Development of high crush efficient, extrudable aluminium front rails for vehicle lightweighting

•Simulations and experiments of new high energy absorption aluminium extrusions.•Framework for topography optimization of multi-cellular aluminium extrusions.•Identification of key topography sections for process control of mass and efficiency.•Developments of AA6xxx profiles that are comparable to AA7xxx profiles in crash. Understanding the behaviour of automotive structural components is essential for vehicle weight reduction and passenger safety. In this study, a novel framework is developed to design an optimized front rail that maximizes crash energy absorption characteristics. The new design is coupled with material and process development to provide a component with superior energy absorption and strength characteristics that is commercially sustainable. Simulations of the extrusion crush behaviour are performed using the anisotropic Barlat et al. (2003) Yld2000 yield functions. The simulations are compared to the dynamic crush results for this extrusion. The size of the structure is optimized using the response surface methodology, using artificial neural networks metamodels and simulated annealing optimization techniques. The specific energy absorption (SEA) is used as a single optimization objective function for maximizing energy absorption and minimizing mass. An analytical relationship that relates the SEA function to the crush efficiency is derived to show that a single optimization function parameter may be sufficient for mass minimization. Analysis is performed to identify key extrusion operational parameters and the wall thickness is identified as the most important parameter to control during extrusion.