The Gruneisen Constant of Porous Materials in Energy Deposition Materials
PICATINNY ARSENAL DOVER NJ
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It is proposed that the usual energy deposition, e.g., electron beam, experiments, as well as the usual shock introduction, e.g., flyer plate, experiments do not yield a true Gruneisen parameter of porous materials. It is proposed that in a porous material stress relief occurs within the time that energy is being deposited, or before the final state is reached in a flyer plate experiment. Both types of experiments are analyzed and correlated and agree with the ideas put forward here. Energy deposition experiments of Shea, Mazella, and Avrami porous PETN, and flyer plate experiments of Boade sintered porous copper, are considered. Wave propagation in porous materials is considered in some detail, and it is concluded that in such materials macroscopic measurements can not always be used to determine microscopic parameters. It is proposed that a porous material acts as a diffraction grating with respect to a shock wave, and that unidirectional one-dimensional strain does not hold.
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