Static and dynamic behavior of combined composite aluminium tube for automotive applications

The objective of this work is to study the crushing behavior and the influence of surface treatments on an aluminium alloy before bonding with a carbon/epoxy composite. Two geometries of aluminium circular tubes are used, allowing a stable crushing mode. Chemical etching and degreasing were applied to the aluminium tube to improve adhesion between composite and aluminium. To compare the effects of these surface treatments, the as-received aluminium alloy is used. Under dynamic compression conditions, results have shown that the influence of surface treatments of multi-material structures was not significant in terms of specific energy absorption. Under quasi-static compression conditions, results have shown a 30% increase in specific energy absorption, if we compare the chemically etched tube with the as-received one. For the thinner aluminium tube, if we compare the aluminium tube without reinforcement and the aluminium tube with reinforcement, the same crushing mode has been observed whatever the surface treatment. By contrast, for the thicker aluminium, a crushing mode change was observed. Since the crushing mode changed, the reinforcement applied to the aluminium tube has decreased the capacities of structures tested to absorb energy. On the other hand, reinforcement applied to the thinner aluminium tube increased the specific energy absorption of the tube. To differentiate the ability of a tube to dissipate energy (i.e. characterized by the specific energy) and the ability of a tube to deform itself (i.e. characterized by the crush distance), a new coefficient, termed Abb, was defined to qualify an energy absorber as the ratio of the kinetic energy of the measuring bar after the crushing to the initial kinetic energy.