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test_structural_mechanics_model_bernoulli_beam_2.cc
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test_structural_mechanics_model_bernoulli_beam_2.cc
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/**
* @file test_structural_mechanics_model_bernoulli_beam_2.cc
*
* @author Fabian Barras <fabian.barras@epfl.ch>
* @author Lucas Frérot <lucas.frerot@epfl.ch>
*
* @date creation: Fri Jul 15 2011
* @date last modification: Sun Oct 19 2014
*
* @brief Computation of the analytical exemple 1.1 in the TGC vol 6
*
* @section LICENSE
*
* Copyright (©) 2010-2012, 2014, 2015 EPFL (Ecole Polytechnique Fédérale de
* Lausanne) Laboratory (LSMS - Laboratoire de Simulation en Mécanique des
* Solides)
*
* Akantu is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* Akantu is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Akantu. If not, see <http://www.gnu.org/licenses/>.
*
*/
/* -------------------------------------------------------------------------- */
#include "aka_common.hh"
#include "mesh.hh"
#include "sparse_matrix_aij.hh"
#include "structural_mechanics_model.hh"
#include "test_gtest_utils.hh"
/* -------------------------------------------------------------------------- */
#include <gtest/gtest.h>
using namespace akantu;
TEST(TestBernoulliBeam2, TestDisplacements) {
constexpr ElementType type = _bernoulli_beam_2;
const UInt ndof = ElementClass<type>::getNbDegreeOfFreedom();
constexpr UInt dim = 2;
Mesh mesh(dim, "test_bernoulli_beam_2");
// Pushing nodes
auto & nodes = mesh.getNodes();
Vector<Real> node = {0, 0};
nodes.push_back(node);
node = {10, 0};
nodes.push_back(node);
node = {18, 0};
nodes.push_back(node);
// Pushing connectivity
mesh.addConnectivityType(type);
auto & connectivity = mesh.getConnectivity(type);
Vector<UInt> element = {0, 1};
connectivity.push_back(element);
element = {1, 2};
connectivity.push_back(element);
StructuralMechanicsModel model(mesh, dim, "test_bernoulli_beam_2");
StructuralMaterial mat;
mat.E = 3e10;
mat.I = 0.0025;
mat.A = 0.01;
model.addMaterial(mat);
mat.E = 3e10;
mat.I = 0.00128;
mat.A = 0.01;
model.addMaterial(mat);
// mat.E = 1;
// mat.I = 1;
// mat.A = 1;
// model.addMaterial(mat);
// model.addMaterial(mat);
model.initFull();
// Boundary conditions
auto boundary = model.getBlockedDOFs().begin(ndof);
// clang-format off
*boundary = {true, true, true}; ++boundary;
*boundary = {false, true, false}; ++boundary;
*boundary = {false, true, false}; ++boundary;
// clang-format on
// Forces
Real M = 3600; // Nm
Real q = -6000; // kN/m
Real L = 10; // m
auto & forces = model.getExternalForce();
forces(2, 2) = -M; // moment on last node
#if 1 // as long as integration is not available
forces(0, 1) = q * L / 2;
forces(0, 2) = q * L * L / 12;
forces(1, 1) = q * L / 2;
forces(1, 2) = -q * L * L / 12;
#else
auto & group = mesh.createElementGroup("lin_force");
group.add({type, 0, _not_ghost});
Vector<Real> lin_force = {0, q, 0};
// a linear force is not actually a *boundary* condition
// it is equivalent to a volume force
model.applyBC(BC::Neumann::FromSameDim(lin_force), group);
#endif
forces(2, 0) = mat.E * mat.A / 18;
// Materials
auto & materials = model.getElementMaterial(type);
materials(0) = 0;
materials(1) = 1;
model.solveStep();
// dynamic_cast<const SparseMatrixAIJ &>(model.getDOFManager().getMatrix("K"))
// .saveMatrix("stiffness.mtx");
auto d1 = model.getDisplacement()(1, 2);
auto d2 = model.getDisplacement()(2, 2);
auto d3 = model.getDisplacement()(1, 0);
Real tol = Math::getTolerance();
EXPECT_NEAR(d1, 5.6 / 4800, tol); // first rotation
EXPECT_NEAR(d2, -3.7 / 4800, tol); // second rotation
EXPECT_NEAR(d3, 10. / 18, tol); // axial deformation
}

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