Step 3: nonlinear-mitc4-kinematics-and-recovery

읽어야 할 파일

AGENTS.md
docs/ARCHITECTURE.md
docs/ADR.md
docs/nonlinear-static-newton-raphson/formulation.md
docs/nonlinear-static-newton-raphson/numerical-review.md
docs/nonlinear-static-newton-raphson/io.md
include/fesa/elements/mitc4_shell.h
src/fesa/elements/mitc4_shell.cpp
tests/unit/elements/mitc4_shell_test.cpp
include/fesa/model/shell_geometry.h
src/fesa/model/shell_geometry.cpp
include/fesa/model/model_types.h
include/fesa/results/result_records.h
Step 2 files: include/fesa/elements/finite_rotation.h, src/fesa/elements/finite_rotation.cpp

이전 Step 전제

Step 2 provides finite rotation state and SO(3) Jacobian helpers.

소유 파일

Create: include/fesa/elements/nonlinear_mitc4_shell.h
Create: src/fesa/elements/nonlinear_mitc4_shell.cpp
Create: tests/unit/elements/nonlinear_mitc4_shell_test.cpp
Modify: src/fesa/CMakeLists.txt
Modify: tests/CMakeLists.txt

인터페이스

namespace fesa {

struct NonlinearMitc4TrialDofs {
  std::array<Vector3, 4> displacement;
  std::array<Vector3, 4> rotation_vector;
};

struct NonlinearMitc4RecoveryPoint {
  ShellMidsurfaceLocation location;
  std::array<double, 2> natural_coordinates;
  Mitc4LocalFrame local_frame;
  std::array<double, 8> generalized_strain;
  std::array<double, 8> section_resultant;
  std::array<ShellSectionStressRow, 3> stress;
};

struct NonlinearMitc4Recovery {
  std::array<NonlinearMitc4RecoveryPoint, 4> gauss_points;
  double physical_strain_energy;
};

class NonlinearMitc4Shell {
 public:
  static Result<NonlinearMitc4Shell> Create(
      std::array<const Node*, 4> nodes,
      std::array<ShellNodeInitialFrame, 4> initial_frames,
      const ShellSection& section,
      const LinearElasticMaterial& material);

  Result<NonlinearMitc4Recovery> EvaluateKinematics(
      const NonlinearMitc4TrialDofs& trial) const;
  Result<NonlinearMitc4Recovery> RecoverState(
      const NonlinearMitc4TrialDofs& trial) const;
};

}  // namespace fesa

RED

Add tests first.

NSNR-ELEM-KIN-001: initial undeformed state produces zero generalized strain and zero material stress.
NSNR-ELEM-KIN-001A: NonlinearMitc4Shell::Create requires exactly four Node pointers, four corresponding ShellNodeInitialFrame records, one ShellSection, and one LinearElasticMaterial; invalid or mismatched inputs fail closed.
NSNR-ELEM-KIN-002: fixed-initial Total Lagrangian geometry uses initial midsurface and initial directors.
NSNR-ELEM-KIN-003: current director interpolation for strain uses unnormalized interpolated director where formulation requires it.
NSNR-ELEM-KIN-004: opposed or degenerate director state fails closed.
NSNR-ELEM-KIN-005: small-rotation linear limit matches existing Mitc4Shell recovery within numerical-review tolerance.
NSNR-ELEM-KIN-006: finite rigid translation/rotation produces objective zero physical strain/stress.
NSNR-ELEM-KIN-007: recovery emits exactly four midsurface Gauss rows in ShellMidsurfaceLocation order; each row has generalized strain [E11,E22,2E12,K11,K22,2K12,G13,G23], section resultant [N11,N22,N12,M11,M22,M12,Q13,Q23], and stress positions [BOTTOM,MIDDLE,TOP] with components [S11,S22,S12].
NSNR-ELEM-KIN-008: recovery emits no S33, S13, S23 and no nodal extrapolated/corner/averaged stress.

Run:

cmake --build .harness/build --config Debug
ctest --test-dir .harness/build -C Debug -R "NonlinearMitc4Shell|NonlinearMitc4Recovery" --output-on-failure

Expected: compile or test failure because nonlinear MITC4 files do not exist. Unexpected pass stops.

GREEN

Implement nonlinear MITC4 creation, kinematics, and recovery using approved 2x2x2 integration, MITC4 edge-midpoint shear tying, initial shell frames, homogeneous isotropic materially linear response, fixed-size row shapes, and source-order recovery rows.

VERIFY

cmake --fresh -S . -B .harness/build -G "Visual Studio 18 2026" -A x64 `
  "-DFESA_GTEST_SOURCE_DIR=$gtestSource" `
  "-DMKL_DIR=$mklDir" `
  "-DTBB_DIR=$tbbDir" `
  "-DHDF5_DIR=$hdf5Dir"
cmake --build .harness/build --config Debug
ctest --test-dir .harness/build -C Debug -R "NonlinearMitc4Shell|NonlinearMitc4Recovery" --output-on-failure
ctest --test-dir .harness/build -C Debug --show-only=json-v1
ctest --test-dir .harness/build -C Debug --output-on-failure

Recheck .harness/config.json before default commands.

상태 기록

Update only Step 3 status and one-line result payload. Executor owns timestamps, commits, retry, and advancement.

금지사항

Do not change existing Mitc4Shell behavior. 이유: linear MITC4 reference regression must remain stable.
Do not create stress quantities outside approved schema. 이유: I/O excludes S33/S13/S23 and nodal stress projections.
Do not add residual/tangent solve logic here. 이유: Step 4 owns residual and tangent.

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