On capturing rate-dependent anisotropic behavior of sheet metal forming using a viscoplastic computational framework

Abstract

Manufacturing of metal sheets—of critical importance in the automotive, aerospace, and railway industries; is notoriously prone to uncertainty and inaccuracy driven by the lack of control in responding to anisotropic behavior developed during a rate-dependent forming process. Various expensive efforts have been made to evaluate these complex behaviors largely based on trial-and-error approaches, implying a high-fidelity predictive numerical tool is inevitable to promote a cost-effective solution. In this work, a high fidelity anisotropic-viscoplastic constitutive model framework based on Hill 48 yield function, isotropic hardening, and Cowper-Symonds viscoplasticity is developed to investigate the rate-dependent anisotropic behavior of sheet metals. This model is holistically implemented as a user-defined material subroutine (VUMAT) in ABAQUS software. The quality of numerical results is evaluated through comparison with experimental works. In the quasi-static and dynamic tensile test, the stress-strain curves obtained from numerical simulation using the developed constitutive model are in excellent agreement with experimental results. Furthermore, numerical simulation of cup drawing test using the developed constitutive model can accurately predict the earing height compared to experimental results. In addition, some novel relationships in terms of plastic rate-dependent anisotropic behavior of sheet metal forming are successfully established through the extended use of the validated numerical model.