_dof < 5; ++local_dof) {
const Real diagonal = local_without_drilling(6 * node + local_dof, 6 * node + local_dof);
if (isFinite(diagonal) && diagonal > tolerance) {
minimum = std::min(minimum, diagonal);
}
}
}
return minimum;
}
inline MITC4DrillingStabilizationResult mitc4ApplyDrillingStabilization(const DenseMatrix& local_without_drilling,
Real drilling_stiffness_scale,
Real tolerance = 1.0e-12) {
MITC4DrillingStabilizationResult result;
result.local_with_drilling = local_without_drilling;
result.drilling_stiffness_scale = drilling_stiffness_scale;
if (!isFinite(drilling_stiffness_scale) || drilling_stiffness_scale < 0.0) {
result.diagnostics.push_back(
mitc4Diagnostic("FESA-MITC4-DRILLING-SCALE", "MITC4 drilling stiffness scale must be non-negative and finite"));
return result;
}
result.reference_diagonal = mitc4MinimumPositivePhysicalLocalDiagonal(local_without_drilling, tolerance);
if (!isFinite(result.reference_diagonal)) {
result.diagnostics.push_back(mitc4Diagnostic("FESA-MITC4-DRILLING-REFERENCE",
"MITC4 drilling stiffness reference diagonal is not positive"));
return result;
}
result.drilling_stiffness = drilling_stiffness_scale * result.reference_diagonal;
for (LocalIndex node = 0; node < 4; ++node) {
const LocalIndex gamma = 6 * node + 5;
result.local_with_drilling.add(gamma, gamma, result.drilling_stiffness);
}
return result;
}
inline DenseMatrix mitc4TransformLocalStiffnessToGlobal(const DenseMatrix& local_stiffness,
const DenseMatrix& local_dof_transform) {
DenseMatrix global(24, 24);
for (LocalIndex i = 0; i < 24; ++i) {
for (LocalIndex j = 0; j < 24; ++j) {
Real value = 0.0;
for (LocalIndex a = 0; a < 24; ++a) {
for (LocalIndex b = 0; b < 24; ++b) {
value += local_dof_transform(a, i) * local_stiffness(a, b) * local_dof_transform(b, j);
}
}
global(i, j) = value;
}
}
return global;
}
inline MITC4ElementStiffnessResult mitc4ElementStiffness(const std::array<Vec3, 4>& coordinates,
Real elastic_modulus, Real poisson_ratio, Real thickness,
ElementStiffnessOptions options = {}) {
MITC4ElementStiffnessResult result;
result.local_without_drilling = DenseMatrix(24, 24);
result.local_with_drilling = DenseMatrix(24, 24);
result.global = DenseMatrix(24, 24);
result.drilling_stiffness_scale = options.drilling_stiffness_scale;
const MITC4Geometry geometry = buildMITC4Geometry(coordinates, thickness);
appendDiagnostics(result.diagnostics, geometry.diagnostics);
if (hasError(result.diagnostics)) {
return result;
}
const MITC4MaterialIntegrationData integration =
mitc4BuildMaterialIntegrationData(geometry, elastic_modulus, poisson_ratio);
appendDiagnostics(result.diagnostics, integration.diagnostics);
if (hasError(result.diagnostics)) {
return result;
}
result.integration_point_count = integration.samples.size();
const DenseMatrix local_dof_transform = mitc4LocalDofTransform(geometry);
for (const MITC4MaterialIntegrationSample& sample : integration.samples) {
const MITC4StrainRows local_rows =
mitc4TransformStrainRowsToLocalDofs(sample.strain_rows, local_dof_transform);
appendDiagnostics(result.diagnostics, local_rows.diagnostics);
if (hasError(result.diagnostics)) {
return result;
}
const Real factor = std::fabs(sample.basis.jacobian) * sample.point.weight;
accumulateMITC4BtDB(result.local_without_drilling, local_rows, sample.convected_material, factor);
}
const auto drilling = mitc4ApplyDrillingStabilization(result.local_without_drilling, options.drilling_stiffness_scale);
appendDiagnostics(result.diagnostics, drilling.diagnostics);
result.local_with_drilling = drilling.local_with_drilling;
result.drilling_reference_diagonal = drilling.reference_diagonal;
result.drilling_stiffness = drilling.drilling_stiffness;
result.drilling_stiffness_scale = drilling.drilling_stiffness_scale;
if (hasError(result.diagnostics)) {
return result;
}
result.global = mitc4TransformLocalStiffnessToGlobal(result.local_with_drilling, local_dof_transform);
return result;
}
inline std::vector<Real> mitc4ElementInternalForce(const MITC4ElementStiffnessResult& stiffness,
const std::vector<Real>& element_displacement) {
if (stiffness.global.rows() != static_cast<LocalIndex>(element_displacement.size())) {
throw std::runtime_error("MITC4 internal force size mismatch");
}
return stiffness.global.multiply(element_displacement);
}
class MITC4ElementKernel {
public:
DenseMatrix stiffness(const std::array<Vec3, 4>& coordinates, Real elastic_modulus, Real poisson_ratio, Real thickness,
ElementStiffnessOptions options = {}) const {
const auto result = mitc4ElementStiffness(coordinates, elastic_modulus, poisson_ratio, thickness, options);
if (!result.ok()) {
throw std::runtime_error(result.diagnostics.empty() ? "invalid MITC4 stiffness"
: result.diagnostics.front().message);
}
return result.global;
}
};
} // namespace fesa
@@ -0,0 +1,121 @@
#pragma once
#include "fesa/Math/Vector.hpp"
#include "fesa/Util/Diagnostics.hpp"
#include <array>
#include <cstddef>
#include <string>
#include <utility>
#include <vector>
namespace fesa {
using MITC4StrainVector = std::array<Real, 6>;
using MITC4MaterialMatrix = std::array<std::array<Real, 6>, 6>;
enum class MITC4StrainComponent {
Eps11 = 0,
Eps22 = 1,
Eps33 = 2,
Gamma23 = 3,
Gamma13 = 4,
Gamma12 = 5
};
inline std::size_t strainComponentIndex(MITC4StrainComponent component) {
return static_cast<std::size_t>(component);
}
inline std::array<std::string, 6> mitc4StrainComponentLabels() {
return {"eps11", "eps22", "eps33", "gamma23", "gamma13", "gamma12"};
}
struct MITC4MaterialMatrixEvaluation {
MITC4MaterialMatrix matrix{};
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
inline Diagnostic mitc4MaterialDiagnostic(std::string code, std::string message) {
return makeDiagnostic(Severity::Error, std::move(code), std::move(message), "mitc4", "<element>", 0);
}
inline MITC4MaterialMatrixEvaluation mitc4PlaneStressMaterialMatrix(Real elastic_modulus, Real poisson_ratio,
Real shear_correction = 5.0 / 6.0,
Real tolerance = 1.0e-12) {
MITC4MaterialMatrixEvaluation result;
if (!isFinite(elastic_modulus) || elastic_modulus <= tolerance) {
result.diagnostics.push_back(
mitc4MaterialDiagnostic("FESA-MITC4-MATERIAL", "MITC4 elastic modulus must be positive and finite"));
}
if (!isFinite(poisson_ratio) || poisson_ratio <= -1.0 || poisson_ratio >= 0.5) {
result.diagnostics.push_back(
mitc4MaterialDiagnostic("FESA-MITC4-POISSON", "MITC4 isotropic Poisson ratio must satisfy -1 < nu < 0.5"));
}
if (!isFinite(shear_correction) || shear_correction <= tolerance) {
result.diagnostics.push_back(mitc4MaterialDiagnostic("FESA-MITC4-SHEAR-CORRECTION",
"MITC4 shear correction factor must be positive and finite"));
}
if (hasError(result.diagnostics)) {
return result;
}
const Real scale = elastic_modulus / (1.0 - poisson_ratio * poisson_ratio);
const Real shear_modulus = elastic_modulus / (2.0 * (1.0 + poisson_ratio));
const std::size_t eps11 = strainComponentIndex(MITC4StrainComponent::Eps11);
const std::size_t eps22 = strainComponentIndex(MITC4StrainComponent::Eps22);
const std::size_t gamma23 = strainComponentIndex(MITC4StrainComponent::Gamma23);
const std::size_t gamma13 = strainComponentIndex(MITC4StrainComponent::Gamma13);
const std::size_t gamma12 = strainComponentIndex(MITC4StrainComponent::Gamma12);
result.matrix[eps11][eps11] = scale;
result.matrix[eps11][eps22] = poisson_ratio * scale;
result.matrix[eps22][eps11] = poisson_ratio * scale;
result.matrix[eps22][eps22] = scale;
result.matrix[gamma23][gamma23] = shear_correction * shear_modulus;
result.matrix[gamma13][gamma13] = shear_correction * shear_modulus;
result.matrix[gamma12][gamma12] = shear_modulus;
return result;
}
inline MITC4StrainVector multiplyMITC4MaterialMatrix(const MITC4MaterialMatrix& matrix,
const MITC4StrainVector& vector) {
MITC4StrainVector result{};
for (std::size_t row = 0; row < 6; ++row) {
for (std::size_t col = 0; col < 6; ++col) {
result[row] += matrix[row][col] * vector[col];
}
}
return result;
}
inline Real dotMITC4Vector(const MITC4StrainVector& a, const MITC4StrainVector& b) {
Real result = 0.0;
for (std::size_t i = 0; i < 6; ++i) {
result += a[i] * b[i];
}
return result;
}
inline MITC4MaterialMatrix mitc4TransformMaterialMatrix(const MITC4MaterialMatrix& local_material,
const MITC4MaterialMatrix& covariant_to_local) {
MITC4MaterialMatrix result{};
for (std::size_t i = 0; i < 6; ++i) {
for (std::size_t j = 0; j < 6; ++j) {
Real value = 0.0;
for (std::size_t a = 0; a < 6; ++a) {
for (std::size_t b = 0; b < 6; ++b) {
value += covariant_to_local[a][i] * local_material[a][b] * covariant_to_local[b][j];
}
}
result[i][j] = value;
}
}
return result;
}
} // namespace fesa
+1
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@@ -1,5 +1,6 @@
#pragma once
#include "fesa/Material/MITC4PlaneStressMaterial.hpp"
#include "fesa/ModuleInfo.hpp"
namespace fesa::module {
+14 -472
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@@ -5,6 +5,7 @@
#include "fesa/Element/Element.hpp"
#include "fesa/IO/IO.hpp"
#include "fesa/Load/Load.hpp"
#include "fesa/Material/Material.hpp"
#include "fesa/Math/Math.hpp"
#include "fesa/ModuleInfo.hpp"
#include "fesa/Property/Property.hpp"
@@ -57,7 +58,9 @@ inline SparsePattern buildReducedSparsePattern(const Domain& domain, const DofMa
return pattern;
}
inline std::vector<Real> recoverFullReaction(const DenseMatrix& k_full, const std::vector<Real>& u_full, const std::vector<Real>& f_full) {
inline std::vector<Real> recoverFullReaction(const DenseMatrix& k_full,
const std::vector<Real>& u_full,
const std::vector<Real>& f_full) {
if (k_full.rows() != k_full.cols() || static_cast<LocalIndex>(u_full.size()) != k_full.cols() ||
static_cast<LocalIndex>(f_full.size()) != k_full.rows()) {
throw std::runtime_error("full reaction size mismatch");
@@ -69,471 +72,6 @@ inline std::vector<Real> recoverFullReaction(const DenseMatrix& k_full, const st
return reaction;
}
struct MITC4MaterialMatrixEvaluation {
MITC4MaterialMatrix matrix{};
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
struct MITC4StrainTransform {
MITC4MaterialMatrix matrix{};
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
struct MITC4IntegrationPoint {
Real xi = 0.0;
Real eta = 0.0;
Real zeta = 0.0;
Real weight = 0.0;
};
struct MITC4MaterialIntegrationSample {
MITC4IntegrationPoint point;
MITC4IntegrationBasis basis;
MITC4StrainRows strain_rows;
MITC4MaterialMatrix local_material{};
MITC4MaterialMatrix strain_transform{};
MITC4MaterialMatrix convected_material{};
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
struct MITC4MaterialIntegrationData {
std::vector<MITC4MaterialIntegrationSample> samples;
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
inline std::array<MITC4IntegrationPoint, 8> mitc4GaussQuadrature2x2x2() {
const Real gauss = 1.0 / std::sqrt(3.0);
const std::array<Real, 2> points = {-gauss, gauss};
std::array<MITC4IntegrationPoint, 8> integration_points{};
std::size_t index = 0;
for (Real xi : points) {
for (Real eta : points) {
for (Real zeta : points) {
integration_points[index++] = {xi, eta, zeta, 1.0};
}
}
}
return integration_points;
}
inline MITC4MaterialMatrixEvaluation mitc4PlaneStressMaterialMatrix(Real elastic_modulus, Real poisson_ratio,
Real shear_correction = 5.0 / 6.0,
Real tolerance = 1.0e-12) {
MITC4MaterialMatrixEvaluation result;
if (!isFinite(elastic_modulus) || elastic_modulus <= tolerance) {
result.diagnostics.push_back(
mitc4Diagnostic("FESA-MITC4-MATERIAL", "MITC4 elastic modulus must be positive and finite"));
}
if (!isFinite(poisson_ratio) || poisson_ratio <= -1.0 || poisson_ratio >= 0.5) {
result.diagnostics.push_back(
mitc4Diagnostic("FESA-MITC4-POISSON", "MITC4 isotropic Poisson ratio must satisfy -1 < nu < 0.5"));
}
if (!isFinite(shear_correction) || shear_correction <= tolerance) {
result.diagnostics.push_back(
mitc4Diagnostic("FESA-MITC4-SHEAR-CORRECTION", "MITC4 shear correction factor must be positive and finite"));
}
if (hasError(result.diagnostics)) {
return result;
}
const Real scale = elastic_modulus / (1.0 - poisson_ratio * poisson_ratio);
const Real shear_modulus = elastic_modulus / (2.0 * (1.0 + poisson_ratio));
const std::size_t eps11 = strainComponentIndex(MITC4StrainComponent::Eps11);
const std::size_t eps22 = strainComponentIndex(MITC4StrainComponent::Eps22);
const std::size_t gamma23 = strainComponentIndex(MITC4StrainComponent::Gamma23);
const std::size_t gamma13 = strainComponentIndex(MITC4StrainComponent::Gamma13);
const std::size_t gamma12 = strainComponentIndex(MITC4StrainComponent::Gamma12);
result.matrix[eps11][eps11] = scale;
result.matrix[eps11][eps22] = poisson_ratio * scale;
result.matrix[eps22][eps11] = poisson_ratio * scale;
result.matrix[eps22][eps22] = scale;
result.matrix[gamma23][gamma23] = shear_correction * shear_modulus;
result.matrix[gamma13][gamma13] = shear_correction * shear_modulus;
result.matrix[gamma12][gamma12] = shear_modulus;
return result;
}
inline MITC4StrainVector multiplyMITC4MaterialMatrix(const MITC4MaterialMatrix& matrix, const MITC4StrainVector& vector) {
MITC4StrainVector result{};
for (std::size_t row = 0; row < 6; ++row) {
for (std::size_t col = 0; col < 6; ++col) {
result[row] += matrix[row][col] * vector[col];
}
}
return result;
}
inline Real dotMITC4Vector(const MITC4StrainVector& a, const MITC4StrainVector& b) {
Real result = 0.0;
for (std::size_t i = 0; i < 6; ++i) {
result += a[i] * b[i];
}
return result;
}
inline MITC4MaterialMatrix mitc4TransformMaterialMatrix(const MITC4MaterialMatrix& local_material,
const MITC4MaterialMatrix& covariant_to_local) {
MITC4MaterialMatrix result{};
for (std::size_t i = 0; i < 6; ++i) {
for (std::size_t j = 0; j < 6; ++j) {
Real value = 0.0;
for (std::size_t a = 0; a < 6; ++a) {
for (std::size_t b = 0; b < 6; ++b) {
value += covariant_to_local[a][i] * local_material[a][b] * covariant_to_local[b][j];
}
}
result[i][j] = value;
}
}
return result;
}
inline std::array<std::array<Real, 3>, 3> mitc4TensorFromEngineeringComponent(std::size_t component) {
std::array<std::array<Real, 3>, 3> tensor{};
switch (static_cast<MITC4StrainComponent>(component)) {
case MITC4StrainComponent::Eps11:
tensor[0][0] = 1.0;
break;
case MITC4StrainComponent::Eps22:
tensor[1][1] = 1.0;
break;
case MITC4StrainComponent::Eps33:
tensor[2][2] = 1.0;
break;
case MITC4StrainComponent::Gamma23:
tensor[1][2] = 0.5;
tensor[2][1] = 0.5;
break;
case MITC4StrainComponent::Gamma13:
tensor[0][2] = 0.5;
tensor[2][0] = 0.5;
break;
case MITC4StrainComponent::Gamma12:
tensor[0][1] = 0.5;
tensor[1][0] = 0.5;
break;
}
return tensor;
}
inline MITC4StrainVector mitc4EngineeringVectorFromTensor(const std::array<std::array<Real, 3>, 3>& tensor) {
MITC4StrainVector vector{};
vector[strainComponentIndex(MITC4StrainComponent::Eps11)] = tensor[0][0];
vector[strainComponentIndex(MITC4StrainComponent::Eps22)] = tensor[1][1];
vector[strainComponentIndex(MITC4StrainComponent::Eps33)] = tensor[2][2];
vector[strainComponentIndex(MITC4StrainComponent::Gamma23)] = 2.0 * tensor[1][2];
vector[strainComponentIndex(MITC4StrainComponent::Gamma13)] = 2.0 * tensor[0][2];
vector[strainComponentIndex(MITC4StrainComponent::Gamma12)] = 2.0 * tensor[0][1];
return vector;
}
inline MITC4StrainTransform mitc4CovariantToLocalStrainTransform(const MITC4IntegrationBasis& basis,
Real tolerance = 1.0e-12) {
MITC4StrainTransform result;
result.diagnostics = basis.diagnostics;
const Real jacobian = dot(cross(basis.g1, basis.g2), basis.g3);
if (!isFinite(jacobian) || std::fabs(jacobian) <= tolerance) {
result.diagnostics.push_back(
mitc4Diagnostic("FESA-MITC4-SINGULAR-JACOBIAN", "MITC4 material transform Jacobian is near zero"));
return result;
}
if (hasError(result.diagnostics)) {
return result;
}
const std::array<Vec3, 3> contravariant = {
(1.0 / jacobian) * cross(basis.g2, basis.g3),
(1.0 / jacobian) * cross(basis.g3, basis.g1),
(1.0 / jacobian) * cross(basis.g1, basis.g2)};
const std::array<Vec3, 3> local = {basis.local.e1, basis.local.e2, basis.local.e3};
std::array<std::array<Real, 3>, 3> direction_cosines{};
for (std::size_t local_axis = 0; local_axis < 3; ++local_axis) {
for (std::size_t convected_axis = 0; convected_axis < 3; ++convected_axis) {
direction_cosines[local_axis][convected_axis] = dot(local[local_axis], contravariant[convected_axis]);
}
}
for (std::size_t column = 0; column < 6; ++column) {
const auto covariant_tensor = mitc4TensorFromEngineeringComponent(column);
std::array<std::array<Real, 3>, 3> local_tensor{};
for (std::size_t a = 0; a < 3; ++a) {
for (std::size_t b = 0; b < 3; ++b) {
for (std::size_t i = 0; i < 3; ++i) {
for (std::size_t j = 0; j < 3; ++j) {
local_tensor[a][b] += direction_cosines[a][i] * direction_cosines[b][j] * covariant_tensor[i][j];
}
}
}
}
const auto local_vector = mitc4EngineeringVectorFromTensor(local_tensor);
for (std::size_t row = 0; row < 6; ++row) {
result.matrix[row][column] = local_vector[row];
}
}
return result;
}
inline MITC4MaterialIntegrationData mitc4BuildMaterialIntegrationData(const MITC4Geometry& geometry, Real elastic_modulus,
Real poisson_ratio,
Real shear_correction = 5.0 / 6.0) {
MITC4MaterialIntegrationData data;
const auto material = mitc4PlaneStressMaterialMatrix(elastic_modulus, poisson_ratio, shear_correction);
appendDiagnostics(data.diagnostics, material.diagnostics);
if (hasError(data.diagnostics)) {
return data;
}
for (const MITC4IntegrationPoint& point : mitc4GaussQuadrature2x2x2()) {
MITC4MaterialIntegrationSample sample;
sample.point = point;
sample.local_material = material.matrix;
sample.basis = computeMITC4IntegrationBasis(geometry, point.xi, point.eta, point.zeta);
appendDiagnostics(sample.diagnostics, sample.basis.diagnostics);
const auto transform = mitc4CovariantToLocalStrainTransform(sample.basis);
sample.strain_transform = transform.matrix;
appendDiagnostics(sample.diagnostics, transform.diagnostics);
sample.strain_rows = mitc4TiedCovariantStrainRows(geometry, point.xi, point.eta, point.zeta);
appendDiagnostics(sample.diagnostics, sample.strain_rows.diagnostics);
if (!hasError(sample.diagnostics)) {
sample.convected_material = mitc4TransformMaterialMatrix(sample.local_material, sample.strain_transform);
}
appendDiagnostics(data.diagnostics, sample.diagnostics);
data.samples.push_back(sample);
}
return data;
}
struct ElementStiffnessOptions {
Real drilling_stiffness_scale = 1.0e-3;
};
struct MITC4DrillingStabilizationResult {
DenseMatrix local_with_drilling;
Real reference_diagonal = 0.0;
Real drilling_stiffness = 0.0;
Real drilling_stiffness_scale = 0.0;
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
struct MITC4ElementStiffnessResult {
DenseMatrix local_without_drilling;
DenseMatrix local_with_drilling;
DenseMatrix global;
std::size_t integration_point_count = 0;
Real drilling_reference_diagonal = 0.0;
Real drilling_stiffness = 0.0;
Real drilling_stiffness_scale = 0.0;
std::vector<Diagnostic> diagnostics;
bool ok() const {
return !hasError(diagnostics);
}
};
inline DenseMatrix mitc4LocalDofTransform(const MITC4Geometry& geometry) {
DenseMatrix transform(24, 24);
for (LocalIndex node = 0; node < 4; ++node) {
const LocalIndex base = 6 * node;
const auto& frame = geometry.nodal_frames[static_cast<std::size_t>(node)];
const std::array<Vec3, 3> axes = {frame.v1, frame.v2, frame.vn};
for (LocalIndex local_axis = 0; local_axis < 3; ++local_axis) {
const Vec3 axis = axes[static_cast<std::size_t>(local_axis)];
transform(base + local_axis, base + 0) = axis.x;
transform(base + local_axis, base + 1) = axis.y;
transform(base + local_axis, base + 2) = axis.z;
transform(base + 3 + local_axis, base + 3) = axis.x;
transform(base + 3 + local_axis, base + 4) = axis.y;
transform(base + 3 + local_axis, base + 5) = axis.z;
}
}
return transform;
}
inline MITC4StrainRows mitc4TransformStrainRowsToLocalDofs(const MITC4StrainRows& global_rows,
const DenseMatrix& local_dof_transform) {
MITC4StrainRows local_rows;
local_rows.diagnostics = global_rows.diagnostics;
if (hasError(local_rows.diagnostics)) {
return local_rows;
}
for (std::size_t component = 0; component < 6; ++component) {
for (LocalIndex local_dof = 0; local_dof < 24; ++local_dof) {
Real value = 0.0;
for (LocalIndex global_dof = 0; global_dof < 24; ++global_dof) {
value += global_rows.rows[component][static_cast<std::size_t>(global_dof)] *
local_dof_transform(local_dof, global_dof);
}
local_rows.rows[component][static_cast<std::size_t>(local_dof)] = value;
}
}
return local_rows;
}
inline void accumulateMITC4BtDB(DenseMatrix& stiffness, const MITC4StrainRows& rows,
const MITC4MaterialMatrix& material, Real factor) {
for (LocalIndex i = 0; i < 24; ++i) {
for (LocalIndex j = 0; j < 24; ++j) {
Real value = 0.0;
for (std::size_t a = 0; a < 6; ++a) {
for (std::size_t b = 0; b < 6; ++b) {
value += rows.rows[a][static_cast<std::size_t>(i)] * material[a][b] *
rows.rows[b][static_cast<std::size_t>(j)];
}
}
stiffness.add(i, j, value * factor);
}
}
}
inline Real mitc4MinimumPositivePhysicalLocalDiagonal(const DenseMatrix& local_without_drilling,
Real tolerance = 1.0e-12) {
Real minimum = std::numeric_limits<Real>::infinity();
for (LocalIndex node = 0; node < 4; ++node) {
for (LocalIndex local_dof = 0; local_dof < 5; ++local_dof) {
const Real diagonal = local_without_drilling(6 * node + local_dof, 6 * node + local_dof);
if (isFinite(diagonal) && diagonal > tolerance) {
minimum = std::min(minimum, diagonal);
}
}
}
return minimum;
}
inline MITC4DrillingStabilizationResult mitc4ApplyDrillingStabilization(const DenseMatrix& local_without_drilling,
Real drilling_stiffness_scale,
Real tolerance = 1.0e-12) {
MITC4DrillingStabilizationResult result;
result.local_with_drilling = local_without_drilling;
result.drilling_stiffness_scale = drilling_stiffness_scale;
if (!isFinite(drilling_stiffness_scale) || drilling_stiffness_scale < 0.0) {
result.diagnostics.push_back(
mitc4Diagnostic("FESA-MITC4-DRILLING-SCALE", "MITC4 drilling stiffness scale must be non-negative and finite"));
return result;
}
result.reference_diagonal = mitc4MinimumPositivePhysicalLocalDiagonal(local_without_drilling, tolerance);
if (!isFinite(result.reference_diagonal)) {
result.diagnostics.push_back(mitc4Diagnostic("FESA-MITC4-DRILLING-REFERENCE",
"MITC4 drilling stiffness reference diagonal is not positive"));
return result;
}
result.drilling_stiffness = drilling_stiffness_scale * result.reference_diagonal;
for (LocalIndex node = 0; node < 4; ++node) {
const LocalIndex gamma = 6 * node + 5;
result.local_with_drilling.add(gamma, gamma, result.drilling_stiffness);
}
return result;
}
inline DenseMatrix mitc4TransformLocalStiffnessToGlobal(const DenseMatrix& local_stiffness,
const DenseMatrix& local_dof_transform) {
DenseMatrix global(24, 24);
for (LocalIndex i = 0; i < 24; ++i) {
for (LocalIndex j = 0; j < 24; ++j) {
Real value = 0.0;
for (LocalIndex a = 0; a < 24; ++a) {
for (LocalIndex b = 0; b < 24; ++b) {
value += local_dof_transform(a, i) * local_stiffness(a, b) * local_dof_transform(b, j);
}
}
global(i, j) = value;
}
}
return global;
}
inline MITC4ElementStiffnessResult mitc4ElementStiffness(const std::array<Vec3, 4>& coordinates,
Real elastic_modulus, Real poisson_ratio, Real thickness,
ElementStiffnessOptions options = {}) {
MITC4ElementStiffnessResult result;
result.local_without_drilling = DenseMatrix(24, 24);
result.local_with_drilling = DenseMatrix(24, 24);
result.global = DenseMatrix(24, 24);
result.drilling_stiffness_scale = options.drilling_stiffness_scale;
const MITC4Geometry geometry = buildMITC4Geometry(coordinates, thickness);
appendDiagnostics(result.diagnostics, geometry.diagnostics);
if (hasError(result.diagnostics)) {
return result;
}
const MITC4MaterialIntegrationData integration =
mitc4BuildMaterialIntegrationData(geometry, elastic_modulus, poisson_ratio);
appendDiagnostics(result.diagnostics, integration.diagnostics);
if (hasError(result.diagnostics)) {
return result;
}
result.integration_point_count = integration.samples.size();
const DenseMatrix local_dof_transform = mitc4LocalDofTransform(geometry);
for (const MITC4MaterialIntegrationSample& sample : integration.samples) {
const MITC4StrainRows local_rows =
mitc4TransformStrainRowsToLocalDofs(sample.strain_rows, local_dof_transform);
appendDiagnostics(result.diagnostics, local_rows.diagnostics);
if (hasError(result.diagnostics)) {
return result;
}
const Real factor = std::fabs(sample.basis.jacobian) * sample.point.weight;
accumulateMITC4BtDB(result.local_without_drilling, local_rows, sample.convected_material, factor);
}
const auto drilling = mitc4ApplyDrillingStabilization(result.local_without_drilling, options.drilling_stiffness_scale);
appendDiagnostics(result.diagnostics, drilling.diagnostics);
result.local_with_drilling = drilling.local_with_drilling;
result.drilling_reference_diagonal = drilling.reference_diagonal;
result.drilling_stiffness = drilling.drilling_stiffness;
result.drilling_stiffness_scale = drilling.drilling_stiffness_scale;
if (hasError(result.diagnostics)) {
return result;
}
result.global = mitc4TransformLocalStiffnessToGlobal(result.local_with_drilling, local_dof_transform);
return result;
}
inline std::vector<Real> mitc4ElementInternalForce(const MITC4ElementStiffnessResult& stiffness,
const std::vector<Real>& element_displacement) {
if (stiffness.global.rows() != static_cast<LocalIndex>(element_displacement.size())) {
throw std::runtime_error("MITC4 internal force size mismatch");
}
return stiffness.global.multiply(element_displacement);
}
class MITC4ElementKernel {
public:
DenseMatrix stiffness(const std::array<Vec3, 4>& coordinates, Real elastic_modulus, Real poisson_ratio, Real thickness,
ElementStiffnessOptions options = {}) const {
const auto result = mitc4ElementStiffness(coordinates, elastic_modulus, poisson_ratio, thickness, options);
if (!result.ok()) {
throw std::runtime_error(result.diagnostics.empty() ? "invalid MITC4 stiffness"
: result.diagnostics.front().message);
}
return result.global;
}
};
struct AssemblyResult {
DenseMatrix k_full;
std::vector<Real> f_full;
@@ -568,12 +106,14 @@ inline AssemblyResult assembleSystem(const Domain& domain, const DofManager& dof
for (const auto& [element_id, element] : domain.elements) {
const ShellSection* section = shellSectionForElement(domain, element_id);
if (section == nullptr) {
result.diagnostics.push_back({Severity::Error, "FESA-ASSEMBLY-MISSING-PROPERTY", "Element has no shell section", {}});
result.diagnostics.push_back(
{Severity::Error, "FESA-ASSEMBLY-MISSING-PROPERTY", "Element has no shell section", {}});
continue;
}
const auto material_it = domain.materials.find(Domain::key(section->material));
if (material_it == domain.materials.end()) {
result.diagnostics.push_back({Severity::Error, "FESA-ASSEMBLY-MISSING-MATERIAL", "Element material is missing", {}});
result.diagnostics.push_back(
{Severity::Error, "FESA-ASSEMBLY-MISSING-MATERIAL", "Element material is missing", {}});
continue;
}
std::array<Vec3, 4> coordinates{};
@@ -581,7 +121,7 @@ inline AssemblyResult assembleSystem(const Domain& domain, const DofManager& dof
coordinates[i] = domain.nodes.at(element.node_ids[i]).coordinates;
}
const auto stiffness = mitc4ElementStiffness(coordinates, material_it->second.elastic_modulus,
material_it->second.poisson_ratio, section->thickness, options);
material_it->second.poisson_ratio, section->thickness, options);
result.diagnostics.insert(result.diagnostics.end(), stiffness.diagnostics.begin(), stiffness.diagnostics.end());
if (!stiffness.ok()) {
continue;
@@ -614,8 +154,7 @@ inline ReducedSystem projectToReducedSystem(const AssemblyResult& assembly, cons
result.k = DenseMatrix(dofs.freeDofCount(), dofs.freeDofCount());
result.f = std::vector<Real>(static_cast<std::size_t>(dofs.freeDofCount()), 0.0);
result.free_full_indices = dofs.freeFullIndices();
if (assembly.k_full.rows() != assembly.k_full.cols() ||
assembly.k_full.rows() != dofs.fullDofCount() ||
if (assembly.k_full.rows() != assembly.k_full.cols() || assembly.k_full.rows() != dofs.fullDofCount() ||
static_cast<LocalIndex>(assembly.f_full.size()) != dofs.fullDofCount()) {
result.diagnostics.push_back(makeDiagnostic(Severity::Error, "FESA-ASSEMBLY-SIZE",
"Full-space stiffness/load sizes do not match DofManager", "assembly"));
@@ -628,7 +167,8 @@ inline ReducedSystem projectToReducedSystem(const AssemblyResult& assembly, cons
}
if (assembly.reduced_pattern.equation_count != dofs.freeDofCount() || assembly.reduced_pattern.nonzeroCount() == 0) {
result.diagnostics.push_back(makeDiagnostic(Severity::Error, "FESA-SINGULAR-SPARSE-PATTERN",
"Reduced sparse pattern is empty or inconsistent with free DOFs", "assembly"));
"Reduced sparse pattern is empty or inconsistent with free DOFs",
"assembly"));
return result;
}
for (LocalIndex i = 0; i < dofs.freeDofCount(); ++i) {
@@ -656,6 +196,7 @@ struct AnalysisResult {
class Analysis {
public:
virtual ~Analysis() = default;
AnalysisResult run(const Domain& domain) const {
AnalysisResult result;
initialize(domain, result);
@@ -671,6 +212,7 @@ class Analysis {
auto diagnostics = validateDomain(domain);
result.diagnostics.insert(result.diagnostics.end(), diagnostics.begin(), diagnostics.end());
}
virtual void solve(const Domain& domain, AnalysisResult& result) const = 0;
};