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EnhancedQuad.cpp Go to the documentation of this file. /* ****************************************************************** ** ** OpenSees - Open System for Earthquake Engineering Simulation ** ** Pacific Earthquake Engineering Research Center ** ** ** ** ** ** (C) Copyright 1999, The Regents of the University of California ** ** All Rights Reserved. ** ** ** ** Commercial use of this program without express permission of the ** ** University of California, Berkeley, is strictly prohibited. See ** ** file 'COPYRIGHT' in main directory for information on usage and ** ** redistribution, and for a DISCLAIMER OF ALL WARRANTIES. ** ** ** ** Developed by: ** ** Frank McKenna (fmckenna@ce.berkeley.edu) ** ** Gregory L. Fenves (fenves@ce.berkeley.edu) ** ** Filip C. Filippou (filippou@ce.berkeley.edu) ** ** ** ** ****************************************************************** */ // $Revision: 1.1 $ // $Date: 2001/07/11 22:59:25 $ // $Source: /usr/local/cvs/OpenSees/SRC/element/fourNodeQuad/EnhancedQuad.cpp,v $ #include <iostream.h> #include <stdio.h> #include <stdlib.h> #include <math.h> #include <ID.h> #include <Vector.h> #include <Matrix.h> #include <Element.h> #include <Node.h> #include <NDMaterial.h> #include <Domain.h> #include <ErrorHandler.h> #include <EnhancedQuad.h> #include <Renderer.h> //static data double EnhancedQuad::xl[2][4] ; Matrix EnhancedQuad::stiff(8,8) ; Vector EnhancedQuad::resid(8) ; Matrix EnhancedQuad::mass(8,8) ; Matrix EnhancedQuad::damping(8,8) ; double EnhancedQuad::stressData[3][4] ; double EnhancedQuad::tangentData[3][3][4] ; //quadrature data const double EnhancedQuad::root3 = sqrt(3.0) ; const double EnhancedQuad::one_over_root3 = 1.0 / root3 ; const double EnhancedQuad::sg[] = { -one_over_root3, one_over_root3, one_over_root3, -one_over_root3 } ; const double EnhancedQuad::tg[] = { -one_over_root3, -one_over_root3, one_over_root3, one_over_root3 } ; const double EnhancedQuad::wg[] = { 1.0, 1.0, 1.0, 1.0 } ; //null constructor EnhancedQuad::EnhancedQuad( ) : Element( 0, ELE_TAG_EnhancedQuad ), connectedExternalNodes(4), alpha(4) { } //full constructor EnhancedQuad::EnhancedQuad( int tag, int node1, int node2, int node3, int node4, NDMaterial &theMaterial, const char *type ) : Element( tag, ELE_TAG_EnhancedQuad ), connectedExternalNodes(4), alpha(4) { connectedExternalNodes(0) = node1 ; connectedExternalNodes(1) = node2 ; connectedExternalNodes(2) = node3 ; connectedExternalNodes(3) = node4 ; int i ; for ( i = 0 ; i < 4; i++ ) { materialPointers[i] = theMaterial.getCopy(type) ; if (materialPointers[i] == 0) { g3ErrorHandler->fatal("EnhancedQuad::constructor %s", "- failed to get a material of type: ShellSection"); } //end if } //end for i } //destructor EnhancedQuad::~EnhancedQuad( ) { int i ; for ( i = 0 ; i < 4; i++ ) { delete materialPointers[i] ; materialPointers[i] = 0 ; nodePointers[i] = 0 ; } //end for i } //set domain void EnhancedQuad::setDomain( Domain *theDomain ) { int i ; //zero enhanced parameters alpha.Zero( ) ; //node pointers for ( i = 0; i < 4; i++ ) nodePointers[i] = theDomain->getNode( connectedExternalNodes(i) ) ; this->DomainComponent::setDomain(theDomain) ; } //get the number of external nodes int EnhancedQuad::getNumExternalNodes( ) const { return 4 ; } //return connected external nodes const ID& EnhancedQuad::getExternalNodes( ) { return connectedExternalNodes ; } //return number of dofs int EnhancedQuad::getNumDOF( ) { return 8 ; } //commit state int EnhancedQuad::commitState( ) { int i ; int success = 0 ; for ( i = 0; i < 4; i++ ) success += materialPointers[i]->commitState( ) ; return success ; } //revert to last commit int EnhancedQuad::revertToLastCommit( ) { int i ; int success = 0 ; for ( i = 0; i < 4; i++ ) success += materialPointers[i]->revertToLastCommit( ) ; return success ; } //revert to start int EnhancedQuad::revertToStart( ) { int i ; int success = 0 ; //zero enhanced parameters this->alpha.Zero( ) ; for ( i = 0; i < 4; i++ ) success += materialPointers[i]->revertToStart( ) ; return success ; } //print out element data void EnhancedQuad::Print( ostream &s, int flag ) { s << '\n' ; s << "Enhanced Strain Four Node Quad \n" ; s << "Node 1 : " << connectedExternalNodes(0) << '\n' ; s << "Node 2 : " << connectedExternalNodes(1) << '\n' ; s << "Node 3 : " << connectedExternalNodes(2) << '\n' ; s << "Node 4 : " << connectedExternalNodes(3) << '\n' ; s << "Material Information : \n " ; materialPointers[0]->Print( s, flag ) ; s << endl ; } //return stiffness matrix const Matrix& EnhancedQuad::getTangentStiff( ) { int tang_flag = 1 ; //get the tangent //do tangent and residual here formResidAndTangent( tang_flag ) ; return stiff ; } //return secant matrix const Matrix& EnhancedQuad::getSecantStiff( ) { int tang_flag = 1 ; //get the tangent //do tangent and residual here formResidAndTangent( tang_flag ) ; return stiff ; } //return damping matrix because frank is a dumb ass const Matrix& EnhancedQuad::getDamp( ) { //not supported return damping ; } //return mass matrix const Matrix& EnhancedQuad::getMass( ) { int tangFlag = 1 ; formInertiaTerms( tangFlag ) ; return mass ; } //zero the load -- what load? void EnhancedQuad::zeroLoad( ) { return ; } //add load -- what load? int EnhancedQuad::addLoad( const Vector &addP ) { return -1 ; } //get residual const Vector& EnhancedQuad::getResistingForce( ) { int tang_flag = 0 ; //don't get the tangent formResidAndTangent( tang_flag ) ; return resid ; } //get residual with inertia terms const Vector& EnhancedQuad::getResistingForceIncInertia( ) { int tang_flag = 0 ; //don't get the tangent //do tangent and residual here formResidAndTangent( tang_flag ) ; //inertia terms formInertiaTerms( tang_flag ) ; return resid ; } //********************************************************************* //form inertia terms void EnhancedQuad::formInertiaTerms( int tangFlag ) { static const int ndm = 2 ; static const int ndf = 2 ; static const int numberNodes = 4 ; static const int numberGauss = 4 ; static const int nShape = 3 ; static const int massIndex = nShape - 1 ; double xsj ; // determinant jacaobian matrix double dvol ; //volume element static double shp[nShape][numberNodes] ; //shape functions at a gauss point static Vector momentum(ndf) ; int i, j, k, p ; int jj, kk ; double temp, rho, massJK ; //zero mass mass.Zero( ) ; //compute basis vectors and local nodal coordinates computeBasis( ) ; //gauss loop for ( i = 0; i < numberGauss; i++ ) { //get shape functions shape2d( sg[i], tg[i], xl, shp, xsj ) ; //volume element dvol = wg[i] * xsj ; //node loop to compute acceleration momentum.Zero( ) ; for ( j = 0; j < numberNodes; j++ ) momentum += shp[massIndex][j] * ( nodePointers[j]->getTrialAccel() ) ; //density rho = materialPointers[i]->getRho() ; //multiply acceleration by density to form momentum momentum *= rho ; //residual and tangent calculations node loops jj = 0 ; for ( j = 0; j < numberNodes; j++ ) { temp = shp[massIndex][j] * dvol ; for ( p = 0; p < ndf; p++ ) resid( jj+p ) += ( temp * momentum(p) ) ; if ( tangFlag == 1 ) { //multiply by density temp *= rho ; //node-node mass kk = 0 ; for ( k = 0; k < numberNodes; k++ ) { massJK = temp * shp[massIndex][k] ; for ( p = 0; p < ndf; p++ ) mass( jj+p, kk+p ) += massJK ; kk += ndf ; } // end for k loop } // end if tang_flag jj += ndf ; } // end for j loop } //end for i gauss loop } //********************************************************************* //form residual and tangent void EnhancedQuad::formResidAndTangent( int tang_flag ) { static const double tolerance = 1.0e-08 ; static const int nIterations = 10 ; static const int ndm = 2 ; static const int ndf = 2 ; static const int nstress = 3 ; static const int numberNodes = 4 ; static const int numberGauss = 4 ; static const int nShape = 3 ; static const int nEnhanced = 4 ; static const int nModes = 2 ; static const int numberDOF = 8 ; int i, j, k, p, q ; int jj, kk ; int success ; static double xsj[numberGauss] ; // determinant jacaobian matrix static double dvol[numberGauss] ; //volume element static Vector strain(nstress) ; //strain static double shp[nShape][numberNodes] ; //shape functions at a gauss point static double Shape[nShape][numberNodes][numberGauss] ; //all the shape functions static Vector residJ(ndf) ; //nodeJ residual static Matrix stiffJK(ndf,ndf) ; //nodeJK stiffness static Matrix stiffKJ(ndf,ndf) ; //nodeKJ stiffness static Vector stress(nstress) ; //stress static Matrix dd(nstress,nstress) ; //material tangent static Matrix J0(ndm,ndm) ; //Jacobian matrix at center of element static Matrix J0inv(ndm,ndm) ; //inverse of above static Matrix Kee(nEnhanced,nEnhanced) ; static Vector residE(nEnhanced) ; static Vector Umode(ndf) ; static Vector dalpha(nEnhanced) ; static Matrix Kue(numberDOF,nEnhanced) ; static Matrix Keu(nEnhanced,numberDOF) ; static Matrix KeeInvKeu(nEnhanced,numberDOF) ; //---------B-matrices------------------------------------ static Matrix BJ(nstress,ndf) ; // B matrix node J static Matrix BJtran(ndf,nstress) ; static Matrix BK(nstress,ndf) ; // B matrix node k static Matrix BKtran(ndf,nstress) ; static Matrix BJtranD(ndf,nstress) ; //------------------------------------------------------- //zero stiffness and residual stiff.Zero( ) ; resid.Zero( ) ; Kee.Zero( ) ; residE.Zero( ) ; Kue.Zero( ) ; Keu.Zero( ) ; //compute basis vectors and local nodal coordinates computeBasis( ) ; //compute Jacobian and inverse at center double L1 = 0.0 ; double L2 = 0.0 ; computeJacobian( L1, L2, xl, J0, J0inv ) ; //gauss loop to compute and save shape functions double det ; for ( i = 0; i < numberGauss; i++ ) { //get shape functions shape2d( sg[i], tg[i], xl, shp, det ) ; //save shape functions for ( p = 0; p < nShape; p++ ) { for ( q = 0; q < numberNodes; q++ ) Shape[p][q][i] = shp[p][q] ; } // end for p //save jacobian determinant xsj[i] = det ; //volume element to also be saved dvol[i] = wg[i] * det ; } // end for i gauss loop //------------------------------------------------------------------- //newton loop to solve for enhanced strain parameters int count = 0 ; do { residE.Zero( ) ; Kee.Zero( ) ; //gauss loop for ( i = 0; i < numberGauss; i++ ) { //extract shape functions from saved array for ( p = 0; p < nShape; p++ ) { for ( q = 0; q < numberNodes; q++ ) shp[p][q] = Shape[p][q][i] ; } // end for p //zero the strain strain.Zero( ) ; // j-node loop to compute nodal strain contributions for ( j = 0; j < numberNodes; j++ ) { //compute B matrix BJ = computeB( j, shp ) ; //nodal displacements const Vector &ul = nodePointers[j]->getTrialDisp( ) ; //compute the strain strain += (BJ*ul) ; } // end for j // j-node loop to compute enhanced strain contributions for ( j = 0; j < nModes; j++ ) { //compute B matrix BJ = computeBenhanced( j, sg[i], tg[i], xsj[i], J0inv ) ; //enhanced "displacements" Umode(0) = this->alpha( 2*j ) ; Umode(1) = this->alpha( 2*j + 1 ) ; //compute the strain strain += (BJ*Umode) ; } // end for j //send the strain to the material success = materialPointers[i]->setTrialStrain( strain ) ; //compute the stress stress = materialPointers[i]->getStress( ) ; //multiply by volume element stress *= dvol[i] ; //tangent dd = materialPointers[i]->getTangent( ) ; //multiply by volume element dd *= dvol[i] ; //save stress and tangent (already multiplied by volume element) saveData( i, stress, dd ) ; //enhanced residual and tangent calculations loops jj = 0 ; for ( j = 0; j < nModes; j++ ) { //compute B matrix BJ = computeBenhanced( j, sg[i], tg[i], xsj[i], J0inv ) ; //transpose BJtran = transpose( nstress, ndf, BJ ) ; //residual residJ = (BJtran * stress) ; residJ *= (-1.0) ; //residual for ( p = 0; p < ndf; p++ ) residE( jj+p ) += residJ(p) ; BJtranD = BJtran * dd ; kk = 0 ; for ( k = 0; k < nModes; k++ ) { BK = computeBenhanced( k, sg[i], tg[i], xsj[i], J0inv ) ; stiffJK = BJtranD * BK ; for ( p = 0; p < ndf; p++ ) { for ( q = 0; q < ndf; q++ ) Kee( jj+p, kk+q ) += stiffJK( p, q ) ; } //end for p kk += ndf ; } // end for k loop jj += ndf ; } // end for j loop } // end for i gauss loop //cerr << "residE = " << residE << endl ; //solve for enhanced strain parameters dalpha.Zero( ) ; Kee.Solve( residE, dalpha ) ; this->alpha += dalpha ; count++ ; if ( count > nIterations ) { cerr << "Exceeded " << nIterations << " solving for enhanced strain parameters " << endl ; break ; } //end if //do at least 2 iterations so saved data is good } while ( residE.Norm() > tolerance || count < 2 ) ; //cerr << "alpha = " << alpha << endl ; //end enhanced strain parameters newton loop //------------------------------------------------------------------- //gauss loop for ( i = 0; i < numberGauss; i++ ) { //extract shape functions from saved array for ( p = 0; p < nShape; p++ ) { for ( q = 0; q < numberNodes; q++ ) shp[p][q] = Shape[p][q][i] ; } // end for p //recover stress and tangent from saved data getData( i, stress, dd ) ; //residual and tangent calculations node loops jj = 0 ; for ( j = 0; j < numberNodes; j++ ) { BJ = computeB( j, shp ) ; //transpose BJtran = transpose( nstress, ndf, BJ ) ; //residual residJ = BJtran * stress ; for ( p = 0; p < ndf; p++ ) resid( jj+p ) += residJ(p) ; if ( tang_flag == 1 ) { BJtranD = BJtran * dd ; //node-node stiffness kk = 0 ; for ( k = 0; k < numberNodes; k++ ) { BK = computeB( k, shp ) ; stiffJK = BJtranD * BK ; for ( p = 0; p < ndf; p++ ) { for ( q = 0; q < ndf; q++ ) stiff( jj+p, kk+q ) += stiffJK( p, q ) ; } //end for p kk += ndf ; } // end for k loop //node-enhanced stiffness Kue kk = 0 ; for ( k = 0; k < nModes; k++ ) { BK = computeBenhanced( k, sg[i], tg[i], xsj[i], J0inv ) ; stiffJK = BJtranD * BK ; for ( p = 0; p < ndf; p++ ) { for ( q = 0; q < ndf; q++ ) Kue( jj+p, kk+q ) += stiffJK( p, q ) ; } //end for p kk += ndf ; } // end for k loop //enhanced-node stiffness Keu kk = 0 ; for ( k = 0; k < nModes; k++ ) { BK = computeBenhanced( k, sg[i], tg[i], xsj[i], J0inv ) ; //transpose BKtran = transpose( nstress, ndf, BK ) ; stiffKJ = (BKtran*dd)*BJ ; for ( p = 0; p < ndf; p++ ) { for ( q = 0; q < ndf; q++ ) Keu( kk+p, jj+q ) += stiffKJ( p, q ) ; } //end for p kk += ndf ; } // end for k loop } // end if tang_flag jj += ndf ; } // end for j loop } //end for i gauss loop //static condensation of enhanced parameters if ( tang_flag == 1 ) { Kee.Solve( Keu, KeeInvKeu ) ; stiff -= ( Kue * KeeInvKeu ) ; } //end if return ; } //************************************************************************ void EnhancedQuad::saveData( int gp, const Vector &stress, const Matrix &tangent ) { int i, j ; //save stress for ( i=0; i<3; i++ ) stressData[i][gp] = stress(i) ; //save tangent for ( i=0; i<3; i++ ) { for (j=0; j<3; j++ ) tangentData[i][j][gp] = tangent(i,j) ; } //end for i return ; } //************************************************************************ //recover stress and tangent data void EnhancedQuad::getData( int gp, Vector &stress, Matrix &tangent ) { int i, j ; //get stress for ( i=0; i<3; i++ ) stress(i) = stressData[i][gp] ; //get tangent for ( i=0; i<3; i++ ) { for ( j=0; j<3; j++ ) tangent(i,j) = tangentData[i][j][gp] ; } //end for i return ; } //************************************************************************ //compute local coordinates and basis void EnhancedQuad::computeBasis( ) { //nodal coordinates int i ; for ( i = 0; i < 4; i++ ) { const Vector &coorI = nodePointers[i]->getCrds( ) ; xl[0][i] = coorI(0) ; xl[1][i] = coorI(1) ; } //end for i } //************************************************************************* //compute B matrix Matrix EnhancedQuad::computeB( int node, const double shp[3][4] ) { static Matrix B(3,2) ; //---B Matrix in standard {1,2,3} mechanics notation--------------- // // - - // | +N,1 0 | // B = | 0 +N,2 | (3x2) // | +N,2 +N,1 | // - - // //------------------------------------------------------------------- B.Zero( ) ; B(0,0) = shp[0][node] ; B(1,1) = shp[1][node] ; B(2,0) = shp[1][node] ; B(2,1) = shp[0][node] ; return B ; } //*********************************************************************** //compute enhanced strain B-matrices Matrix EnhancedQuad::computeBenhanced( int node, double L1, double L2, double j, const Matrix &Jinv ) { static Matrix B(3,2) ; static Matrix JinvTran(2,2) ; static double shape[2] ; static double parameter ; //compute JinvTran JinvTran(0,0) = Jinv(0,0) ; JinvTran(1,1) = Jinv(1,1) ; JinvTran(0,1) = Jinv(1,0) ; JinvTran(1,0) = Jinv(0,1) ; //residual if ( node == 0 ) { //first column of JinvTran shape[0] = JinvTran(0,0) ; shape[1] = JinvTran(1,0) ; parameter = L1 / j ; } else if ( node == 1 ) { //second column of JinvTran shape[0] = JinvTran(0,1) ; shape[1] = JinvTran(1,1) ; parameter = L2 / j ; } //end if shape[0] *= parameter ; shape[1] *= parameter ; B.Zero( ) ; B(0,0) = shape[0] ; B(1,1) = shape[1] ; B(2,0) = shape[1] ; B(2,1) = shape[0] ; return B ; } //*********************************************************************** //compute Jacobian matrix and inverse at point {L1,L2} void EnhancedQuad::computeJacobian( double L1, double L2, const double x[2][4], Matrix &JJ, Matrix &JJinv ) { int i, j, k ; static const double s[] = { -0.5, 0.5, 0.5, -0.5 } ; static const double t[] = { -0.5, -0.5, 0.5, 0.5 } ; static double shp[2][4] ; double ss = L1 ; double tt = L2 ; for ( i = 0; i < 4; i++ ) { shp[0][i] = s[i] * ( 0.5 + t[i]*tt ) ; shp[1][i] = t[i] * ( 0.5 + s[i]*ss ) ; } // end for i // Construct jacobian and its inverse JJ.Zero( ) ; for ( i = 0; i < 2; i++ ) { for ( j = 0; j < 2; j++ ) { for ( k = 0; k < 4; k++ ) JJ(i,j) += x[i][k] * shp[j][k] ; } //end for j } // end for i double xsj = JJ(0,0)*JJ(1,1) - JJ(0,1)*JJ(1,0) ; //inverse jacobian JJinv(0,0) = JJ(1,1) / xsj ; JJinv(1,1) = JJ(0,0) / xsj ; JJinv(0,1) = -JJ(0,1) / xsj ; JJinv(1,0) = -JJ(1,0) / xsj ; return ; } //************************************************************************ //shape function routine for four node quads void EnhancedQuad::shape2d( double ss, double tt, const double x[2][4], double shp[3][4], double &xsj ) { int i, j, k ; double temp ; static const double s[] = { -0.5, 0.5, 0.5, -0.5 } ; static const double t[] = { -0.5, -0.5, 0.5, 0.5 } ; static Matrix xs(2,2) ; static Matrix sx(2,2) ; for ( i = 0; i < 4; i++ ) { shp[2][i] = ( 0.5 + s[i]*ss )*( 0.5 + t[i]*tt ) ; shp[0][i] = s[i] * ( 0.5 + t[i]*tt ) ; shp[1][i] = t[i] * ( 0.5 + s[i]*ss ) ; } // end for i // Construct jacobian and its inverse xs.Zero( ) ; for ( i = 0; i < 2; i++ ) { for ( j = 0; j < 2; j++ ) { for ( k = 0; k < 4; k++ ) xs(i,j) += x[i][k] * shp[j][k] ; } //end for j } // end for i xsj = xs(0,0)*xs(1,1) - xs(0,1)*xs(1,0) ; //inverse jacobian sx(0,0) = xs(1,1) / xsj ; sx(1,1) = xs(0,0) / xsj ; sx(0,1) = -xs(0,1) / xsj ; sx(1,0) = -xs(1,0) / xsj ; //form global derivatives for ( i = 0; i < 4; i++ ) { temp = shp[0][i]*sx(0,0) + shp[1][i]*sx(1,0) ; shp[1][i] = shp[0][i]*sx(0,1) + shp[1][i]*sx(1,1) ; shp[0][i] = temp ; } // end for i return ; } //********************************************************************** Matrix EnhancedQuad::transpose( int dim1, int dim2, const Matrix &M ) { int i ; int j ; Matrix Mtran( dim2, dim1 ) ; for ( i = 0; i < dim1; i++ ) { for ( j = 0; j < dim2; j++ ) Mtran(j,i) = M(i,j) ; } // end for i return Mtran ; } //********************************************************************** int EnhancedQuad::sendSelf (int commitTag, Channel &theChannel) { return -1; } int EnhancedQuad::recvSelf (int commitTag, Channel &theChannel, FEM_ObjectBroker &theBroker) { return -1; } //************************************************************************** int EnhancedQuad::displaySelf(Renderer &theViewer, int displayMode, float fact) { // first determine the end points of the quad based on // the display factor (a measure of the distorted image) // store this information in 4 3d vectors v1 through v4 const Vector &end1Crd = nodePointers[0]->getCrds(); const Vector &end2Crd = nodePointers[1]->getCrds(); const Vector &end3Crd = nodePointers[2]->getCrds(); const Vector &end4Crd = nodePointers[3]->getCrds(); const Vector &end1Disp = nodePointers[0]->getDisp(); const Vector &end2Disp = nodePointers[1]->getDisp(); const Vector &end3Disp = nodePointers[2]->getDisp(); const Vector &end4Disp = nodePointers[3]->getDisp(); static Matrix coords(4,3) ; static Vector values(4) ; static Vector P(8) ; coords.Zero( ) ; values(0) = 1 ; values(1) = 1 ; values(2) = 1 ; values(3) = 1 ; if (displayMode < 3 && displayMode > 0) P = this->getResistingForce(); for (int i = 0; i < 2; i++) { coords(0,i) = end1Crd(i) + end1Disp(i)*fact; coords(1,i) = end2Crd(i) + end2Disp(i)*fact; coords(2,i) = end3Crd(i) + end3Disp(i)*fact; coords(3,i) = end4Crd(i) + end4Disp(i)*fact; /* if (displayMode < 3 && displayMode > 0) values(i) = P(displayMode*2+i); else values(i) = 1; */ } //cerr << coords; int error = 0; error += theViewer.drawPolygon (coords, values); return error; } //*************************************************************************** /* //zero the strains strain.Zero( ) ; // j-node loop to compute strain for ( j = 0; j < numberNodes; j++ ) { //compute B matrix BJ = computeB( j, shp ) ; //nodal displacements const Vector &ul = nodePointers[j]->getTrialDisp( ) ; //compute the strain strain += (BJ*ul) ; } // end for j // j-node loop to compute enhanced strain contributions for ( j = 0; j < nModes; j++ ) { //compute B matrix BJ = computeBenhanced( j, sg[i], tg[i], xsj[i], J0inv ) ; //enhanced "displacements" Umode(0) = this->alpha( 2*j ) ; Umode(1) = this->alpha( 2*j + 1 ) ; //compute the strain strain += (BJ*Umode) ; } // end for j //send the strain to the material success = materialPointers[i]->setTrialStrain( strain ) ; //compute the stress stress = materialPointers[i]->getStress( ) ; //multiply by volume element stress *= dvol[i] ; if ( tang_flag == 1 ) { dd = materialPointers[i]->getTangent( ) ; dd *= dvol[i] ; } //end if tang_flag */

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