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50 lines
1.6 KiB
50 lines
1.6 KiB
11 months ago
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%%%%%%%%%% 3D FEM with brick element %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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function [U]=FEM_Beam(nx,ny,nz,ke_all)
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N = 3*(nx+1)*(ny+1)*(nz+1);
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% K = sparse(N, N);
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nele=nx*ny*nz;
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si=zeros(1,nele*24^2);
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sj=zeros(1,nele*24^2);
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sv=zeros(1,nele*24^2);
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for elx = 1:nx
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for ely = 1:ny
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for elz = 1:nz
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% n1 = (nz+1)*(ny+1)*elx + (nz+1)*(ely-1) + elz;
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% n2 = n1 - (nz+1)*(ny+1);
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n2 = (nz+1)*(ny+1)*elx + (nz+1)*(ely-1) + elz;
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n1 = n2-(nz+1)*(ny+1);
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n3 = n1 + (nz+1);
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n4 = n2 + (nz+1);
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n5 = n1 + 1;
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n6 = n2 + 1;
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n7 = n3 + 1;
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n8 = n4 + 1;
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edof = [3*n1-2; 3*n1-1; 3*n1;
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3*n2-2; 3*n2-1; 3*n2;
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3*n3-2; 3*n3-1; 3*n3;
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3*n4-2; 3*n4-1; 3*n4;
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3*n5-2; 3*n5-1; 3*n5;
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3*n6-2; 3*n6-1; 3*n6;
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3*n7-2; 3*n7-1; 3*n7;
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3*n8-2; 3*n8-1; 3*n8];
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ne=(elx-1)*ny*nz+(ely-1)*nz+elz;
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si((ne-1)*24^2+1:ne*24^2)=kron(ones(1,24),edof.');
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sj((ne-1)*24^2+1:ne*24^2)=kron(edof.',ones(1,24));
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ke=ke_all(:,:,elz,ely,elx);
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sv((ne-1)*24^2+1:ne*24^2)=ke(:);
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% K(edof,edof) = K(edof,edof) + ke_all(:,:,elz,ely,elx);
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end
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end
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end
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K = sparse(si,sj,sv,N,N);
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loadnodes=nx*(ny+1)*(nz+1)+1:nz+1:(nx+1)*(ny+1)*(nz+1)-nz;
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loaddofs = loadnodes(:).*3;
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F = zeros(N,1); F(loaddofs) = -1;
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fixeddofs = [1:3*(ny+1)*(nz+1)];
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alldofs = [1:N];
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freedofs = setdiff(alldofs,fixeddofs);
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U = zeros(N,1);
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U(freedofs,:) = K(freedofs,freedofs) \ F(freedofs,:);
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end
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