Mehdi Shekarbeigi - Ph.D Student of Civil Engineering , Institute of Geotechnical Engineering .University of Boku, Vienna ,Austria
Wei Wu - Institute of Geotechnical Engineering .University of Boku, Vienna ,Austria

The so-called hypoplastic constitutive equations, defined by the equation T = h(T, D), are limited by the requirement that h is linear in D. Dropping thisrequirement and retaining positive homogeneity of the first degree in D leads to a broader class of equations which can be called hypoplastic. Such equationsare appropriate to describe the anelastic behaviour of granular materials. Some properties of hypoplastic equations are discussed in this paper including thenew notions of yield and bound surfaces which are given a completely different meaning than in classical elastoplasticity. Possibilities to enlarge hypoplasticity towards rate-dependence and more complex intrinsic memory of the material are pointed to.

Hypoplastic , plastic, elasticity, Constitutive Model