Dear All, I am losing myself a little to understand the contact model and contact stiffness used in YADE.Is it Linear Contact Model at present? I am trying to explain my question more details as follows,first explanation then my question. Reference: 01) Belheine.N et.al "Numerical simulation of drained triaxial test using 3D discrete element modeling"Computers and Geotechnics,2008 Kn=(kn(A)*kn(B))/(kn(A)+kn(B)))/r page number 03 (Article in press) 02) Kozicki.J et.al."A new open-source software developed for numerical simulations using discrete modeling methods" kn=r*(Kn(A)*Kn(B))/(Kn(A)+Kn(B))) page number 04 03) PFC3D,Theory and Background,Page Number 2-2,Article 2.1.1 Kn=(kn(A)*kn(B))/(kn(A)+kn(B))) kn, normal secant stiffness=Kn,normal tangent stiffness >>My question: what is the significance of "r" average radius,what are the >>difference among reference 01,02,03. Now inside of YADE (12.rc1) 04) pkg>dem>engine>engineunit>SimpleElasticRelationships.cpp //Real Eab = 2*Ea*Eb/(Ea+Eb); //Real Vab = 2*Va*Vb/(Va+Vb);
Real Dinit = Da+Db; //Real Sinit = Mathr::PI * std::pow( std::min(Da,Db) , 2); Real Kn = 2*Ea*Da*Eb*Db/(Ea*Da+Eb*Db);//harmonic average of two stiffnesses Real Ks = 2*Ea*Da*Va*Eb*Db*Vb/(Ea*Da*Va+Eb*Db*Va);//harmonic average of two stiffnesses with ks=V*kn for each sphere 05)pkg>dem>engine>standaloneengine>GlobalStiffnessTimestepper.cpp // Real alpha = sdecContactModel->alpha; // Real beta = sdecContactModel->beta; // Real gamma = sdecContactModel->gamma; // // Real Kn = abs((Eab*Sinit/Dinit)*( (1+alpha)/(beta*(1+Vab) + gamma*(1-alpha*Dab) ) )); // Real Ks = abs(Kn*(1-alpha*Vab)/(1+Vab)); 06>pkg>dem>engine>engineunit>MacroMicroElasticRelationships.cpp >>In 04 and 05 the equation is different,can anybody explain a little the >>difference and significance of 04 and 05. Thanks in advance. Regards, Mohammad Nurul Islam __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
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