45 lines
1.3 KiB
Mathematica
45 lines
1.3 KiB
Mathematica
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function [FORCE, STIFF] = cntelm2d(OMEGAN, ELXY)
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%***********************************************************************
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% SEARCH CONTACT POINT AND RETURN STIFFNESS AND RESIDUAL FORCE
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% IF CONTACTED FOR NORMAL CONTACT
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%***********************************************************************
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%
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ZERO = 0.D0; ONE = 1.D0; EPS = 1.E-6; P05 = 0.05; FORCE=[]; STIFF=[];
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XT = ELXY(:,3)-ELXY(:,2); %<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
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XLEN = norm(XT);%x1 x2<EFBFBD>ľ<EFBFBD><EFBFBD><EFBFBD>
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if XLEN < EPS, return; end
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%
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% UNIT NORMAL AND TANGENTIAL VECTOR
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XT = XT/XLEN;
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XN = [-XT(2); XT(1)];
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%
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% NORMAL GAP FUNCTION Gn = (X_s - X_1).N
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GAPN = (ELXY(:,1)-ELXY(:,2))'*XN;%<EFBFBD><EFBFBD>ʽ3
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%
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% CHECK IMPENETRATION CONDITION
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if (GAPN >= ZERO) || (GAPN <= -XLEN), return; end
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%
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% NATURAL COORDINATE AT CONTACT POINT
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ALPHA = (ELXY(:,1) - ELXY(:,2))'*XT/XLEN;%<EFBFBD><EFBFBD>ʽ11
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%
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% OUT OF SEGMENT
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if (ALPHA > ONE+P05) || (ALPHA < -P05), return; end
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%
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% CONTACT OCCURS IN THIS SEGMENT
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XLAMBN = -OMEGAN*GAPN;
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%
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% DEFINE VECTORS
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NN = [XN; -(ONE-ALPHA)*XN; -ALPHA*XN];%2*3 <EFBFBD><EFBFBD>ʽ16
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% TT = [XT; -(ONE-ALPHA)*XT; -ALPHA*XT];
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% PP = [ZERO; ZERO; -XN; XN];
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% QQ = [ZERO; ZERO; -XT; XT];
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CN = NN;%ȥ<EFBFBD><EFBFBD>-֮<EFBFBD><EFBFBD><EFBFBD>IJ<EFBFBD><EFBFBD><EFBFBD>
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% CN = NN - GAPN*QQ/XLEN;
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% CT = TT + GAPN*PP/XLEN;
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%
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% CONTACT FORCE
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FORCE = XLAMBN*CN;
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% FORM STIFFNESS
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STIFF = OMEGAN*(CN*CN');
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end
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