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00001 /* ****************************************************************** **
00002 **    OpenSees - Open System for Earthquake Engineering Simulation    **
00003 **          Pacific Earthquake Engineering Research Center            **
00004 **                                                                    **
00005 **                                                                    **
00006 ** (C) Copyright 1999, The Regents of the University of California    **
00007 ** All Rights Reserved.                                               **
00008 **                                                                    **
00009 ** Commercial use of this program without express permission of the   **
00010 ** University of California, Berkeley, is strictly prohibited.  See   **
00011 ** file 'COPYRIGHT'  in main directory for information on usage and   **
00012 ** redistribution,  and for a DISCLAIMER OF ALL WARRANTIES.           **
00013 **                                                                    **
00014 ** Developed by:                                                      **
00015 **   Frank McKenna (fmckenna@ce.berkeley.edu)                         **
00016 **   Gregory L. Fenves (fenves@ce.berkeley.edu)                       **
00017 **   Filip C. Filippou (filippou@ce.berkeley.edu)                     **
00018 **                                                                    **
00019 ** ****************************************************************** */
00020                                                                         
00021 // $Revision: 1.2 $
00022 // $Date: 2001/07/11 18:22:53 $
00023 // $Source: /usr/local/cvs/OpenSees/SRC/material/uniaxial/ViscousMaterial.cpp,v $
00024                                                                         
00025 // Written: Mehrdad Sasani 
00026 // Created: June 2000
00027 // Revision: A
00028 //
00029 // Description: This file contains the class implementation for 
00030 // ViscousMaterial. 
00031 
00032 #include <ViscousMaterial.h>
00033 #include <Vector.h>
00034 #include <Channel.h>
00035 
00036 ViscousMaterial::ViscousMaterial(int tag, double c, double a)
00037 :UniaxialMaterial(tag,MAT_TAG_Viscous),
00038  trialRate(0.0), C(c), Alpha(a)
00039 {
00040     if (Alpha < 0.0) {
00041         g3ErrorHandler->warning("%s -- Alpha < 0.0, setting to 1.0",
00042             "ViscousMaterial::ViscousMaterial");
00043         Alpha = 1.0;
00044     }
00045 }
00046 
00047 ViscousMaterial::ViscousMaterial()
00048 :UniaxialMaterial(0,MAT_TAG_Viscous),
00049  trialRate(0.0), C(0.0), Alpha(0.0)
00050 {
00051 
00052 }
00053 
00054 ViscousMaterial::~ViscousMaterial()
00055 {
00056   // does nothing
00057 }
00058 
00059 int 
00060 ViscousMaterial::setTrialStrain(double strain, double strainRate)
00061 {
00062     trialRate = strainRate;
00063 
00064     return 0;
00065 }
00066 
00067 double 
00068 ViscousMaterial::getStress(void)
00069 {
00070     double stress = C*pow(fabs(trialRate),Alpha);
00071 
00072     if (trialRate < 0.0)
00073         return -stress;
00074     else
00075         return  stress;
00076 }
00077 
00078 double 
00079 ViscousMaterial::getTangent(void)
00080 {
00081     return 0.0;
00082 }
00083 
00084 double
00085 ViscousMaterial::getDampTangent(void)
00086 {
00087  static const double minvel = 1.e-11;
00088 
00089     double absRate = fabs(trialRate);
00090 
00091     if (absRate < minvel)
00092   return Alpha*C*pow(minvel,Alpha-1.0);
00093  else
00094   return Alpha*C*pow(absRate,Alpha-1.0); 
00095 }
00096 
00097 double 
00098 ViscousMaterial::getSecant(void)
00099 {
00100     return 0.0;
00101 }
00102 
00103 double 
00104 ViscousMaterial::getStrain(void)
00105 {
00106     return 0.0;
00107 }
00108 
00109 double 
00110 ViscousMaterial::getStrainRate(void)
00111 {
00112     return trialRate;
00113 }
00114 
00115 int 
00116 ViscousMaterial::commitState(void)
00117 {
00118     return 0;
00119 }
00120 
00121 int 
00122 ViscousMaterial::revertToLastCommit(void)
00123 {
00124     return 0;
00125 }
00126 
00127 int 
00128 ViscousMaterial::revertToStart(void)
00129 {
00130     trialRate = 0.0;
00131 
00132     return 0;
00133 }
00134 
00135 UniaxialMaterial *
00136 ViscousMaterial::getCopy(void)
00137 {
00138     ViscousMaterial *theCopy = new ViscousMaterial(this->getTag(),C,Alpha);
00139 
00140     theCopy->trialRate = trialRate;
00141 
00142     return theCopy;
00143 }
00144 
00145 int 
00146 ViscousMaterial::sendSelf(int cTag, Channel &theChannel)
00147 {
00148   int res = 0;
00149   static Vector data(4);
00150   data(0) = this->getTag();
00151   data(1) = C;
00152   data(2) = Alpha;
00153   data(3) = trialRate;
00154   res = theChannel.sendVector(this->getDbTag(), cTag, data);
00155   if (res < 0) 
00156     cerr << "ViscousMaterial::sendSelf() - failed to send data\n";
00157 
00158   return res;
00159 }
00160 
00161 int 
00162 ViscousMaterial::recvSelf(int cTag, Channel &theChannel, 
00163           FEM_ObjectBroker &theBroker)
00164 {
00165   int res = 0;
00166   static Vector data(4);
00167   res = theChannel.recvVector(this->getDbTag(), cTag, data);
00168   
00169   if (res < 0) {
00170       cerr << "ViscousMaterial::recvSelf() - failed to receive data\n";
00171       C = 0; 
00172       this->setTag(0);      
00173   }
00174   else {
00175     this->setTag((int)data(0));
00176     C = data(1);
00177  Alpha = data(2);
00178     trialRate = data(3);
00179   }
00180     
00181   return res;
00182 }
00183 
00184 void 
00185 ViscousMaterial::Print(ostream &s, int flag)
00186 {
00187     s << "Viscous tag: " << this->getTag() << endl;
00188     s << "  C: " << C << endl;
00189     s << "  Alpha: " << Alpha << endl;
00190 }
00191 
00192