V >>> Bruno, how does this value compare to critical timestep calculated from >>> elastic wave propagation speed along the particle calculated for >>> cotinuum, i.e. , which is 2*particle diameter / sqrt(Young's modulus / >>> density)? >>> I see how it compares now, with global stiffness approach we have :
- The stiffness of one contact is proportional to D*E (D : particle diameter, E elastic modulus) - The mass of one particle is proportional to density*pow(D,3) So, if a particle has only one contact, its critical timestep (with global stiffness approach) will be : sqrt(mass/stiffness) = D*sqrt(density/E) = your equation. Advantage : The underlying physics is the same but your equation is faster. Potential problems : -As soon as a particle has two contacts it will explode. -If shear stiffness is high compared to normal stiffness (unusual situation in fact), it will explode. Conclusion : you need to find a reasonable value for a security coefficient to include in your expression. Bruno >>> O -- _______________ Chareyre Bruno Maitre de conference Institut National Polytechnique de Grenoble Laboratoire 3S (Soils Solids Structures) - bureau E145 BP 53 - 38041, Grenoble cedex 9 - France Tél : 33 4 56 52 86 21 Fax : 33 4 76 82 70 43 ________________ _______________________________________________ Yade-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/yade-users
