Numerical modeling of the deformation of AISI 304L using a tangent additive Mori-Tanaka homogenization scheme: Application to sheet metal forming

The aim of this paper is to demonstrate the capability of the tangent additive Mori-Tanaka scheme to simulate complex processes like sheet metal forming. The strengths of such homogenization scheme are exemplified by performing numerical simulations on AISI 304L grade classified as TRIP (TRansformation Induced Plasticity) stainless steel. Some experiments are also performed to validate numerical results. The experimental data are obtained from tensile tests performed at different strain rates. During tensile tests, the evolution of the martensite volume fraction and of the temperature in the AISI 304L specimen are registered. Material parameters of the phase transformation constitutive model (which is coupled with the elastic-viscoplastic Mori-Tanaka homogenization approach) are identified using tensile experimental data. To validate the Mori-Tanaka homogenization scheme, a special focus is devoted to the comparison of the simulated responses to experimental data obtained via tensile tests. Overall stress-strain responses and volume fraction of martensite are accurately reproduced. In addition, local responses in each phase are provided. Numerical simulations of cup drawing process were also performed and a parametric study on material parameters, friction coefficient, holder force enabled to capture the evolution of the punch force and volume fraction of martensite in the blank. An isotropization strategy is also proposed which consists in using an isotropic instead of the anisotropic tangent stiffness modulus for the reference medium to evaluate the tangent polarization tensor present in the interaction law. Relevance of this isotropization is discussed.

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