Study On The Quasi-elastic Release Behavior And Spallation Of LY12 Aluminum Alloy Under Strong Shock Loading

Knowledge of the strength and release behavior of materials under strong shock loadings is of particular importance to an overall understanding of the dynamic behavior and to a thorough recognizing of the spallation phenomena. In this doctoral thesis, shear strength and quasi-elastic release behavior of an LY12 aluminum alloy were systematically and intensively studied based on the release wave velocity measurements by using VISAR (velocity interference system for any reflector) techniques, from which the constitutive relation that involves the release processes effects was discussed; Some main aspects of the spallation behavior of LY12 aluminum alloy were studied experimentally, theoretically and numerically, by using the triangle shock loadings resulting from the attenuations and interactions of a rectangle shock wave with the catch-up release waves; A spallation model based on the voids conglomerating was discussed. The outlines and main achievements are as follows:1. Principles and the key techniques of the high-pressure release wave velocity measurements for shock-compressed materials by VISAR techniques were described systematically.Symmetrical impact and reverse-impact experiments were designed and conducted with the two-stage light-gas gun at LSD, with impact velocities of the flyer plates ranging from 2.1km/s to 5.8km/s, corresponding peak stresses in the aluminum samples from 20～131GPa. High quality VISAR records with high signal-to-noise ratio were obtained. Computational methods of data processing were developed to determine the particle velocity profile at the "LY12 Al/LiF "interface from the VISAR records as well as the release wave velocity profile of the sample itself.Release paths involving the material strength effects were calculated from measured release wave or sound velocities. It reveals that the release path of shocked LY12 Al exhibits a significant departure from that of the ideal elastic-plastic response, and this departure decreases with the increasing of the shock pressure.2. The release wave velocities of LY12 Al from 20.3～131GPa were determined, which revealed the unique behavior of the longitudinal velocity in the solid-liquid...