bilinem.m

有限元平面问题的求解相关程序。 包括质量矩阵

function M=bilineM(a,b,density)%质量矩阵子函数
%求质量矩阵
I=zeros(8,8);
syms x y;
xia=[(1-x)*(1-y)/4; (1+x)*(1-y)/4; (1+x)*(1+y)/4; (1-x)*(1+y)/4];
I=xia*transpose(xia);
for i=1:4;
    for j=1:4;
        Iff(i,j)=int(int(I(i,j),x,-1,1),y,-1,1);
    end
end
M2=double((density*a*b/4)*Iff);
M1=zeros(8,8);
M1(1:4,1:4)=M2(:,:);
M1(5:8,5:8)=M2(:,:);
M2=[M1(1:1,1:8);
   M1(5:5,1:8);
   M1(2:2,1:8);
   M1(6:6,1:8);
   M1(3:3,1:8);
   M1(7:7,1:8);
   M1(4:4,1:8);
   M1(8:8,1:8)];
M=[M2(1:8,1:1),M2(1:8,5:5),M2(1:8,2:2),M2(1:8,6:6),M2(1:8,3:3),M2(1:8,7:7),M2(1:8,4:4),M2(1:8,8:8)];