Ductile damage prediction in sheet and bulk metal forming

Abstract

This paper is dedicated to the presentation of an advanced 3D numerical methodology for virtual sheet and/or bulk metal forming simulation to predict the anisotropic ductile defects occurrence. First, the detailed formulation of thermodynamically-consistent fully coupled and fully anisotropic constitutive equations is given. The proposed constitutive equations account for the main material nonlinearities as the anisotropic plastic flow, the mixed isotropic and kinematic hardening and the anisotropic ductile damage under large inelastic strains. Second, the related numerical aspects required to solve the initial and boundary value problem (IBVP) are very briefly presented in the framework of the 3D finite element method. The global resolution schemes as well as the local integration schemes of the fully coupled constitutive equations are briefly discussed. Finally, some typical examples of sheet and bulk metal forming processes are numerically simulated using the proposed numerical methodology.

Prediction of necking in thin sheet metals using an elastic–plastic model coupled with ductile damage and bifurcation criteria

“…This allows the definition of a single couple of state variables related to the plastic flow. This idea has been extended later by Saanouni and co-workers (Badreddine et al., 2010, 2016, 2017; Ghozzi et al., 2014; Rajhi et al., 2014; Saanouni, 2008, 2012; Saanouni and Chaboche, 2003; Saanouni and Hamed, 2013; Saanouni et al., 1994, 2011; Yue et al., 2015) to the total energy equivalence assumption, from which a couple of effective state variables associated with each dissipative phenomenon can be defined.…”

Simulation of Sheet Metal Forming Processes Using a Fully Rheological-Damage Constitutive Model Coupling and a Specific 3D Remeshing Method

“…In another aspect, the micro-cracks are closed in compressive state and the module of elasticity could be able to restore to their initial values before the damage accumulates. This recovery effect of physical properties after closure of micro-cracks is called the quasi-unilateral effect [30][31][32][33][34][35][36][37]. It demands that the definition of effective state variable ( σ, ε) should be in the unilateral condition.…”

“…In this paper, the thermal effects are ignored [30][31][32][33][34][35][36][37][38][39][40] and the visco-plastic hardening yield stress is written as:…”

Modelling and Simulation of Sheet Metal Forming Processes

“…Nowadays, the automotive industry continues to drive the development of numerical simulation of sheet metal forming processes due to the strong environmental and safety standards that have led to the development of materials with better strength-to-weight ratio or new forming processes. Newly introduced materials allow to produce components from thinner sections, while maintaining satisfactory strength and stiffness, which ultimately results in a reduction of the overall structure mass, a crucial step to meet the ever-stringent standards of passenger safety and gas emissions [1]. However, as is well known, the increased mechanical strength of metallic materials is usually accompanied by a reduction of their ductility.…”