Effect of impactor velocity on low velocity impact behavior of Al/SiC monocoque interpenetrating composites

This study investigates the impact behavior and energy absorption characteristics of C4 composites under different initial energy conditions. The force-displacement responses were recorded using a conical impactor on an impact testing machine. Three configurations of C4 composites with varying pore sizes (10PPI, 20PPI, and 30PPI) were tested at three initial impact energies (208 J, 312 J, and 416 J). The force-displacement curves revealed that the 30PPI-C4 exhibited the highest force gradient and maximum force, followed by the 20PPI-C4 and 10PPI-C4. The maximum force increased with increasing impact energy for all configurations. Velocity attenuation during impact tests showed a correlation with deformation and collapse mechanisms of the C4 composite. Energy absorption analysis indicated that the 30PPI-C4 exhibited the highest energy absorption per unit mass, followed by the 20PPI-C4 and 10PPI-C4. Visual inspection revealed circular indentations and shear cracks on the top and bottom surfaces, with increasing damage area and depth of indentation at higher impact energies. The 30PPI-C4 demonstrated better resistance to indentation and failure, along with higher specific energy absorption. The refined grains in the 30PPI-C4 contributed to crack mitigation and energy absorption. The C4 composites with higher SiC volume percentages exhibited reduced damage area and higher stability during impact tests. The study concludes that the 30PPI-C4 composite with 18 vol% SiC foam shows superior impact resistance and energy absorption properties, making it a promising material for impact-related applications.