Parameter identification of quasibrittle materials as a mathematical program with equilibrium constraints

The identification of the cohesive fracture parameters of quasibrittle mate rials forms the focus of the present work. This important and challenging t ask is formulated as an inverse problem, requiring the solution of a specia l type of constrained optimization problem known as a Mathematical Program with Equilibrium Constraints (MPEC). a key feature of which is the presence of complementarity conditions involving the orthogonality of two nonnegati ve vectors. We propose a simple scheme. based on transforming the MPEC into a standard nonlinear programming problem through appropriate smoothing of the complementarity constraints. for solving the parameter identification p roblem. Some computational results. using actual experimentally obtained da ta, are presented to assess the effectiveness of the approach. (C) 2001 Els evier Science BN. All rip,hts reserved.