Characterization and modeling of the deformation and damage behavior of aluminum materials for crash simulation

Relevant characterization and reliable modeling of deformation and damage behavior are necessary for the assessment of crash safety of automobile components of aluminum alloys. Since the fracture strains of aluminum materials are relatively low, crash simulations without taking into account damage behavior can dramatically overestimate the load-carrying capacity and the absorbed energy of a structural component. Although different damage models e.g. Johnson-Cook [1], DcRc [2] and Gurson [3] are available in crash codes, most crash simulations do not take into account the damage behavior. The reason for the lack of damage modeling is that there are no standard procedures concerning the characterization of material behavior, the selection of an applicable damage model and the determination o f the corresponding damage parameters. In this work an evaluation chain including material characterization, numerical simulation with a suitable damage model, determination of damage parameters and verification by component tests has been established. The influences of the stress triaxiality on the deformation and damage behavior were taken into account in the experimental and numerical investigations. To describe both ductile fracture caused by void growth and shear fracture, the micromechanical Gurson model was used in combination with the phenomenological Johnson-Cook damage model for the simulations. The applicability of the damage model for crash simulation was demonstrated by simulation of component tests in a crash relevant load case.