EFFECT OF LASER FORMING ON THE ENERGY ABSORBING BEHAVIOR OF METAL FOAMS

摘要

Metal foam is light in weight and exhibits an excellent impact absorbing capability. Laser forming has emerged as a promising process in shaping metal foam plates into desired geometry. While the feasibility and shaping mechanism has been studied, the effect of the laser forming process on the mechanical properties and the energy absorbing behavior in particular of the formed foam parts has not been well understood. This study comparatively investigated such effect on as-received and laser formed closed-cell aluminum alloy foam. In quasi-static compression tests, attention was paid to the changes in the elastic region. Imperfections near the laser irradiated surface were closely examined and used to help elucidate the similarities and differences in as-received and laser formed specimens. Similarly, from the impact tests, the dynamically induced deformation and crush band formation were investigated with a modified Charpy impact test scheme. Differences in specific energy absorption were studied and were related to the defects formed during laser forming process. The relative density distribution and evolution of foam specimens were numerically investigated. Laser induced imperfections lead to very minor decrease in the energy absorbing ability of the metal foam, and laser forming still remain as a viable shaping process for metal foams.