1! 2! CalculiX - A 3-dimensional finite element program 3! Copyright (C) 1998-2021 Guido Dhondt 4! 5! This program is free software; you can redistribute it and/or 6! modify it under the terms of the GNU General Public License as 7! published by the Free Software Foundation(version 2); 8! 9! 10! This program is distributed in the hope that it will be useful, 11! but WITHOUT ANY WARRANTY; without even the implied warranty of 12! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13! GNU General Public License for more details. 14! 15! You should have received a copy of the GNU General Public License 16! along with this program; if not, write to the Free Software 17! Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 18! 19 subroutine hgstiffness(s,elas,a,gs) 20! 21! hourglass control stiffness for 8-node solid mean strain element 22! 23! Reference: Flanagan, D.P., Belytschko, T.; "Uniform strain hexahedron 24! and quadrilateral with orthogonal Hourglass control". Int. J. Num. 25! Meth. Engg., Vol. 17, 679-706, 1981. 26! 27! author: Otto-Ernst Bernhardi 28! 29 implicit none 30! 31 integer ii1,jj1,ii,jj,m1 32! 33 real*8 s(60,60),gs(8,4),a,elas(1),hgls,ahr 34! 35! 36! 37 ahr=elas(1)*a 38c write(6,*) "stiffness:", ahr 39! 40 jj1=1 41 do jj=1,8 42 ii1=1 43 do ii=1,jj 44 hgls=0.0d0 45 do m1=1,4 46 hgls=hgls+gs(jj,m1)*gs(ii,m1) 47 enddo 48 hgls=hgls*ahr 49 s(ii1,jj1)=s(ii1,jj1)+hgls 50 s(ii1+1,jj1+1)=s(ii1+1,jj1+1)+hgls 51 s(ii1+2,jj1+2)=s(ii1+2,jj1+2)+hgls 52 ii1=ii1+3 53 enddo 54 jj1=jj1+3 55 enddo 56 return 57 end 58