Uskov V., Chernyshov M.

The problem of the interaction of blast shock wave with the elements of the uniform (cloth ballistic vests, sapper’s clothes, etc.) is the matter of topical interest at modern world due to the blast attacks of the terrorists. Some experiments with the animals (sheep, pigs, rabbits) as well as the studies in shock tubes frequently show us that multi-layer clothes and two-phase media of ballistic vests do not effectively quell, but even increase the overpressure of blast shock wave. Simple theoretical model of blast shock wave interaction with multi-layer protection surfaces based on linear and non-linear acoustical approach is presented at the first part of this work. The problem of shock wave interaction with the interface of two different media (so-called refraction of shock wave) is also solved at the linear approach. It is shown analytically that multi-layer surface with numerous abrupt transitions from the larger acoustical impedance of the media to the smaller one can effectively decrease the overpressure of blast shock wave. But the thickness of such rather effective protection surfaces is exactly too imposing for its usage at the elements of the uniform. The second part of this study is dedicated to the non-linear theoretical analysis of shock wave refraction at the interface of two perfect gases with equal or different molecular weights and ratios of specific heats. Possible schemes of the interaction and types of reflected shock or rarefaction waves are defined analytically as well as the criteria of refraction without the occurrence of reflected strong discontinuity. Results of the exact non-linear analysis are being compared analytically with the results of linear one. This work was supported by Russian Foundation for Basic Research (project code 04-01-00713).