Effect of damage modelling in numerical simulation of crash energy absorption behaviour of crush tubes and validation with experiments

Crush tubes are employed as frontal energy absorbing structures in road vehicles and they absorb crash energy by plastic deformation. Finite element analysis (FEA) is being used extensively in the early stages of crush tube design to study the method and magnitude of plastic deformation precisely ahead of prototyping and testing. Accurate definition of crush tube's material including its post-yield and damage/failure behaviours forms a fundamental part of FEA for a realistic prediction of crush tube's response to crash impact loads. Often, for the sake of simplicity or unavailability of data, it is a common practice in numerical simulations to ignore the damage criterion which leads to substantial differences between FEA predictions and experiments. Therefore, this article demonstrates the importance and effect of damage modelling in numerical simulation (FEA) of crash energy absorption behaviour of crush tubes. The results of numerical simulation of crush tubes with and without consideration of proper damage model are compared with carefully conducted axial crush experiments. The results show that the inclusion of damage model in numerical simulations improve the closeness of predictions compared to experiments irrespective of the magnitude of plastic strains in crush tubes. Crush tubes made of aluminium alloy H30 in WP condition and stainless steel SS304 grades are considered for this study.