Particle speed profiles for 6061-T6 Al alloy at shock stress amplitude of 2.1 GPa, calculated with the model of Austin and McDowell [2], (a) with C = 5353 m/s, where setting #1 means α0 = 1.0, β0 = 0.1, setting #2 means α0 = 0.9, β0 = 0.1, setting #3 means α0 = 0.9, β0 = 0.2, setting #4 means α0 = 0.8, β0 = 0.1, setting #5 means α0 = 0.8, β0 = 0.2, setting #6 means α0 = 0.7, β0 = 0.1, setting #7 means α0 = 0.7, β0 = 0.2, and (b) with α0 = 1.0, β0 = 0.1, where speed #1 means C = 5353 m/s, speed #2 means C = 5383 m/s, speed #3 means C = 5407 m/s, speed #4 means C = 5437 m/s, speed #5 means C = 5457 m/s, speed #6 means C = 5477 m/s, speed #7 means C = 5519 m/s, speed #8 means C = 5535 m/s. The experimental results [43] have been presented for comparison.