Energy-absorbing Behavior of aluminum foams:: Head impact tests on the A-pillar of a car

Hundreds of compression tests have been performed in recent years to investigate the energy-absorbing behavior of metal foams, which is mainly characterized by the "deformation plateau". Plateau value and plateau length describe the basic behavior quite well and allow comparison of various foams, but in practice the geometry of the absorbing component and the assembly in the system with supports and panels also influence the behavior. The aim of this work was to evaluate the energy-absorbing behavior Of an aluminum foam absorbing element in an A-pillar system of a real car. In cooperation with the Austrian car manufacturer Steyr-Daimler-Puch Fahrzeugtechnik, a Magna Steyr company, the deformation element in an A-pillar of a passenger car was developed and tested. The geometry was given by the design of the steel frame and the cover panel of the pillar. The deformation elements were foamed at ARC Leichtmetallkompetenzzentrum Ranshofen GmbH (LKR) by the powder metallurgical process route. The head impact against the A-pillar in overturning was simulated by the standard test procedure FMVSS 201u and the head injury criterion (HIC) was measured. The head impact tests were performed by impact of a free motion head (FMH) dummy against the A-pillar in a complete car mounted in a special test rig. In a couple of test runs, the required HIC of less than 1000 could be achieved. The measured HIC values depend on the density and the structure of the aluminum foam, as well as on the deformation element geometry. These parameters were investigated and simulations concerning component behavior were carried out.