Abstract

A unique dual pendulum system was developed to measure single-impact compression responses of foamed polymers. The data, complemented with a mathematical model of impact, led to measures of the material’s energy absorption, compression modulus, and damping. Results are presented for a class of open-celled foamed polymers specifically developed for shock mitigation. The experiments employed such materials of four different densities, with impact times ranging in the 1 to 5 ms range and mean impact stresses up to 160 kN/m². The results for these materials showed: (1) energy losses of up to 50% of incident energy, with a peak energy absorption per unit volume of 18 kJ/m³; (2) peak compression modulus of 880 kN/m² with strain rates approaching 200 s⁻¹; (3) a mean damping factor of 0.258 with a standard deviation of 0.029. Such data are of practical importance in many shock-mitigating applications, including prostheses, floor pads and cushions, gloves for hand-held vibrating tools, grips for hockey sticks and tennis rackets, and soles for sports shoes.

Keywords

foamed polymers, impact response

Authors