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rGOOSEFEM GooseFEM
ElementQuad4.hpp
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/* =================================================================================================
(c - GPLv3) T.W.J. de Geus (Tom) | tom@geus.me | www.geus.me | github.com/tdegeus/GooseFEM
================================================================================================= */
#ifndef GOOSEFEM_ELEMENTQUAD4_CPP
#define GOOSEFEM_ELEMENTQUAD4_CPP
// -------------------------------------------------------------------------------------------------
#include "ElementQuad4.h"
// =================================================================================================
namespace GooseFEM {
namespace Element {
namespace Quad4 {
// =================================================================================================
inline double inv(const T2 &A, T2 &Ainv)
{
// compute determinant
double det = A(0,0) * A(1,1) - A(0,1) * A(1,0);
// compute inverse
Ainv(0,0) = A(1,1) / det;
Ainv(0,1) = -1. * A(0,1) / det;
Ainv(1,0) = -1. * A(1,0) / det;
Ainv(1,1) = A(0,0) / det;
return det;
}
// =================================================================================================
namespace Gauss {
// -------------------------------------------------------------------------------------------------
inline size_t nip()
{
return 4;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,2> xi()
{
size_t nip = 4;
size_t ndim = 2;
xt::xtensor<double,2> xi = xt::empty<double>({nip,ndim});
xi(0,0) = -1./std::sqrt(3.); xi(0,1) = -1./std::sqrt(3.);
xi(1,0) = +1./std::sqrt(3.); xi(1,1) = -1./std::sqrt(3.);
xi(2,0) = +1./std::sqrt(3.); xi(2,1) = +1./std::sqrt(3.);
xi(3,0) = -1./std::sqrt(3.); xi(3,1) = +1./std::sqrt(3.);
return xi;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,1> w()
{
size_t nip = 4;
xt::xtensor<double,1> w = xt::empty<double>({nip});
w(0) = 1.;
w(1) = 1.;
w(2) = 1.;
w(3) = 1.;
return w;
}
// -------------------------------------------------------------------------------------------------
}
// =================================================================================================
namespace Nodal {
// -------------------------------------------------------------------------------------------------
inline size_t nip()
{
return 4;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,2> xi()
{
size_t nip = 4;
size_t ndim = 2;
xt::xtensor<double,2> xi = xt::empty<double>({nip,ndim});
xi(0,0) = -1.; xi(0,1) = -1.;
xi(1,0) = +1.; xi(1,1) = -1.;
xi(2,0) = +1.; xi(2,1) = +1.;
xi(3,0) = -1.; xi(3,1) = +1.;
return xi;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,1> w()
{
size_t nip = 4;
xt::xtensor<double,1> w = xt::empty<double>({nip});
w(0) = 1.;
w(1) = 1.;
w(2) = 1.;
w(3) = 1.;
return w;
}
// -------------------------------------------------------------------------------------------------
}
// =================================================================================================
inline Quadrature::Quadrature(const xt::xtensor<double,3> &x, const xt::xtensor<double,2> &xi,
const xt::xtensor<double,1> &w) : m_x(x), m_w(w), m_xi(xi)
{
// check input
assert( m_x.shape()[1] == m_nne );
assert( m_x.shape()[2] == m_ndim );
// extract number of elements and number of integration points
m_nelem = m_x.shape()[0];
m_nip = m_w.size();
// check input
assert( m_xi.shape()[0] == m_nip );
assert( m_xi.shape()[1] == m_ndim );
assert( m_w .size() == m_nip );
// allocate arrays
m_N = xt::empty<double>({ m_nip, m_nne });
m_dNxi = xt::empty<double>({ m_nip, m_nne, m_ndim});
m_dNx = xt::empty<double>({m_nelem, m_nip, m_nne, m_ndim});
m_vol = xt::empty<double>({m_nelem, m_nip });
// shape functions
for ( size_t q = 0 ; q < m_nip ; ++q )
{
m_N(q,0) = .25 * (1.-m_xi(q,0)) * (1.-m_xi(q,1));
m_N(q,1) = .25 * (1.+m_xi(q,0)) * (1.-m_xi(q,1));
m_N(q,2) = .25 * (1.+m_xi(q,0)) * (1.+m_xi(q,1));
m_N(q,3) = .25 * (1.-m_xi(q,0)) * (1.+m_xi(q,1));
}
// shape function gradients in local coordinates
for ( size_t q = 0 ; q < m_nip ; ++q )
{
// - dN / dxi_0
m_dNxi(q,0,0) = -.25*(1.-m_xi(q,1));
m_dNxi(q,1,0) = +.25*(1.-m_xi(q,1));
m_dNxi(q,2,0) = +.25*(1.+m_xi(q,1));
m_dNxi(q,3,0) = -.25*(1.+m_xi(q,1));
// - dN / dxi_1
m_dNxi(q,0,1) = -.25*(1.-m_xi(q,0));
m_dNxi(q,1,1) = -.25*(1.+m_xi(q,0));
m_dNxi(q,2,1) = +.25*(1.+m_xi(q,0));
m_dNxi(q,3,1) = +.25*(1.-m_xi(q,0));
}
// compute the shape function gradients, based on "x"
compute_dN();
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::dV(xt::xtensor<double,2> &qscalar) const
{
assert( qscalar.shape()[0] == m_nelem );
assert( qscalar.shape()[1] == m_nip );
#pragma omp parallel for
for ( size_t e = 0 ; e < m_nelem ; ++e )
for ( size_t q = 0 ; q < m_nip ; ++q )
qscalar(e,q) = m_vol(e,q);
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::dV(xt::xtensor<double,4> &qtensor) const
{
assert( qtensor.shape()[0] == m_nelem );
assert( qtensor.shape()[1] == m_nne );
assert( qtensor.shape()[2] == m_ndim );
assert( qtensor.shape()[3] == m_ndim );
#pragma omp parallel for
for ( size_t e = 0 ; e < m_nelem ; ++e )
for ( size_t q = 0 ; q < m_nip ; ++q )
for ( size_t i = 0 ; i < m_ndim ; ++i )
for ( size_t j = 0 ; j < m_ndim ; ++j )
qtensor(e,q,i,j) = m_vol(e,q);
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::update_x(const xt::xtensor<double,3> &x)
{
assert( x.shape()[0] == m_nelem );
assert( x.shape()[1] == m_nne );
assert( x.shape()[2] == m_ndim );
assert( x.size() == m_x.size() );
// update positions
xt::noalias(m_x) = x;
// update the shape function gradients for the new "x"
compute_dN();
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::compute_dN()
{
// loop over all elements (in parallel)
#pragma omp parallel
{
// allocate local variables
T2 J, Jinv;
#pragma omp for
for ( size_t e = 0 ; e < m_nelem ; ++e )
{
// alias nodal positions
auto x = xt::adapt(&m_x(e,0,0), xt::xshape<m_nne,m_ndim>());
// loop over integration points
for ( size_t q = 0 ; q < m_nip ; ++q )
{
// - alias
auto dNxi = xt::adapt(&m_dNxi( q,0,0), xt::xshape<m_nne,m_ndim>());
auto dNx = xt::adapt(&m_dNx (e,q,0,0), xt::xshape<m_nne,m_ndim>());
// - Jacobian (loops unrolled for efficiency)
// J(i,j) += dNxi(m,i) * x(m,j);
J(0,0) = dNxi(0,0)*x(0,0) + dNxi(1,0)*x(1,0) + dNxi(2,0)*x(2,0) + dNxi(3,0)*x(3,0);
J(0,1) = dNxi(0,0)*x(0,1) + dNxi(1,0)*x(1,1) + dNxi(2,0)*x(2,1) + dNxi(3,0)*x(3,1);
J(1,0) = dNxi(0,1)*x(0,0) + dNxi(1,1)*x(1,0) + dNxi(2,1)*x(2,0) + dNxi(3,1)*x(3,0);
J(1,1) = dNxi(0,1)*x(0,1) + dNxi(1,1)*x(1,1) + dNxi(2,1)*x(2,1) + dNxi(3,1)*x(3,1);
// - determinant and inverse of the Jacobian
double Jdet = inv(J, Jinv);
// - shape function gradients wrt global coordinates (loops partly unrolled for efficiency)
// dNx(m,i) += Jinv(i,j) * dNxi(m,j);
for ( size_t m = 0 ; m < m_nne ; ++m )
{
dNx(m,0) = Jinv(0,0) * dNxi(m,0) + Jinv(0,1) * dNxi(m,1);
dNx(m,1) = Jinv(1,0) * dNxi(m,0) + Jinv(1,1) * dNxi(m,1);
}
// - integration point volume
m_vol(e,q) = m_w(q) * Jdet;
}
}
}
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::gradN_vector(
const xt::xtensor<double,3> &elemvec, xt::xtensor<double,4> &qtensor) const
{
assert( elemvec.shape()[0] == m_nelem );
assert( elemvec.shape()[1] == m_nne );
assert( elemvec.shape()[2] == m_ndim );
assert( qtensor.shape()[0] == m_nelem );
assert( qtensor.shape()[1] == m_nne );
assert( qtensor.shape()[2] == m_ndim );
assert( qtensor.shape()[3] == m_ndim );
// zero-initialize output: matrix of tensors
qtensor.fill(0.0);
// loop over all elements (in parallel)
#pragma omp parallel for
for ( size_t e = 0 ; e < m_nelem ; ++e )
{
// alias element vector (e.g. nodal displacements)
auto u = xt::adapt(&elemvec(e,0,0), xt::xshape<m_nne,m_ndim>());
// loop over all integration points in element "e"
for ( size_t q = 0 ; q < m_nip ; ++q )
{
// - alias
auto dNx = xt::adapt(&m_dNx (e,q,0,0), xt::xshape<m_nne ,m_ndim>());
auto gradu = xt::adapt(&qtensor(e,q,0,0), xt::xshape<m_ndim,m_ndim>());
// - evaluate dyadic product (loops unrolled for efficiency)
// gradu(i,j) += dNx(m,i) * u(m,j)
gradu(0,0) = dNx(0,0)*u(0,0) + dNx(1,0)*u(1,0) + dNx(2,0)*u(2,0) + dNx(3,0)*u(3,0);
gradu(0,1) = dNx(0,0)*u(0,1) + dNx(1,0)*u(1,1) + dNx(2,0)*u(2,1) + dNx(3,0)*u(3,1);
gradu(1,0) = dNx(0,1)*u(0,0) + dNx(1,1)*u(1,0) + dNx(2,1)*u(2,0) + dNx(3,1)*u(3,0);
gradu(1,1) = dNx(0,1)*u(0,1) + dNx(1,1)*u(1,1) + dNx(2,1)*u(2,1) + dNx(3,1)*u(3,1);
}
}
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::gradN_vector_T(
const xt::xtensor<double,3> &elemvec, xt::xtensor<double,4> &qtensor) const
{
assert( elemvec.shape()[0] == m_nelem );
assert( elemvec.shape()[1] == m_nne );
assert( elemvec.shape()[2] == m_ndim );
assert( qtensor.shape()[0] == m_nelem );
assert( qtensor.shape()[1] == m_nne );
assert( qtensor.shape()[2] == m_ndim );
assert( qtensor.shape()[3] == m_ndim );
// zero-initialize output: matrix of tensors
qtensor.fill(0.0);
// loop over all elements (in parallel)
#pragma omp parallel for
for ( size_t e = 0 ; e < m_nelem ; ++e )
{
// alias element vector (e.g. nodal displacements)
auto u = xt::adapt(&elemvec(e,0,0), xt::xshape<m_nne,m_ndim>());
// loop over all integration points in element "e"
for ( size_t q = 0 ; q < m_nip ; ++q )
{
// - alias
auto dNx = xt::adapt(&m_dNx (e,q,0,0), xt::xshape<m_nne ,m_ndim>());
auto gradu = xt::adapt(&qtensor(e,q,0,0), xt::xshape<m_ndim,m_ndim>());
// - evaluate transpose of dyadic product (loops unrolled for efficiency)
// gradu(j,i) += dNx(m,i) * u(m,j)
gradu(0,0) = dNx(0,0)*u(0,0) + dNx(1,0)*u(1,0) + dNx(2,0)*u(2,0) + dNx(3,0)*u(3,0);
gradu(1,0) = dNx(0,0)*u(0,1) + dNx(1,0)*u(1,1) + dNx(2,0)*u(2,1) + dNx(3,0)*u(3,1);
gradu(0,1) = dNx(0,1)*u(0,0) + dNx(1,1)*u(1,0) + dNx(2,1)*u(2,0) + dNx(3,1)*u(3,0);
gradu(1,1) = dNx(0,1)*u(0,1) + dNx(1,1)*u(1,1) + dNx(2,1)*u(2,1) + dNx(3,1)*u(3,1);
}
}
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::symGradN_vector(
const xt::xtensor<double,3> &elemvec, xt::xtensor<double,4> &qtensor) const
{
assert( elemvec.shape()[0] == m_nelem );
assert( elemvec.shape()[1] == m_nne );
assert( elemvec.shape()[2] == m_ndim );
assert( qtensor.shape()[0] == m_nelem );
assert( qtensor.shape()[1] == m_nne );
assert( qtensor.shape()[2] == m_ndim );
assert( qtensor.shape()[3] == m_ndim );
// zero-initialize output: matrix of tensors
qtensor.fill(0.0);
// loop over all elements (in parallel)
#pragma omp parallel for
for ( size_t e = 0 ; e < m_nelem ; ++e )
{
// alias element vector (e.g. nodal displacements)
auto u = xt::adapt(&elemvec(e,0,0), xt::xshape<m_nne,m_ndim>());
// loop over all integration points in element "e"
for ( size_t q = 0 ; q < m_nip ; ++q )
{
// - alias
auto dNx = xt::adapt(&m_dNx (e,q,0,0), xt::xshape<m_nne ,m_ndim>());
auto eps = xt::adapt(&qtensor(e,q,0,0), xt::xshape<m_ndim,m_ndim>());
// - evaluate symmetrized dyadic product (loops unrolled for efficiency)
// grad(i,j) += dNx(m,i) * u(m,j)
// eps (j,i) = 0.5 * ( grad(i,j) + grad(j,i) )
eps(0,0) = dNx(0,0)*u(0,0) + dNx(1,0)*u(1,0) + dNx(2,0)*u(2,0) + dNx(3,0)*u(3,0);
eps(1,1) = dNx(0,1)*u(0,1) + dNx(1,1)*u(1,1) + dNx(2,1)*u(2,1) + dNx(3,1)*u(3,1);
eps(0,1) = ( dNx(0,0)*u(0,1) + dNx(1,0)*u(1,1) + dNx(2,0)*u(2,1) + dNx(3,0)*u(3,1) +
dNx(0,1)*u(0,0) + dNx(1,1)*u(1,0) + dNx(2,1)*u(2,0) + dNx(3,1)*u(3,0) ) * 0.5;
eps(1,0) = eps(0,1);
}
}
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::int_N_scalar_NT_dV(
const xt::xtensor<double,2> &qscalar, xt::xtensor<double,3> &elemmat) const
{
assert( qscalar.shape()[0] == m_nelem );
assert( qscalar.shape()[1] == m_nip );
assert( elemmat.shape()[0] == m_nelem );
assert( elemmat.shape()[1] == m_nne*m_ndim );
assert( elemmat.shape()[2] == m_nne*m_ndim );
// zero-initialize: matrix of matrices
elemmat.fill(0.0);
// loop over all elements (in parallel)
#pragma omp parallel for
for ( size_t e = 0 ; e < m_nelem ; ++e )
{
// alias (e.g. mass matrix)
auto M = xt::adapt(&elemmat(e,0,0), xt::xshape<m_nne*m_ndim,m_nne*m_ndim>());
// loop over all integration points in element "e"
for ( size_t q = 0 ; q < m_nip ; ++q )
{
// - alias
auto N = xt::adapt(&m_N(q,0), xt::xshape<m_nne>());
auto& vol = m_vol (e,q);
auto& rho = qscalar(e,q);
// - evaluate scalar product, for all dimensions, and assemble
// M(m*ndim+i,n*ndim+i) += N(m) * scalar * N(n) * dV
for ( size_t m = 0 ; m < m_nne ; ++m ) {
for ( size_t n = 0 ; n < m_nne ; ++n ) {
M(m*m_ndim+0, n*m_ndim+0) += N(m) * rho * N(n) * vol;
M(m*m_ndim+1, n*m_ndim+1) += N(m) * rho * N(n) * vol;
}
}
}
}
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::int_gradN_dot_tensor2_dV(const xt::xtensor<double,4> &qtensor,
xt::xtensor<double,3> &elemvec) const
{
assert( qtensor.shape()[0] == m_nelem );
assert( qtensor.shape()[1] == m_nip );
assert( qtensor.shape()[2] == m_ndim );
assert( qtensor.shape()[3] == m_ndim );
assert( elemvec.shape()[0] == m_nelem );
assert( elemvec.shape()[1] == m_nne );
assert( elemvec.shape()[2] == m_ndim );
// zero-initialize output: matrix of vectors
elemvec.fill(0.0);
// loop over all elements (in parallel)
#pragma omp parallel for
for ( size_t e = 0 ; e < m_nelem ; ++e )
{
// alias (e.g. nodal force)
auto f = xt::adapt(&elemvec(e,0,0), xt::xshape<m_nne,m_ndim>());
// loop over all integration points in element "e"
for ( size_t q = 0 ; q < m_nip ; ++q )
{
// - alias
auto dNx = xt::adapt(&m_dNx (e,q,0,0), xt::xshape<m_nne ,m_ndim>());
auto sig = xt::adapt(&qtensor(e,q,0,0), xt::xshape<m_ndim,m_ndim>());
auto& vol = m_vol(e,q);
// - evaluate dot product, and assemble
for ( size_t m = 0 ; m < m_nne ; ++m )
{
f(m,0) += ( dNx(m,0) * sig(0,0) + dNx(m,1) * sig(1,0) ) * vol;
f(m,1) += ( dNx(m,0) * sig(0,1) + dNx(m,1) * sig(1,1) ) * vol;
}
}
}
}
// -------------------------------------------------------------------------------------------------
inline void Quadrature::int_gradN_dot_tensor4_dot_gradNT_dV(const xt::xtensor<double,6> &qtensor,
xt::xtensor<double,3> &elemmat) const
{
assert( qtensor.shape()[0] == m_nelem );
assert( qtensor.shape()[1] == m_nip );
assert( qtensor.shape()[2] == m_ndim );
assert( qtensor.shape()[3] == m_ndim );
assert( qtensor.shape()[4] == m_ndim );
assert( qtensor.shape()[5] == m_ndim );
assert( elemmat.shape()[0] == m_nelem );
assert( elemmat.shape()[1] == m_nne*m_ndim );
assert( elemmat.shape()[2] == m_nne*m_ndim );
// zero-initialize output: matrix of vector
elemmat.fill(0.0);
// loop over all elements (in parallel)
#pragma omp parallel for
for ( size_t e = 0 ; e < m_nelem ; ++e )
{
// alias (e.g. nodal force)
auto K = xt::adapt(&elemmat(e,0,0), xt::xshape<m_nne*m_ndim,m_nne*m_ndim>());
// loop over all integration points in element "e"
for ( size_t q = 0 ; q < m_nip ; ++q ){
// - alias
auto dNx = xt::adapt(&m_dNx(e,q,0,0), xt::xshape<m_nne,m_ndim>());
auto C = xt::adapt(&qtensor(e,q,0,0,0,0), xt::xshape<m_ndim,m_ndim,m_ndim,m_ndim>());
auto& vol = m_vol(e,q);
// - evaluate dot product, and assemble
for ( size_t m = 0 ; m < m_nne ; ++m )
for ( size_t n = 0 ; n < m_nne ; ++n )
for ( size_t i = 0 ; i < m_ndim ; ++i )
for ( size_t j = 0 ; j < m_ndim ; ++j )
for ( size_t k = 0 ; k < m_ndim ; ++k )
for ( size_t l = 0 ; l < m_ndim ; ++l )
K(m*m_ndim+j, n*m_ndim+k) += dNx(m,i) * C(i,j,k,l) * dNx(n,l) * vol;
}
}
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,2> Quadrature::dV() const
{
xt::xtensor<double,2> out = xt::empty<double>({m_nelem, m_nip});
this->dV(out);
return out;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,4> Quadrature::dVtensor() const
{
xt::xtensor<double,4> out = xt::empty<double>({m_nelem, m_nip, m_ndim, m_ndim});
this->dV(out);
return out;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,4> Quadrature::gradN_vector(const xt::xtensor<double,3> &elemvec) const
{
xt::xtensor<double,4> qtensor = xt::empty<double>({m_nelem, m_nip, m_ndim, m_ndim});
this->gradN_vector(elemvec, qtensor);
return qtensor;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,4> Quadrature::gradN_vector_T(const xt::xtensor<double,3> &elemvec) const
{
xt::xtensor<double,4> qtensor = xt::empty<double>({m_nelem, m_nip, m_ndim, m_ndim});
this->gradN_vector_T(elemvec, qtensor);
return qtensor;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,4> Quadrature::symGradN_vector(const xt::xtensor<double,3> &elemvec) const
{
xt::xtensor<double,4> qtensor = xt::empty<double>({m_nelem, m_nip, m_ndim, m_ndim});
this->symGradN_vector(elemvec, qtensor);
return qtensor;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,3> Quadrature::int_N_scalar_NT_dV(
const xt::xtensor<double,2> &qscalar) const
{
xt::xtensor<double,3> elemmat = xt::empty<double>({m_nelem, m_nne*m_ndim, m_nne*m_ndim});
this->int_N_scalar_NT_dV(qscalar, elemmat);
return elemmat;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,3> Quadrature::int_gradN_dot_tensor2_dV(
const xt::xtensor<double,4> &qtensor) const
{
xt::xtensor<double,3> elemvec = xt::empty<double>({m_nelem, m_nne, m_ndim});
this->int_gradN_dot_tensor2_dV(qtensor, elemvec);
return elemvec;
}
// -------------------------------------------------------------------------------------------------
inline xt::xtensor<double,3> Quadrature::int_gradN_dot_tensor4_dot_gradNT_dV(
const xt::xtensor<double,6> &qtensor) const
{
xt::xtensor<double,3> elemmat = xt::empty<double>({m_nelem, m_ndim*m_nne, m_ndim*m_nne});
this->int_gradN_dot_tensor4_dot_gradNT_dV(qtensor, elemmat);
return elemmat;
}
// -------------------------------------------------------------------------------------------------
}}} // namespace ...
// =================================================================================================
#endif
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