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1、例题:如图所示的受力均匀分布载荷作用的薄平板结构,将平板离散成两个线性三角元,如图所示,假定。求(1)该结构的整体刚度矩阵。(2)节点2和节点3的水平位移和垂直位移。(3)节点1和节点4的支反力。(4)每个单元的应力。(5)每个单元的主应力和主应力方向角。图1.薄平板结构图2.用双线性三角元离散化的薄木板解:(1)离散化域我们将平板分为两个单元,4个节点,如图2所示,分布载荷的总作用力平均分给节点2和节点3,由于结构是薄平板,所以假定其属于平面应力情况。MATLAB中采用的计算单位是KN和m。表1给出了该题的单元连通性。表1该题的单元连通性单元编号节点i节点j节点m113
2、42123(2)单元刚度矩阵通过调用MATLAB的LinearTriangleElementStiffness函数,得到两个单元矩阵k1和k2,每个矩阵都是的。k1=gangdujuzhen(@LinearTriangleElementStiffness,210000000,0.3,0.025,0,0,0.5,0.25,0,0.25,1)的源程序:functionk1=gangdujuzhen(f,E,NU,t,xi,yi,xj,yj,xm,ym,p)%UNTITLED4此处显示有关此函数的摘要%此处显示详细说明k1=gangdujuzhen(@LinearTriangl
3、eElementStiffness,210000000,0.3,0.025,0,0,0.5,0.25,0,0.25,1)k1=f(E,NU,t,xi,yi,xj,yj,xm,ym,p);>>k1=gangdujuzhen(@LinearTriangleElementStiffness,210000000,0.3,0.025,0,0,0.5,0.25,0,0.25,1)k1=1.0e+06*2.019200-1.0096-2.01921.009605.7692-0.865400.8654-5.76920-0.86541.44230-1.44230.8654-1.009600
4、0.50481.0096-0.5048-2.01920.8654-1.44231.00963.4615-1.87501.0096-5.76920.8654-0.5048-1.87506.2740k2=gangdujuzhen2(@LinearTriangleElementStiffness,210000000,0.3,0.025,0,0,0.5,0,0.5,0.25,1)的源程序:functionk2=gangdujuzhen2(f,E,NU,t,xi,yi,xj,yj,xm,ym,p)%UNTITLED3此处显示有关此函数的摘要%此处显示详细说明k2=gangdujuz
5、hen2(@LinearTriangleElementStiffness,210000000,0.3,0.025,0,0,0.5,0,0.5,0.25,1)k2=f(E,NU,t,xi,yi,xj,yj,xm,ym,p);>>k2=gangdujuzhen2(@LinearTriangleElementStiffness,210000000,0.3,0.025,0,0,0.5,0,0.5,0.25,1)k2=1.0e+06*1.44230-1.44230.86540-0.865400.50481.0096-0.5048-1.00960-1.44231.00963.4615
6、-1.8750-2.01920.86540.8654-0.5048-1.87506.27401.0096-5.76920-1.0096-2.01921.00962.01920-0.865400.8654-5.769205.7692(3)集成整体刚度矩阵由于结构有4个节点,所以刚度矩阵是的,因此为了得到整体刚度矩阵K,我们首先要生成一个的零矩阵。由于在这个系统中有两个线性三角元,所以两次调用MATLAB的LinearTriangleAssemble函数就可以得到整体刚度矩阵K。每次对该函数的调用都会集成一个单元。K=zero(8,8)的源程序:functionK=zero(
7、x,y)%UNTITLED4此处显示有关此函数的摘要%此处显示详细说明K=zero(8,8)K=zeros(x,y);>>K=zero(8,8)K=0000000000000000000000000000000000000000000000000000000000000000K1=gdfuhe1(@LinearTriangleAssemble,K,k1,1,3,4)的源程序:functionK1=gdfuhe1(f,K,k,i,j,m)%UNTITLED此处显示有关此函数的摘要%此处显示详细说明K1=gdfuhe1(@Line