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44 lines
1.3 KiB
44 lines
1.3 KiB
%--------------------------
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% @Author: Jingqiao Hu
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% @Date: 2021-02-22 13:20:56
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% @LastEditTime: 2021-11-28 13:49:03
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%--------------------------
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function K = multi_stiffness_linear2(dFdx, iK, jK, dx, global_u, global_l, lenout, D1, rho_cell)
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eleNum = size(dFdx, 2);
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jac = dx^2/4;
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sK = zeros(lenout^2, eleNum);
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for ele_ma = 1:eleNum
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% tic
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u = global_u{ele_ma};
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l = global_l{ele_ma};
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rho_e = rho_cell{ele_ma}(:); % m,1
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tmp = speye(length(rho_e)) .* rho_e; % m,m
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D = kron(tmp, D1);
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% element stiffness
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ke = 0;
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for gp = 1:4
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dFe = dFdx{gp, ele_ma}; % 4 * lenout * eleNum_mi
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dP1 = dPdF_fast_linear(u, l, dFe); % 4 * l * m
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dPT = permute(dP1, [2,1,3]); % l * 4 * m
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dP2 = reshape(dPT, lenout, []); % l * 4m
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dF1 = permute(dFe, [2,1,3]); % l * 4 * eleNum_mi
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dF2 = reshape(dF1, lenout, [])'; % 4m * l
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%
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% ke_g = dF2' * D * dF2; % lenout * lenout
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ke_g = dP2 * dF2; % lenout * lenout
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ke = ke + ke_g * jac;
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end
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% toc
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sK(:, ele_ma) = ke(:);
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end
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K = sparse(iK, jK, sK);
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K = (K + K')/2;
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end
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