Identification of material parameters in constitutive models for metal and metal/polymer composite sheets by elasto-plastic inverse analyzes

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The aim of the present research is to propose a new approach for the identification of the mechanical properties of individual component layers of metal or metal/polymer composite sheets by elasto-plastic inverse analyses. The present findings are summarizing as follows :(1) For a bimetallic sheet, a set of material parameters in a constitutive model of cyclic plasticity for individual layer was successfully identified by minimizing the difference between the experimental data (the tensile load vs strain curve in uniaxial tension and the bending moment vs curvature diagram in cyclic bending) and the corresponding results of numerical simulation. The method was verified by comparing the simulated results using the constitutive model incorporating the identified material parameters (eight parameters for each layer, i.e., totally sixteen parameters in an isotropic/kinematic haredening model) with the experimental results on a stainless steel/aluminirn composite sheet.(2) This method was also applied to determine the material parameters for a polymer in a polymer-layer sandwiched aluminium sheeL For that purpose, the experimental data of the transverse shear deformation of the polymer-layer appearing in V-bending experiments was used.Furtheremore, it is worth noting that :- this method has an advantage of using the experimental data for a whole composite sheet but not for individual component layers (the identificationis is possible without performing a time-consuming process of the removal of a layer from the composite sheet).- the identification procedure is based not on the conventional try-and-error approach but on an advanced optimization technique.