Effect of Laser Forming on the Fatigue Behavior of Metal Foams

Metal foam is an excellent lightweight material with promising industrial applications. Laser forming has been studied and shown to be a viable non-contact method to shape metal foam panels into desired geometry without fracturing the foam’s cellular structure. However, whether laser forming alters the fatigue performance of metal foam has not been well understood. This study focuses on the tension-to-tension fatigue behavior of closed-cell metal foam before and after laser forming. Fatigue tests were conducted at different load levels on as-received and laser treated aluminum alloy foam with two different scanning patterns. Fatigue life were comparably tested and subsequently investigated, and fracture surface was closely examined to relate to the fluctuation in fatigue life and varying data scatter of fatigue life between as-received and laser formed specimen. Numerical models with equivalent foam geometry were used to investigate the strain distribution after laser forming, and helped to elucidate the fatigue life improvement after laser forming. Fatigue simulations where foam structure approximated with regular Kelvin cell was conducted demonstrate the effect of stress concentration on fatigue life. Generally, laser forming resulted in an improvement in fatigue performance of the aluminum alloy foam.