Some recent advances of shock wave physics research at the Laboratory for Shock Wave and Detonation Physics Research

Progress made in recent years on three topics that have been investigated at the Laboratory for Shock Wave and Detonation Physics Research are presented in this report. (1) A new equation of state (EOS) has been derived which can be used from a standard state to predict state variable change along an isobaric path. Good agreements between calculations for some representative metals using this new EOS and experiments have been found, covering a wide range from hundreds of MPa to hundreds of GPa and from ambient temperature to tens of thousands of GPa. (2) An empirical relation of Y/G = constant (Y is yield strength, G is shear modulus) at HT-HP has been reinvestigated and confirmed by shock wave experiment. 93W alloy was chosen as a model material. The advantage of this relation is that it is beneficial to formulate a kind of simplified constitutive equation for metallic solids under shock loading, and thus to faithfully describe the behaviours of shocked solids through hydrodynamic simulations. (3) An attempt at microstructure characterization for a failure wave in shocked glass has been carried out for the first time. Analyses on both the fractal dimension of the cracks' propagating path and the degree of damage in the failed region qualitatively revealed that ZF1 glass has a much less damaged structure than K9 glass at nearly the same loading stress. Based on the above analysis, we conjecture inhomogeneous immiscible phases, more in K9 than in ZF1, distributed in the glass body of the intrinsic factor, exhibiting as numerous locally strained spots due to the shock induced different compressibilities between the matrix and the immiscible phases. When the surface cracks, activated by the shearing action of one-dimensional strain loading, propagate and arrive at the strained spot boundaries, new cracks would be generated, accompanied by crack turning and branching, and thus cause glass body fracturing and fragmenting. In other words, the more numerous the strained spots are, the more severely damaged the structure of the shocked glass.