Seite - 237 - in Stoßprobleme in Physik, Technik und Medizin - Grundlagen und Anwendungen

9.4 QuellcodefürviskoelastischenschiefenStoßmitGleiten 237 23 kz = 4*dx; % Steifigkeit z 24 kx = 8/3*dx; % Steifigkeit x 25 cont = zeros(1,N); % = 1: Element in Kontakt 26 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 27 %%%%%%%%%%%%%% Zeititeration (explizites Euler-Verfahren) %%%%%%%% 28 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 29 while true; 30 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 31 %%%%%%%%%%%%%%%%%%%%% Normalkontakt %%%%%%%%%%%%%%%%%%%%%%%%%% 32 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 33 uzm = uzm + vz*dt; % neue Verschiebung z 34 uz = uzm - g; % neue Feder-Verschiebung 35 if vz > 0 % Kompressionsphase 36 cont = (uz > 0); % Kontakt Kompression 37 uz = uz.*cont; % neg. Werte loeschen 38 fz = (G*uz + eta*vz*cont)*kz; % neue Elementkraefte 39 else % Restitutionsphase 40 fz = (G*uz.*cont + eta*vz*cont)*kz; 41 cont = (fz > 0); % Kontakt Restitution 42 fz = fz.*cont; % neg. Werte loeschen 43 end 44 if sum(cont) == 0 45 break; % Stoss beendet 46 end 47 Fz = 2*sum(fz); % gesamte Normalkraft 48 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 49 %%%%%%%%%%%%%%%%%%%% Tangentialkontakt %%%%%%%%%%%%%%%%%%%%%%% 50 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 51 ux = ux.*cont + vxk*dt*cont; % ux bei no-slip 52 fx = (G*ux + eta*vxk*cont)*kx; % Kraefte bei no-slip 53 sl = (abs(fx) > mu*fz); % = 1: Element gleitet 54 st = (1 - sl).*cont; % = 1: Element haftet 55 uxs = (eta*uxa.*sl + mu*dt/kx*fz.*sl.*sign(fx))/(G*dt + eta); 56 % Verschiebung der gleitenden Elemente (aus Kraft bekannt) 57 vxs = (uxs - uxa.*sl)/dt; % Geschw. mit Gleiten 58 fx = fx.*st + (G*uxs + eta*vxs)*kx; % Kraefte mit Gleiten 59 ux = ux.*st + uxs; % korrigierte ux 60 uxa = ux; % Aktualisierung uxa 61 Fx = 2*sum(fx); % gesamte Reibkraft 62 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 63 %%%%%%%%%%%%%%%%%%% makroskopische Dynamik %%%%%%%%%%%%%%%%%%% 64 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 65 vz = vz - Fz*dt/M; % neue Geschwindigkeit z 66 vxk = vxk - Fx*dt/M/K; % neue Geschwindigkeit x 67 end 68 COR = [-vz/vz0 -vxk/vxk0]; % Stosszahlen