Nonholonomic elastoplastic analysis involving unilateral frictionless contact as a mixed complementarity problem

This paper deals with the elastoplastic analysis of suitably discretized el astoplastic structures under frictionless unilateral contact conditions. Wh ilst the mathematical programming formulation we adopt can cater equally fo r hardening as well as softening path-dependent (nonholonomic) plasticity, the state problem involving softening is by far the more difficult to solve in view of the inherent nonconvex nature of the underlying mathematical pr ogram. We propose a novel description of a fairly general class of piecewis e linear softening laws and investigate use of an approximate stepwise holo nomic (path-independent) approach for capturing the evolution of the struct ure with softening and/or hardening constitutive laws. This finite-step pro blem is formulated in a specific way to lake advantage of the use of a robu st and industry-standard complementarity solver named PATH from within the GAMS modeling environment. We illustrate its application on truss-like stru ctures. (C) 2001 Elsevier Science B.V. All rights reserved.