Method formResidAndTangent

SRC/element/shell/ShellMITC4.cpp:1328–1757

form residual and tangent

//form residual and tangent
void  
ShellMITC4::formResidAndTangent( int tang_flag ) 
{
  //
  //  six(6) nodal dof's ordered :
  //
  //    -        - 
  //   |    u1    |   <---plate membrane
  //   |    u2    |
  //   |----------|
  //   |  w = u3  |   <---plate bending
  //   |  theta1  | 
  //   |  theta2  | 
  //   |----------|
  //   |  theta3  |   <---drill 
  //    -        -  
  //
  // membrane strains ordered :
  //
  //            strain(0) =   eps00     i.e.   (11)-strain
  //            strain(1) =   eps11     i.e.   (22)-strain
  //            strain(2) =   gamma01   i.e.   (12)-shear
  //
  // curvatures and shear strains ordered  :
  //
  //            strain(3) =     kappa00  i.e.   (11)-curvature
  //            strain(4) =     kappa11  i.e.   (22)-curvature
  //            strain(5) =   2*kappa01  i.e. 2*(12)-curvature 
  //
  //            strain(6) =     gamma02  i.e.   (13)-shear
  //            strain(7) =     gamma12  i.e.   (23)-shear
  //
  //  same ordering for moments/shears but no 2 
  //  
  //  Then, 
  //              epsilon00 = -z * kappa00      +    eps00_membrane
  //              epsilon11 = -z * kappa11      +    eps11_membrane
  //  gamma01 = 2*epsilon01 = -z * (2*kappa01)  +  gamma01_membrane 
  //
  //  Shear strains gamma02, gamma12 constant through cross section
  //

  static const int ndf = 6 ; //two membrane plus three bending plus one drill

  static const int nstress = 8 ; //three membrane, three moment, two shear

  static const int ngauss = 4 ;

  static const int numnodes = 4 ;

  int i,  j,  k, p, q ;
  int jj, kk ;

  int success ;
  
  double volume = 0.0 ;

  static double xsj ;  // determinant jacaobian matrix