Inverse modelling of constitutive parameters for elastoplastic problems

To obtain an improved identification of constitutive parameters to be used in finite element method simulations of elastoplastic deep-drawing processe s an inverse method was applied using an explicit finite element code to si mulate material tests. This problem was addressed by formulating the consti tutive parameter identification as an optimization problem. The method was to minimize the objective function defined as the error between the result from the material test and the result from the finite element simulation. T he optimization technique is based on the Levenberg-Marquardt method. The o bjective function was established in a least-squares sense where the design variables were the constitutive parameters of the material. The inverse me thod was started and when a global optimum was reached a set of constitutiv e parameters were identified. This was performed for both a linear hardenin g model and a power-law hardening model. It is shown that the inverse metho d predicts two models which qualitatively show the same overall characteris tics for the investigated material.