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/*=========================================================================
*
* Copyright NumFOCUS
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
#ifndef itkFEMElement1DStress_hxx
#define itkFEMElement1DStress_hxx
#include "itkFEMMaterialLinearElasticity.h"
namespace itk
{
namespace fem
{
template <typename TBaseClass>
Element1DStress<TBaseClass>::Element1DStress()
: Superclass()
{}
// ////////////////////////////////////////////////////////////////////////
/**
* Methods related to the physics of the problem.
*/
template <typename TBaseClass>
void
Element1DStress<TBaseClass>::GetStrainDisplacementMatrix(MatrixType & B, const MatrixType & shapeDgl) const
{
B.set_size(1, 2);
// Copy the shape function derivatives to the B matrix.
B[0][0] = shapeDgl[0][0];
B[0][1] = shapeDgl[0][1];
}
template <typename TBaseClass>
void
Element1DStress<TBaseClass>::GetMaterialMatrix(MatrixType & D) const
{
D.set_size(1, 1);
D.fill(0.0);
// Material properties matrix is a scalar
D[0][0] = m_mat->GetYoungsModulus() * m_mat->GetCrossSectionalArea();
}
template <typename TBaseClass>
void
Element1DStress<TBaseClass>::GetStiffnessMatrix(MatrixType & Ke) const
{
const unsigned int Ndims = this->GetNumberOfSpatialDimensions();
const unsigned int Nn = this->GetNumberOfNodes();
// First we obtain the Ke by calling the parent's
// GetStiffnessMatrix function. This is the stiffness matrix
// with only one DOF per node.
Superclass::GetStiffnessMatrix(Ke);
// Calculate the nodal displacement transformation matrix according
// to the number of dimensions in global coordinate system
MatrixType T(2, 2 * Ndims, 0.0);
VectorType d = this->GetNodeCoordinates(1) - this->GetNodeCoordinates(0);
d = d / d.magnitude();
for (unsigned int i = 0; i < Ndims; ++i)
{
for (unsigned int n = 0; n < Nn; ++n)
{
T[n][n * Ndims + i] = d[i];
}
}
// Apply the nodal displacement transformation matrix to original
// element stiffness matrix to obtain the element stiffness
// matrix in global coordinates.
Ke = T.transpose() * Ke * T;
}
template <typename TBaseClass>
void
Element1DStress<TBaseClass>::PrintSelf(std::ostream & os, Indent indent) const
{
Superclass::PrintSelf(os, indent);
os << indent << "Young Modulus: " << this->m_mat << std::endl;
}
} // end namespace fem
} // end namespace itk
#endif
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