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34 lines
1.1 KiB
34 lines
1.1 KiB
4 years ago
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% periodic boundary conditions
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function [wfixed,ufixed,d1,d2,d3,d4,testNum] = microPBC(nelx,nely,lx,ly)
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nodenrs = reshape(1:(1 + nelx) * (1 + nely), 1 + nely, 1 + nelx);
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e0 = eye(3);
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ufixed = zeros(8, 3);
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alldofs = 1:2 * (nely + 1) * (nelx + 1);
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% four corner points
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n1 = [nodenrs(end, [1, end]), nodenrs(1, [end, 1])];
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d1 = reshape([2 * n1 - 1; 2 * n1], 1, 8);
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% left+bottom boundaries
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n3 = [nodenrs(2:end - 1, 1)', nodenrs(end, 2:end - 1)];
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d3 = reshape([2 * n3 - 1; 2 * n3], 1, 2 * (nelx + nely - 2));
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% right+up boundaries
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n4 = [nodenrs(2:end - 1, end)', nodenrs(1, 2:end - 1)];
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d4 = reshape([2 * n4 - 1; 2 * n4], 1, 2 * (nelx + nely - 2));
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d2 = setdiff(alldofs, [d1, d4, d3]);
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for j = 1:3
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ufixed(3:4, j) = [e0(1, j), e0(3, j) / 2; e0(3, j) / 2, e0(2, j)] * [lx; 0]; % set lx=ly=1
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ufixed(7:8, j) = [e0(1, j), e0(3, j) / 2; e0(3, j) / 2, e0(2, j)] * [0; ly]; % down->up,-nely
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ufixed(5:6, j) = ufixed(7:8, j) + ufixed(3:4, j);
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end
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wfixed = [repmat(ufixed(3:4, :), nely - 1, 1); repmat(ufixed(7:8, :), nelx - 1, 1)];
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testNum = 3;
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end
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