Determination of effective shear modulus of shock-compressed LY12 Al from particle velocity profile measurements

Unloading wave profile measurements using the velocity interference system for any reflector technique were performed on LY12 Al over shock stress ranging from ∼20to∼100GPa, from which longitudinal and bulk sound velocities along the quasielastic release path were evaluated. Based on the intrinsic relations under uniaxial strain conditions, the effective shear modulus defined by Cochran and Guinan (Lawrence Livermore National Laboratory Report No. UCID-17105, 1976) was correlated to the longitudinal and bulk sound velocities. Results show that the effective shear modulus calculated from the measured sound velocities decreases rapidly with the release stress and can be expressed approximately as a linear function of the release stress; the slope of the linear function depends the initial shock-loading stress. By using this linear function of the effective shear modulus, the performed numerical simulations well reproduce the release wave traces of the Al alloys observed in the present work and reported in l...