THE IDENTIFICATION OF PARAMETERS FOR VISCOPLASTIC MODELS VIA FINITE-ELEMENT METHODS AND GRADIENT METHODS

In this work we present a unified strategy for identification of mater ial parameters of visco-plastic models from test data of complex struc tures. For consideration of the associated inhomogeneous deformations and stresses the finite-element method is used. The objective function of least-squares type is minimized by a method based on gradient eval uations, such as an SQP method or a projection algorithm due to Bertse kas. The sensitivity analysis, i.e. the determination of the gradient of the objective function, is explained in detail. As a result a recur sion formula is obtained. In the numerical examples we compare gradien t-based methods with evolutionary methods for homogeneous problems. Co ncerning inhomogeneous problems we discuss the results obtained for a material law due to Steck.