Developing elasto-plastic models without establishing any expression for the yield function

This paper presents a procedure for developing elasto-plastic material models from a dissipation function and kinematic constraint that obviates the need to establish an expression for the yield function. This method could be applied to a wide range of different materials, but it is particularly suitable for testing new models of granular materials. This is because there is often a difficulty associated with finding an algebraic expression for the yield function for appropriate dissipation functions combined with realistic dilatancy rules. The procedure presented in this paper allows the approach to fulfill its potential for the easy incorporation of physical insight into the dissipation function and kinematic constraint without being hindered by algebraic complexity. The method is applied to the familiar von Mises model and also to a model for granular materials that incorporates a realistic dilatancy rule and extends into three dimensions a model presented in earlier work. Copyright © 2010 John Wiley & Sons, Ltd.