27 lines
1.2 KiB
Mathematica
27 lines
1.2 KiB
Mathematica
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function ke=ele_stiff_matrix(E_ID,Nodes,Elements,E,u,Width)
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ENodes(:,1) = Elements(E_ID,:);
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iN = size(ENodes,1);
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ke = zeros(2*iN,2*iN);
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D=[E/(1-u^2),u*E/(1-u^2),0;
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u*E/(1-u^2),E/(1-u^2),0;
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0,0,E/(2*(1+u))];
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% <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>˹<EFBFBD><EFBFBD><EFBFBD>ֵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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kesi_yita=[-1/sqrt(3),-1/sqrt(3);1/sqrt(3),-1/sqrt(3);1/sqrt(3),1/sqrt(3);-1/sqrt(3),1/sqrt(3)];
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w=[1,1];ww=[w(1)*w(1),w(2)*w(1),w(1)*w(1),w(1)*w(2)];
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% <EFBFBD><EFBFBD>˹<EFBFBD><EFBFBD><EFBFBD>ּ<EFBFBD><EFBFBD>㵥Ԫ<EFBFBD>նȾ<EFBFBD><EFBFBD><EFBFBD>
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for i=1:4
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kesi=kesi_yita(i,1);yita=kesi_yita(i,2); %提取形函数对kesi（或yita）的偏导<EFBFBD><EFBFBD>?
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J = Jacobi(E_ID,kesi,yita,Elements,Nodes); % <EFBFBD>ſɱȾ<EFBFBD><EFBFBD><EFBFBD>
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% J=Q4_J(kesi,yita,xy); %计算J矩阵
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A=1/det(J)*[ J(2,2),-J(1,2), 0, 0;
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0, 0,-J(2,1), J(1,1);
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-J(2,1), J(1,1), J(2,2),-J(1,2)]; %根据J矩阵计算A矩阵
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G=Q4_G(kesi,yita); %根据偏导值计算G矩阵
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B=A*G; %根据A和G计算应变矩阵B（高斯积分点处的应变矩阵B<EFBFBD><EFBFBD>?
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ke=ke+ww(i)*B'*D*B*Width*det(J);
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end
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end
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