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32 lines
689 B
32 lines
689 B
3 years ago
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function f = elastic_force_nonregular(F, gradN, nodeNum, edofMat, lx, u, l)
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f = sparse(nodeNum*2, 1);
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jac = lx^2/4;
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for ele = 1:size(edofMat, 1)
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fe = zeros(2, 4);
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% element stiffness
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for gp = 1:4
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Fe = F{gp, ele};
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Pe = PK1(u, l, Fe);
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Be = gradN{gp};
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fe = fe + Pe * Be' * jac;
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end
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edof = edofMat(ele, :);
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f(edof) = f(edof) - fe(:); % NOTE: MINUS!
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end
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end
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function PP = PK1(u,l,F)
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% Neo hookean
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JJ = log(det(F));
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Finv = inv(F)';
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PP = u*(F-Finv) + l*JJ*Finv;
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% Linear
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% I = eye(3,3);
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% PP = u*(F + F'-2*I) + l * (trace(F)-3) * I;
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end
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