norshell4.f File Reference

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Functions/Subroutines
subroutine	norshell4 (xi, et, xl, xnor)

Function/Subroutine Documentation

norshell4()

subroutine norshell4	(	real*8	xi,
		real*8	et,
		real*8, dimension(3,8)	xl,
		real*8, dimension(3)	xnor
	)

!
!     calculates the normal on a quadratic shell element in a point
!     with local coordinates xi and et. The coordinates of the nodes
!     belonging to the element are stored in xl
!
      implicit none
!
      integer i,j,k
!
      real*8 shp(7,4),xs(3,7),xl(3,8),sh(3),xnor(3)
!
      real*8 xi,et
!
!     shape functions and their glocal derivatives for an element
!     described with two local parameters and three global ones.
!
!     local derivatives of the shape functions: xi-derivative
!      
      shp(1,1)=-(1.d0-et)/4.d0
      shp(1,2)=(1.d0-et)/4.d0
      shp(1,3)=(1.d0+et)/4.d0
      shp(1,4)=-(1.d0+et)/4.d0
!
!     local derivatives of the shape functions: eta-derivative
!
      shp(2,1)=-(1.d0-xi)/4.d0
      shp(2,2)=-(1.d0+xi)/4.d0
      shp(2,3)=(1.d0+xi)/4.d0
      shp(2,4)=(1.d0-xi)/4.d0
!
!     computation of the local derivative of the global coordinates
!     (xs)
!
      do i=1,3
        do j=1,2
          xs(i,j)=0.d0
          do k=1,4
            xs(i,j)=xs(i,j)+xl(i,k)*shp(j,k)
          enddo
        enddo
      enddo
!
!     computation of the jacobian vector
!
      xnor(1)=xs(2,1)*xs(3,2)-xs(3,1)*xs(2,2)
      xnor(2)=xs(1,2)*xs(3,1)-xs(3,2)*xs(1,1)
      xnor(3)=xs(1,1)*xs(2,2)-xs(2,1)*xs(1,2)
!
      return