intelline2intpen.C

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/*
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 *
 *             OOFEM : Object Oriented Finite Element Code
 *
 *               Copyright (C) 1993 - 2025   Borek Patzak
 *
 *
 *
 *       Czech Technical University, Faculty of Civil Engineering,
 *   Department of Structural Mechanics, 166 29 Prague, Czech Republic
 *
 *  This library 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 2.1 of the License, or (at your option) any later version.
 *
 *  This program 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 this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
#include "intelline2intpen.h"
 
#include "dofmanager.h"
#include "fei2dlinelin.h"
#include "fei2dlinequad.h"
#include "gausspoint.h"
#include "gaussintegrationrule.h"
#include "parametermanager.h"
#include "paramkey.h"
 
 
namespace oofem {
REGISTER_Element(IntElLine2IntPen);
 
IntElLine2IntPen::IntElLine2IntPen(int n, Domain * d):IntElLine2(n, d)
{
    numberOfDofMans = 6;
    numberOfGaussPoints = 4;
}
 
 
void
IntElLine2IntPen :: initializeFrom(InputRecord &ir, int priority)
{
    StructuralInterfaceElement :: initializeFrom(ir, priority);
    ParameterManager &ppm = giveDomain()->elementPPM;
    PM_UPDATE_PARAMETER(axisymmode, ppm, ir, this->number, IPK_IntElLine1_axisymmode, priority) ;
}
 
 
FloatArrayF<2>
IntElLine2IntPen :: computeCovarBaseVectorAt(IntegrationPoint *ip) const
{
    //printf("Entering IntElLine2IntPen :: computeCovarBaseVectorAt\n");
 
    // Since we are averaging over the whole element, always evaluate the base vectors at xi = 0.
 
    FloatArray xi_0 = {0.0};
 
    FEInterpolation *interp = this->giveInterpolation();
    FloatMatrix dNdxi;
//    interp->evaldNdxi( dNdxi, ip->giveNaturalCoordinates(), FEIElementGeometryWrapper(this) );
    interp->evaldNdxi( dNdxi, xi_0, FEIElementGeometryWrapper(this) );
 
    FloatArrayF<2> G;
    int numNodes = this->giveNumberOfNodes();
    for ( int i = 1; i <= dNdxi.giveNumberOfRows(); i++ ) {
        double X1_i = 0.5 * ( this->giveNode(i)->giveCoordinate(1) + this->giveNode(i + numNodes / 2)->giveCoordinate(1) ); // (mean) point on the fictious mid surface
        double X2_i = 0.5 * ( this->giveNode(i)->giveCoordinate(2) + this->giveNode(i + numNodes / 2)->giveCoordinate(2) );
        G.at(1) += dNdxi.at(i, 1) * X1_i;
        G.at(2) += dNdxi.at(i, 1) * X2_i;
    }
    return G;
}
 
void
IntElLine2IntPen :: computeStiffnessMatrix(FloatMatrix &answer, MatResponseMode rMode, TimeStep *tStep)
{
    // Computes the stiffness matrix of the receiver K_cohesive = int_A ( N^t * dT/dj * N ) dA
    FloatMatrix N, D, DN;
    bool matStiffSymmFlag = this->giveCrossSection()->isCharacteristicMtrxSymmetric(rMode);
    answer.clear();
 
    FloatMatrix rotationMatGtoL;
    FloatArray u;
 
    // First loop over GP: compute projection of test function and traction.
    // The setting is as follows: we have an interface with quadratic interpolation and we
    // wish to project onto the space of constant functions on each element.
 
    // Projecting the basis functions gives a constant for each basis function.
    FloatMatrix proj_N;
    proj_N.clear();
 
    FloatMatrix proj_DN;
    proj_DN.clear();
 
    double area = 0.;
 
    for ( auto &ip: *this->giveDefaultIntegrationRulePtr() ) {
 
        this->computeNmatrixAt(ip, N);
 
        if ( this->nlGeometry == 0 ) {
            this->giveStiffnessMatrix_Eng(D, rMode, ip, tStep);
        } else if ( this->nlGeometry == 1 ) {
            this->giveStiffnessMatrix_dTdj(D, rMode, ip, tStep);
        } else {
            OOFEM_ERROR("nlgeometry must be 0 or 1!")
        }
 
        this->computeTransformationMatrixAt(ip, rotationMatGtoL);
        D.rotatedWith(rotationMatGtoL, 'n');                      // transform stiffness to global coord system
 
        this->computeNmatrixAt(ip, N);
        DN.beProductOf(D, N);
 
 
        double dA = this->computeAreaAround(ip);
        area += dA;
 
        proj_N.add(dA, N);
        proj_DN.add(dA, DN);
    }
 
//    printf("area: %e\n", area);
    proj_N.times(1./area);
    proj_DN.times(1./area);
 
//    printf("proj_N: "); proj_N.printYourself();
 
    for ( auto &ip: *this->giveDefaultIntegrationRulePtr() ) {
 
        if ( this->nlGeometry == 0 ) {
            this->giveStiffnessMatrix_Eng(D, rMode, ip, tStep);
        } else if ( this->nlGeometry == 1 ) {
            this->giveStiffnessMatrix_dTdj(D, rMode, ip, tStep);
        } else {
            OOFEM_ERROR("nlgeometry must be 0 or 1!")
        }
 
        this->computeTransformationMatrixAt(ip, rotationMatGtoL);
        D.rotatedWith(rotationMatGtoL, 'n');                      // transform stiffness to global coord system
 
        DN.beProductOf(D, proj_N);
 
 
        double dA = this->computeAreaAround(ip);
        if ( matStiffSymmFlag ) {
            answer.plusProductSymmUpper(proj_N, DN, dA);
        } else {
            answer.plusProductUnsym(proj_N, DN, dA);
        }
    }
 
 
    if ( matStiffSymmFlag ) {
        answer.symmetrized();
    }
}
 
 
void
IntElLine2IntPen :: giveInternalForcesVector(FloatArray &answer,
                                                       TimeStep *tStep, int useUpdatedGpRecord)
{
    // Computes internal forces
    // For this element we use an "interior penalty" formulation, where
    // the cohesive zone contribution is weakened, i.e. the traction and
    // test function for the cohesive zone are projected onto a reduced
    // space. The purpose of the projection is to improve the stability
    // properties of the formulation, thereby avoiding traction oscilations.
 
    FloatMatrix N;
    FloatArray u, traction, jump;
 
    this->computeVectorOf(VM_Total, tStep, u);
    // subtract initial displacements, if defined
    if ( initialDisplacements.giveSize() ) {
        u.subtract(initialDisplacements);
    }
 
    // zero answer will resize accordingly when adding first contribution
    answer.clear();
 
 
 
    // First loop over GP: compute projection of test function and traction.
    // The setting is as follows: we have an interface with quadratic interpolation and we
    // wish to project onto the space of constant functions on each element.
 
    // The projection of t becomes a constant
//    FloatArray proj_t;
//    proj_t.clear();
 
 
    FloatArray proj_jump;
    proj_jump.clear();
 
    // Projecting the basis functions gives a constant for each basis function.
    FloatMatrix proj_N;
    proj_N.clear();
 
    double area = 0.;
 
    for ( auto &ip: *this->giveDefaultIntegrationRulePtr() ) {
 
        this->computeNmatrixAt(ip, N);
        jump.beProductOf(N, u);
//        this->computeTraction(traction, ip, jump, tStep);
 
        double dA = this->computeAreaAround(ip);
        area += dA;
 
        proj_jump.add(dA, jump);
        proj_N.add(dA, N);
    }
 
//    printf("area: %e\n", area);
    proj_jump.times(1./area);
    proj_N.times(1./area);
 
//    printf("proj_N: "); proj_N.printYourself();
 
 
    // Second loop over GP: assemble contribution to internal forces as we are used to.
    for ( auto &ip: *this->giveDefaultIntegrationRulePtr() ) {
//        this->computeNmatrixAt(ip, N);
//        jump.beProductOf(N, u);
        this->computeTraction(traction, ip, proj_jump, tStep);
 
        // compute internal cohesive forces as f = N^T*traction dA
        double dA = this->computeAreaAround(ip);
        answer.plusProduct(proj_N, traction, dA);
    }
 
}
 
 
 
} /* namespace oofem */