Experimental investigation of energy dissipation of aluminum matrix syntactic foam under impulsive loading

Metal matrix syntactic foams, comprising hollow microspheres embedded within a metallic matrix, represent an innovative class of porous materials that integrate both structural and functional properties. These materials are renowned for their lightweight, high specific strength and exceptional energy absorption capacity, making them highly promising for applications in automotive crash protection, vibration damping, aerospace, military equipment, and marine engineering. In this study, aluminum alloy-based syntactic foams were fabricated using hollow ceramic microspheres of three different size ranges (75–125 µm, 125–250 µm, and 250–500 µm), with an approximate volumetric fraction of 60 %. The material response and energy dissipation performance of these syntactic foams under shockwave loading were evaluated using a shock tube apparatus driven by commercially available nail gun cartridges. Under impulsive loading, the syntactic foams exhibited global transient displacement due to elastic deformation, followed by rapid recovery to their original configuration. The inherent damping characteristics of the foams induced free oscillation, with oscillation amplitudes progressively attenuating over time. Experimental data demonstrated that both the size of the ceramic microspheres and the intensity of the impulse load significantly influenced the energy dissipation behavior of the syntactic foams. The primary energy dissipation mechanism was attributed to the initiation and propagation of microcracks within the ceramic microspheres. The number of potential sites for the initiation of these microcracks were found to have a positive influence on the energy dissipation efficiency.