%%%%%%%%%%%  一阶六面体单元线弹性材料应力-应变矩阵   %%%%%%%%%%%
%  D线弹性材料应力-应变矩阵
%  E弹性模量  
%  u泊松比
function [D]=LinearIsotropicD(E,u) 
D=E/((1+u)*(1-2*u))*[1-u u u 0 0 0;u 1-u u 0 0 0;u u 1-u 0 0 0;0 0 0 (1-2*u)/2 0 0;0 0 0 0 (1-2*u)/2 0;0 0 0 0 0 (1-2*u)/2];
end