Mechanical properties and constitutive model of aluminum powder/rubber matrix composites compressed at various strain rates

Quasi-static and dynamic compression tests of aluminum powder/rubber matrix composites were conducted using a universal testing machine and Split Hopkinson Pressure Bar apparatus to evaluate their mechanical properties and establish a constitutive model. Stress-strain curves were obtained for composites containing 0 wt%, 10 wt%, 30 wt%, and 50 wt% Al for strain rates of 0.0083-5500 s(-1), and a modified Mooney-Rivlin-based model was proposed to describe the one-dimensional compression behavior of the composites. The 50 wt% Al specimen exhibited different hardening modes than the 0 wt% Al, 10 wt% Al, and 30 wt% Al specimens under quasi-static loading; the middle hardening stage was significantly weakened by the internal stacked arrangement of the aluminum powder, which caused the particles to break during compression. At high strain rate, distinct linear hardening was observed for the 30 wt% and 50 wt% specimens during the late deformation stage as the aluminum particles carried the main compressive load. Moreover, the composites exhibited clear strain-rate sensitivity, with their elastic modulus and engineering stress increasing linearly with increasing strain rate to substantially higher levels than those for the static tests.