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ArcLength.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: 1.7 $ // $Date: 2005/10/19 21:53:57 $ // $Source: /usr/local/cvs/OpenSees/SRC/analysis/integrator/ArcLength.cpp,v $ // File: ~/analysis/integrator/ArcLength.C // // Written: fmk // Created: 07/98 // Revision: A // // Description: This file contains the class definition for ArcLength. // ArcLength is an algorithmic class for perfroming a static analysis // using the arc length scheme, that is within a load step the follwing // constraint is enforced: dU^TdU + alpha^2*dLambda^2 = arcLength^2 // where dU is change in nodal displacements for step, dLambda is // change in applied load and arcLength is a control parameter. // // What: "@(#) ArcLength.C, revA" #include <ArcLength.h> #include <AnalysisModel.h> #include <LinearSOE.h> #include <Vector.h> #include <Channel.h> #include <math.h> ArcLength::ArcLength(double arcLength, double alpha) :StaticIntegrator(INTEGRATOR_TAGS_ArcLength), arcLength2(arcLength*arcLength), alpha2(alpha*alpha), deltaUhat(0), deltaUbar(0), deltaU(0), deltaUstep(0), phat(0), deltaLambdaStep(0.0), currentLambda(0.0), signLastDeltaLambdaStep(1) { } ArcLength::~ArcLength() { // delete any vector object created if (deltaUhat != 0) delete deltaUhat; if (deltaU != 0) delete deltaU; if (deltaUstep != 0) delete deltaUstep; if (deltaUbar != 0) delete deltaUbar; if (phat != 0) delete phat; } int ArcLength::newStep(void) { // get pointers to AnalysisModel and LinearSOE AnalysisModel *theModel = this->getAnalysisModelPtr(); LinearSOE *theLinSOE = this->getLinearSOEPtr(); if (theModel == 0 || theLinSOE == 0) { opserr << "WARNING ArcLength::newStep() "; opserr << "No AnalysisModel or LinearSOE has been set\n"; return -1; } // get the current load factor currentLambda = theModel->getCurrentDomainTime(); if (deltaLambdaStep < 0) signLastDeltaLambdaStep = -1; else signLastDeltaLambdaStep = +1; // determine dUhat this->formTangent(); theLinSOE->setB(*phat); if (theLinSOE->solve() < 0) { opserr << "ArcLength::newStep(void) - failed in solver\n"; return -1; } (*deltaUhat) = theLinSOE->getX(); Vector &dUhat = *deltaUhat; // determine delta lambda(1) == dlambda double dLambda = sqrt(arcLength2/((dUhat^dUhat)+alpha2)); dLambda *= signLastDeltaLambdaStep; // base sign of load change // on what was happening last step deltaLambdaStep = dLambda; currentLambda += dLambda; // determine delta U(1) == dU (*deltaU) = dUhat; (*deltaU) *= dLambda; (*deltaUstep) = (*deltaU); // update model with delta lambda and delta U theModel->incrDisp(*deltaU); theModel->applyLoadDomain(currentLambda); theModel->updateDomain(); return 0; } int ArcLength::update(const Vector &dU) { AnalysisModel *theModel = this->getAnalysisModelPtr(); LinearSOE *theLinSOE = this->getLinearSOEPtr(); if (theModel == 0 || theLinSOE == 0) { opserr << "WARNING ArcLength::update() "; opserr << "No AnalysisModel or LinearSOE has been set\n"; return -1; } (*deltaUbar) = dU; // have to do this as the SOE is gonna change // determine dUhat theLinSOE->setB(*phat); theLinSOE->solve(); (*deltaUhat) = theLinSOE->getX(); // determine the coeeficients of our quadratic equation double a = alpha2 + ((*deltaUhat)^(*deltaUhat)); double b = alpha2*deltaLambdaStep + ((*deltaUhat)^(*deltaUbar)) + ((*deltaUstep)^(*deltaUhat)); b *= 2.0; double c = 2*((*deltaUstep)^(*deltaUbar)) + ((*deltaUbar)^(*deltaUbar)); // check for a solution to quadratic double b24ac = b*b - 4.0*a*c; if (b24ac < 0) { opserr << "ArcLength::update() - imaginary roots due to multiple instability"; opserr << " directions - initial load increment was too large\n"; opserr << "a: " << a << " b: " << b << " c: " << c << " b24ac: " << b24ac << endln; return -1; } double a2 = 2.0*a; if (a2 == 0.0) { opserr << "ArcLength::update() - zero denominator"; opserr << " alpha was set to 0.0 and zero reference load\n"; return -2; } // determine the roots of the quadratic double sqrtb24ac = sqrt(b24ac); double dlambda1 = (-b + sqrtb24ac)/a2; double dlambda2 = (-b - sqrtb24ac)/a2; double val = (*deltaUhat)^(*deltaUstep); double theta1 = ((*deltaUstep)^(*deltaUstep)) + ((*deltaUbar)^(*deltaUstep)); // double theta2 = theta1 + dlambda2*val; theta1 += dlambda1*val; // choose dLambda based on angle between incremental displacement before // and after this step -- want positive double dLambda; if (theta1 > 0) dLambda = dlambda1; else dLambda = dlambda2; // determine delta U(i) (*deltaU) = (*deltaUbar); deltaU->addVector(1.0, *deltaUhat,dLambda); // update dU and dlambda (*deltaUstep) += *deltaU; deltaLambdaStep += dLambda; currentLambda += dLambda; // update the model theModel->incrDisp(*deltaU); theModel->applyLoadDomain(currentLambda); theModel->updateDomain(); // set the X soln in linearSOE to be deltaU for convergence Test theLinSOE->setX(*deltaU); return 0; } int ArcLength::domainChanged(void) { // we first create the Vectors needed AnalysisModel *theModel = this->getAnalysisModelPtr(); LinearSOE *theLinSOE = this->getLinearSOEPtr(); if (theModel == 0 || theLinSOE == 0) { opserr << "WARNING ArcLength::update() "; opserr << "No AnalysisModel or LinearSOE has been set\n"; return -1; } int size = theModel->getNumEqn(); // ask model in case N+1 space if (deltaUhat == 0 || deltaUhat->Size() != size) { // create new Vector if (deltaUhat != 0) delete deltaUhat; // delete the old deltaUhat = new Vector(size); if (deltaUhat == 0 || deltaUhat->Size() != size) { // check got it opserr << "FATAL ArcLength::domainChanged() - ran out of memory for"; opserr << " deltaUhat Vector of size " << size << endln; exit(-1); } } if (deltaUbar == 0 || deltaUbar->Size() != size) { // create new Vector if (deltaUbar != 0) delete deltaUbar; // delete the old deltaUbar = new Vector(size); if (deltaUbar == 0 || deltaUbar->Size() != size) { // check got it opserr << "FATAL ArcLength::domainChanged() - ran out of memory for"; opserr << " deltaUbar Vector of size " << size << endln; exit(-1); } } if (deltaU == 0 || deltaU->Size() != size) { // create new Vector if (deltaU != 0) delete deltaU; // delete the old deltaU = new Vector(size); if (deltaU == 0 || deltaU->Size() != size) { // check got it opserr << "FATAL ArcLength::domainChanged() - ran out of memory for"; opserr << " deltaU Vector of size " << size << endln; exit(-1); } } if (deltaUstep == 0 || deltaUstep->Size() != size) { if (deltaUstep != 0) delete deltaUstep; deltaUstep = new Vector(size); if (deltaUstep == 0 || deltaUstep->Size() != size) { opserr << "FATAL ArcLength::domainChanged() - ran out of memory for"; opserr << " deltaUstep Vector of size " << size << endln; exit(-1); } } if (phat == 0 || phat->Size() != size) { if (phat != 0) delete phat; phat = new Vector(size); if (phat == 0 || phat->Size() != size) { opserr << "FATAL ArcLength::domainChanged() - ran out of memory for"; opserr << " phat Vector of size " << size << endln; exit(-1); } } // now we have to determine phat // do this by incrementing lambda by 1, applying load // and getting phat from unbalance. currentLambda = theModel->getCurrentDomainTime(); currentLambda += 1.0; theModel->applyLoadDomain(currentLambda); this->formUnbalance(); // NOTE: this assumes unbalance at last was 0 (*phat) = theLinSOE->getB(); currentLambda -= 1.0; theModel->setCurrentDomainTime(currentLambda); // check there is a reference load int haveLoad = 0; for (int i=0; i<size; i++) if ( (*phat)(i) != 0.0 ) { haveLoad = 1; i = size; } if (haveLoad == 0) { opserr << "WARNING ArcLength::domainChanged() - zero reference load"; return -1; } return 0; } int ArcLength::sendSelf(int cTag, Channel &theChannel) { Vector data(5); data(0) = arcLength2; data(1) = alpha2; data(2) = deltaLambdaStep; data(3) = currentLambda; data(4) = signLastDeltaLambdaStep; if (theChannel.sendVector(this->getDbTag(), cTag, data) < 0) { opserr << "ArcLength::sendSelf() - failed to send the data\n"; return -1; } return 0; } int ArcLength::recvSelf(int cTag, Channel &theChannel, FEM_ObjectBroker &theBroker) { Vector data(5); if (theChannel.recvVector(this->getDbTag(), cTag, data) < 0) { opserr << "ArcLength::sendSelf() - failed to send the data\n"; return -1; } // set the data arcLength2 = data(0); alpha2 = data(1); deltaLambdaStep = data(2); currentLambda = data(3); signLastDeltaLambdaStep = data(4); return 0; } void ArcLength::Print(OPS_Stream &s, int flag) { AnalysisModel *theModel = this->getAnalysisModelPtr(); if (theModel != 0) { double cLambda = theModel->getCurrentDomainTime(); s << "\t ArcLength - currentLambda: " << cLambda; s << " arcLength: " << sqrt(arcLength2) << " alpha: "; s << sqrt(alpha2) << endln; } else s << "\t ArcLength - no associated AnalysisModel\n"; } Generated on Mon Oct 23 15:04:58 2006 for OpenSees by  1.5.0

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