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main.cpp
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Tue, Feb 18, 23:10

main.cpp
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#include <Eigen/Eigen>
#include <GooseFEM/GooseFEM.h>
#include <GooseFEM/ParaView.h>
#include <GMatElastoPlastic/Cartesian3d.h>
#include <highfive/H5Easy.hpp>
namespace GM = GMatElastoPlastic::Cartesian3d;
namespace GF = GooseFEM;
namespace PV = GooseFEM::ParaView::HDF5;
namespace H5 = H5Easy;
int main()
{
// mesh
// ----
// define mesh
GF::Mesh::Quad4::Regular mesh(5*10, 5*10);
// mesh dimensions
size_t nelem = mesh.nelem();
size_t nne = mesh.nne();
size_t ndim = mesh.ndim();
// mesh definitions
xt::xtensor<double,2> coor = mesh.coor();
xt::xtensor<size_t,2> conn = mesh.conn();
xt::xtensor<size_t,2> dofs = mesh.dofs();
xt::xtensor<size_t,2> elmat = mesh.elementMatrix();
// periodicity and fixed displacements DOFs
// ----------------------------------------
// add control nodes
GF::Tyings::Control control(coor, dofs);
coor = control.coor();
dofs = control.dofs();
xt::xtensor<size_t,2> control_dofs = control.controlDofs();
xt::xtensor<size_t,1> control_nodes = control.controlNodes();
// extract fixed DOFs:
// - all control nodes: to prescribe the deformation gradient
// - one node of the mesh: to remove rigid body modes
xt::xtensor<size_t,1> iip = xt::concatenate(xt::xtuple(
xt::reshape_view(control_dofs, {ndim*ndim}),
xt::reshape_view(xt::view(dofs, xt::keep(mesh.nodesOrigin()), xt::all()), {ndim})
));
// get DOF-tyings, reorganise system
GF::Tyings::Periodic tyings(coor, dofs, control_dofs, mesh.nodesPeriodic(), iip);
dofs = tyings.dofs();
// simulation variables
// --------------------
// vector definition:
// provides methods to switch between dofval/nodeval/elemvec, or to manipulate a part of them
GF::VectorPartitionedTyings vector(conn, dofs, tyings.Cdu(), tyings.Cdp(), tyings.Cdi());
// nodal quantities
xt::xtensor<double,2> disp = xt::zeros<double>(coor.shape()); // nodal displacement
xt::xtensor<double,2> du = xt::zeros<double>(coor.shape()); // iterative displacement update
xt::xtensor<double,2> fint = xt::zeros<double>(coor.shape()); // internal force
xt::xtensor<double,2> fext = xt::zeros<double>(coor.shape()); // external force
xt::xtensor<double,2> fres = xt::zeros<double>(coor.shape()); // residual force
// element vectors / matrix
xt::xtensor<double,3> ue = xt::empty<double>({nelem, nne, ndim});
xt::xtensor<double,3> fe = xt::empty<double>({nelem, nne, ndim});
xt::xtensor<double,3> Ke = xt::empty<double>({nelem, nne*ndim, nne*ndim});
// DOF values
xt::xtensor<double,1> Fext = xt::zeros<double>({tyings.nni()});
xt::xtensor<double,1> Fint = xt::zeros<double>({tyings.nni()});
// element/material definition
// ---------------------------
// FEM quadrature
GF::Element::Quad4::QuadraturePlanar elem(vector.AsElement(coor));
size_t nip = elem.nip();
xt::xtensor<double,4> dV = elem.DV(2);
// material model
// even though the problem is 2-d, the material model is 3-d, plane strain is implicitly assumed
GM::Matrix mat(nelem, nip);
size_t tdim = mat.ndim();
// some artificial material definition
xt::xtensor<size_t,1> ehard = xt::ravel(xt::view(elmat, xt::range(0,2*10), xt::range(0,2*10)));
xt::xtensor<size_t,2> Ihard = xt::zeros<size_t>({nelem, nip});
xt::view(Ihard, xt::keep(ehard), xt::all()) = 1ul;
xt::xtensor<size_t,2> Isoft = xt::ones<size_t>({nelem, nip}) - Ihard;
mat.setLinearHardening(Isoft, 1.0, 1.0, 0.05, 0.05);
mat.setElastic(Ihard, 1.0, 1.0);
// solve
// -----
// allocate tensors
xt::xtensor<double,4> Eps = xt::empty<double>({nelem, nip, tdim, tdim});
xt::xtensor<double,4> Sig = xt::empty<double>({nelem, nip, tdim, tdim});
xt::xtensor<double,6> C = xt::empty<double>({nelem, nip, tdim, tdim, tdim, tdim});
// allocate system matrix
GF::MatrixPartitionedTyings<> K(conn, dofs, tyings.Cdu(), tyings.Cdp());
// allocate internal variables
double res;
// some shear strain history
xt::xtensor<double,1> dgamma = 0.001 * xt::ones<double>({101});
dgamma(0) = 0.0;
// initialise output
// - output-file containing data
HighFive::File file("main.h5", HighFive::File::Overwrite);
// - ParaView meta-data
PV::TimeSeries xdmf;
// - write mesh
H5::dump(file, "/conn", conn);
H5::dump(file, "/coor", coor);
// loop over increments
for (size_t inc = 0; inc < dgamma.size(); ++inc)
{
// update history
mat.increment();
// iterate
for (size_t iter = 0; ; ++iter)
{
// strain
vector.asElement(disp, ue);
elem.symGradN_vector(ue, Eps);
// stress & tangent
mat.tangent(Eps, Sig, C);
// internal force
elem.int_gradN_dot_tensor2_dV(Sig, fe);
vector.assembleNode(fe, fint);
// stiffness matrix
elem.int_gradN_dot_tensor4_dot_gradNT_dV(C, Ke);
K.assemble(Ke);
// residual
xt::noalias(fres) = fext - fint;
// check for convergence (skip the zeroth iteration, as the residual still vanishes)
if (iter > 0)
{
// - internal/external force as DOFs (account for periodicity)
vector.asDofs_i(fext, Fext);
vector.asDofs_i(fint, Fint);
// - extract reaction force
vector.copy_p(Fint, Fext);
// - norm of the residual and the reaction force
double nfres = xt::sum(xt::abs(Fext-Fint))[0];
double nfext = xt::sum(xt::abs(Fext))[0];
// - relative residual, for convergence check
if (nfext)
res = nfres / nfext;
else
res = nfres;
// - print progress to screen
std::cout << "inc = " << inc << ", iter = " << iter << ", res = " << res << std::endl;
// - check for convergence
if (res < 1.0e-5)
break;
// - safe-guard from infinite loop
if (iter > 20)
throw std::runtime_error("Maximal number of iterations exceeded");
}
// initialise displacement update
du.fill(0.0);
// set fixed displacements
if (iter == 0)
du(control_nodes(0),1) = dgamma(inc);
// solve
K.solve(fres, du);
// add displacement update
disp += du;
}
// post-process
// - compute strain and stress
vector.asElement(disp, ue);
elem.symGradN_vector(ue, Eps);
mat.stress(Eps, Sig);
// - element average stress
xt::xtensor<double,3> Sigelem = xt::average(Sig, dV, {1});
xt::xtensor<double,3> Epselem = xt::average(Eps, dV, {1});
// - macroscopic strain and stress
xt::xtensor_fixed<double, xt::xshape<3,3>> Sigbar = xt::average(Sig, dV, {0,1});
xt::xtensor_fixed<double, xt::xshape<3,3>> Epsbar = xt::average(Eps, dV, {0,1});
// - write to output-file: increment numbers
H5::dump(file, "/stored", inc, {inc});
// - write to output-file: macroscopic response
H5::dump(file, "/macroscopic/sigeq", GM::Sigeq(Sigbar), {inc});
H5::dump(file, "/macroscopic/epseq", GM::Epseq(Epsbar), {inc});
// - write to output-file: element quantities
H5::dump(file, "/sigeq/" + std::to_string(inc), GM::Sigeq(Sigelem));
H5::dump(file, "/epseq/" + std::to_string(inc), GM::Epseq(Epselem));
H5::dump(file, "/disp/" + std::to_string(inc), PV::as3d(disp));
// - update ParaView meta-data
xdmf.push_back(PV::Increment(
PV::Connectivity(file, "/conn", mesh.getElementType()),
PV::Coordinates (file, "/coor"),
{
PV::Attribute(file, "/disp/" + std::to_string(inc), "Displacement", PV::AttributeType::Node),
PV::Attribute(file, "/sigeq/" + std::to_string(inc), "Eq. stress" , PV::AttributeType::Cell),
PV::Attribute(file, "/epseq/" + std::to_string(inc), "Eq. strain" , PV::AttributeType::Cell),
}
));
}
// write ParaView meta-data
xdmf.write("main.xdmf");
return 0;
}

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