Effect of High Strain Rate and Temperature on the Mechanical Response of Graphene-Reinforced Aluminum Foam

Closed-cell aluminum foam is a particular type of lightweight metallic material that can sustain considerable deformation under nearly constant stress, which is known as plateau stress. Thus, under dynamic loading, aluminum foams can be used for energy absorption. However, these foams have a low plateau stress and are generally unsuitable for carrying structural loads. To improve foam mechanical properties, graphene reinforcement has been used to enhance its dynamic mechanical response for applications at room temperature and high temperatures. For this investigation, aluminum foams reinforced with graphene concentration varying between 0.2 and 0.62 wt.%, manufactured using the liquid metallurgy route, were studied. The compressive dynamic behavior of this foam has been studied over a range of high strain rates up to 2200 s^-1 using the split-Hopkinson pressure bar (SHPB) apparatus. The mechanical response was studied at high temperatures of 473 K, 623 K, and compared to room temperature of 298 K. Among the four different graphene concentrations (0.20 wt.%, 0.40 wt.%, 0.50 wt.% and 0.62 wt.%) studied, 0.62 wt.% displayed the maximum value of peak stress, plateau stress, and energy absorption. The experimental data obtained in the present study are supported using an empirical model. It is observed that at high temperature, the values of peak and plateau stress decreased when compared with the values obtained at room temperature for reinforced foam. However, the high-strain-rate response of the reinforced foam at high temperature was equal to or better than the response of unreinforced foam under similar loading conditions at room temperature.