Abstract: The physical meaning of Poisson’s ratio is discussed. The relationships among the Poisson’s ratio and the longitudinal and transverse stresses under uniaxial strain shock loadings, and the relationship between the Poisson’s ratio and the sound velocity in quasi-elastic deformation region are presented. Poisson’s ratios of LY12 aluminum alloy materials are calculated based on the sound velocities measured at shock pressures from 20 GPa to 131 GPa. It is found that, while the Poisson’s ratios keep almost constant, i.e., 0.32, before shock-melting happens, it increases rapidly in the shock-melting solid-liquid mixed phase region and approachs the theoretical limit of Poisson’s ratio, i.e., 0.5, as shock-melting completes, which may provide us a useful way for identifying the shock induced melting zone.

Key words: solid mechanics, Poisson’s ratio, sound velocity, uniaxial strain, quasi-elasticity, shock-induced melting