The Physical Understanding of the Use of Coatings to Mitigate Hypervelocity Gouging Considering Real Test Sled Dimensions

Abstract : A dimensional analysis with accompanying numerical investigation is conducted. A simplified model of the real test sled is created that allows test sled dimensions to be converted to a numerical model for analysis. The dimensional analysis is used as a means of directly applying the numerical results to real test sled conditions. Similarity principles are studied and tested by comparing the results from scaled numerical models. Strain rate and other time dependent parameters are not scaled, but the effect of these parameters may be quantified and studied further. The dimensional analysis also provides a comprehensive approach to the test sled system by providing parameters whose affect on the final solution may be studied and quantified. The scaling parameters may also be used to determine which quantities must be modified so that results apply. Time and length scales for studying the problem are also determined using the dimensional analysis process. The use of coatings in mitigating damage to materials under high energy impact is also studied. The research is directed toward a scientific approach in determining the potential advantage of specific coatings acting under shock loading conditions and understanding the physics behind these advantages. Friction and heat generation effects are considered for rails with and without a coating.