A numerical-experimental coupled method for the identification of model parameters from µ-SPIF test using a finite element updating method

Abstract

Single Point Incremental forming (SPIF) is a technology that allows obtaining complex parts using a hemispherical end tool by applying a local deformation process in sheet metal. This dieless process presents the advantage of high formability limits and low cost. The increasing need for micro components, namely in the medical industry (implants and medical tools and accessories), has contributed to the development of the micro single-point incremental forming (µ-SPIF) technique. However, this technique requires meeting certain challenges related to tool wear, resistance and precision of the manufactured parts, and increased formability. So, understanding the deformation and failure mechanisms in µ-SPIF is important to achieve improved formability. This paper aims to improve the predictions of the shear-modified GTN damage model by proposing an identification procedure for its numerous material parameters based on an inverse method coupling the numerical predictions with experimental results. The extended GTN model is first implemented into the finite element code Abaqus. The numerical approach is assessed through numerical simulations under shear and uniaxial tension loading. Then, a complete methodology is proposed to identify the set of material parameters using tensile and micro single-point incremental forming (µ-SPIF) experimental results. The identification approach is based on the comparison of the numerical and experimental forces used to carry out the micro-incremental forming test with a pyramidal shape tool. To show the pertinence of the identification procedure, the numerical predictions of the modified GTN model with these material parameters are compared to the experimental results of µ-SPIF tests with different tool paths and geometrical forms. Finally, It is shown that the shear modification of the GTN model can predict the failure of sheets during metal forming.