joss-2023

patch_test_linear_elastic_implicit.cc
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			/* -------------------------------------------------------------------------- */
			#include "patch_test_linear_fixture.hh"
			/* -------------------------------------------------------------------------- */

			TYPED_TEST(TestPatchTestLinear, Implicit) {
			std::string filename = "material_check_stress_plane_stress.dat";
			if (this->plane_strain)
			filename = "material_check_stress_plane_strain.dat";

			this->initModel(_static, filename);

			auto & solver = this->model->getNonLinearSolver();
			solver.set("max_iterations", 2);
			solver.set("threshold", 2e-4);
			solver.set("convergence_type", _scc_residual);

			this->model->solveStep();

			this->checkDisplacements();
			this->checkStrains();
			this->checkStresses([&](const Matrix<Real> & pstrain) {
			Real nu = this->model->getMaterial(0).get("nu");
			Real E = this->model->getMaterial(0).get("E");

			auto strain = (pstrain + pstrain.transpose()) / 2.;
			auto trace = strain.trace();

			auto lambda = nu * E / ((1 + nu) * (1 - 2 * nu));
			auto mu = E / (2 * (1 + nu));

			if (not this->plane_strain) {
			lambda = nu * E / (1 - nu * nu);
			}

			decltype(strain) stress(this->dim, this->dim);

			if (this->dim == 1) {
			stress(0, 0) = E * strain(0, 0);
			} else {
			for (UInt i = 0; i < this->dim; ++i)
			for (UInt j = 0; j < this->dim; ++j)
			stress(i, j) = (i == j) * lambda * trace + 2 * mu * strain(i, j);
			}

			return stress;
			});
			}