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main.cpp
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Wed, Feb 19, 00:07

main.cpp
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#include <Eigen/Eigen>
#include <cppmat/cppmat.h>
#include <GooseFEM/GooseFEM.h>
#include <GooseMaterial/GooseMaterial.h>
#include <HDF5pp.h>
// -------------------------------------------------------------------------------------------------
// introduce aliases
using ColD = GooseFEM::ColD;
using T2 = cppmat::cartesian2d::tensor2<double>;
using Mat = GooseMaterial::AmorphousSolid::LinearStrain::Elastic::Cartesian2d::Material;
// =================================================================================================
class Material
{
public:
// class variables
// ---------------
// strain(-rate), stress, background damping [mandatory]
cppmat::matrix<double> eps, sig, alpha;
// mesh dimensions
size_t nelem, nne=4, ndim=2, nip=4;
// constitutive response [customize]
std::vector<Mat> material;
// class functions
// ---------------
// constructor [customize]
Material(size_t nelem, size_t nhard);
// compute stress for a certain element "e" and integration point "k" [mandatory]
void updated_eps(size_t e, size_t k);
// post process variables / functions [customize]
// - potential energy
cppmat::matrix<double> Epot;
// - compute potential energy
void post();
};
// -------------------------------------------------------------------------------------------------
Material::Material(size_t _nelem, size_t _nhard)
{
// copy from input [customize]
nelem = _nelem;
// allocate symmetric tensors and scalars per element, per integration point [mandatory]
eps .resize({nelem,nip,3});
sig .resize({nelem,nip,3});
alpha .resize({nelem,nne });
// set mass-density and background damping [customize]
alpha.setConstant(0.2);
// post variables [customize]
Epot.resize({nelem,nip});
// constitutive response per element (per integration post) [customize]
for ( size_t e = 0 ; e < nelem ; ++e )
{
if ( e < _nhard )
{
Mat mat = Mat(100.,10.);
material.push_back(mat);
}
else
{
Mat mat = Mat(100.,1.);
material.push_back(mat);
}
}
}
// -------------------------------------------------------------------------------------------------
void Material::updated_eps(size_t e, size_t k)
{
// local views of the global arrays (speeds up indexing, and increases readability)
cppmat::cartesian2d::tensor2s<double> Eps, Sig;
// point to correct position in matrix of tensors
Eps.map(&eps(e,k));
// compute stress
Sig = material[e].stress(Eps);
// copy to matrix of tensors
std::copy(Sig.begin(), Sig.end(), &sig(e,k));
}
// -------------------------------------------------------------------------------------------------
void Material::post()
{
#pragma omp parallel
{
// local views of the global arrays (speeds up indexing, and increases readability)
cppmat::cartesian2d::tensor2s<double> Eps;
// loop over all elements / integration points
#pragma omp for
for ( size_t e = 0 ; e < nelem ; ++e )
{
for ( size_t k = 0 ; k < nip ; ++k )
{
// point to correct position in matrix of tensors
Eps.map(&eps(e,k));
// compute energy
Epot(e,k) = material[e].energy(Eps);
}
}
}
}
// =================================================================================================
// introduce aliases
using Mesh = GooseFEM::Mesh::Quad4::Regular;
using Element = GooseFEM::OverdampedDynamics::Diagonal::SmallStrain::Quad4<Material>;
using Simulation = GooseFEM::OverdampedDynamics::Diagonal::Periodic<Element>;
// =================================================================================================
int main()
{
// set simulation parameters
double T = 60. ; // total time
double dt = 1.e-3; // time increment
size_t nx = 40 ; // number of elements in both directions
double gamma = .05 ; // displacement step
// damping and mass-density (to allow conversion)
double alpha = 0.2;
double rho = 1.0;
// class which provides the mesh
Mesh mesh(nx,nx,1.);
// extract information
size_t nodeOrigin = mesh.nodesOrigin();
size_t nelem = mesh.nelem();
size_t nhard = nx*nx/4;
// simulation class
Simulation sim = Simulation(
std::make_unique<Element>(std::make_unique<Material>(nelem,nhard),nelem),
mesh.coor(),
mesh.conn(),
mesh.dofsPeriodic(),
dt
);
// define update in macroscopic deformation gradient
T2 dFbar(0.);
dFbar(0,1) = gamma;
// update the displacement according to the macroscopic deformation gradient update
for ( size_t i = 0 ; i < sim.nnode ; ++i )
for ( size_t j = 0 ; j < sim.ndim ; ++j )
for ( size_t k = 0 ; k < sim.ndim ; ++k )
sim.u(i,j) += dFbar(j,k) * ( sim.x(i,k) - sim.x(nodeOrigin,k) );
// process updates for displacement dependent variables
sim.updated_u();
// output variables
ColD Epot(static_cast<int>(T/dt)); Epot.setZero();
ColD Ekin(static_cast<int>(T/dt)); Ekin.setZero();
ColD t (static_cast<int>(T/dt)); t .setZero();
// mass matrix
ColD M = rho/alpha * sim.D;
// loop over increments
for ( size_t inc = 0 ; inc < static_cast<size_t>(Epot.size()) ; ++inc )
{
// - compute increment
sim.midpoint();
// - store time
t(inc) = sim.t;
// - store total kinetic energy
for ( size_t i = 0 ; i < sim.ndof ; ++i )
Ekin(inc) += .5 * M(i) * std::pow(sim.V(i),2.);
// - store total potential energy
sim.elem->mat->post();
Epot(inc) = sim.elem->mat->Epot.average(sim.elem->vol) * sim.elem->vol.sum();
}
// write to output file
H5p::File f = H5p::File("example.hdf5","w");
f.write("/global/Epot",Epot );
f.write("/global/Ekin",Ekin );
f.write("/global/t" ,t );
f.write("/mesh/coor" ,mesh.coor());
f.write("/mesh/conn" ,mesh.conn());
f.write("/mesh/disp" ,sim.u );
return 0;
}

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