| Hypervelocity impact is an area of extreme interest in the research community. The U.S. Air Force has a test facility at Holloman Air Force Base which specializes in hypervelocity impact testing. This Holloman High Speed Test Track (HHSTT) is currently working toward a test vehicle speed above Mach 10. As the sled's speed has been increased to Mach 8.5, a material interaction develops which causes "gouging" in the rails or the sled's "shoes" and this can result in catastrophic failure.; Previous efforts in investigating this event have resulted in a choice of the most suitable computer code, CTH, and a model of the shoe/rail interaction. However, the dynamic stress models of the specific materials were not developed and the model was not validated against experimentation.; In this work, a summary of past and present research efforts, as well as the theoretical foundation of this field of study, are presented. A characterization of gouging is developed from an examination of a gouged rail from the HHSTT. A thermodynamic history of gouging is determined from the experimental evidence and an extensive study is performed that determines the specific material models.; The developed material dynamic strength models are validated utilizing several experimental tests which are successfully simulated using CTH. Additionally, a penetration theory is developed which provides insight into the gouging problem using an analytic approach that does not require the use of computationally intensive codes.; Based on the detailed examination of the materials and the validation of the material models within CTH, an evaluation of the HHSTT gouging phenomenon is performed. These simulations of the gouging problem replicate the experimentally observed characteristics and lead to recommendations to mitigate the occurrence of hypervelocity gouging. |
