I have found in the Annual Report 2006 of Discrete Element Group for Hazard Mitigation, page E5 (http://geo.hmg.inpg.fr/frederic/Discrete_Element_Group_FVD.html) expressions for kn, ks:
if E = D/S * Kn * ( beta + gamma * Ks/Kn ) / (alpha + Ks/Kn) v = (1 - Ks/Kn) / (alpha + Ks/Kn) hence Kn = E * S/D * (1 + alpha) / [ beta * (1 + v) + gama * (1 - alpha*v) ] Ks = Kn * (1 - alpha*v) / (1 + v) where alpha, beta, gamma is the parameters will be identified; E, v is Young's Modulus and Poisson ratio. However, I on former do not understand as they have turned out and how can be used in the linear contact model Fn = kn * xn, Ft = kt * xt where xn - depth penetration, xt - relative tangential displacement. I'm interested to that I write the PhD thesis about modelling the granulated materials in which there is a review of various models of interaction: linear and nonlinear viscoelastic models (Cundall*Strack, Kuwabara&Kono), Hertz theory, elastoplastic models (Walton&Braun, Thronton), linear and nonlinear tangential interaction (Mindlin&Derisevich, Walton&Braun). In the linear models factors of elasticity and dissipation are deduced from the decision of the differential equation of pair interaction and __empirically__ defined parameters, such as coefficient of restitution and duration of pair impact. In the nonlinear models constructed on the basis of the theory of elasticity Hertz, the given parameters define on the basis of __clearly interpreted physical parameters__ of a body: the Young's Modulus and Poisson's ratio. Therefore it was very interesting to me to learn how it is possible to use Young and Poisson in the simple and attractive to calculations linear models of interaction. _______________________________________________ Yade-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/yade-users
