The objective of this project is to understand the basic physics of rapid penetration into granular materials in general, and sand in particular. The primary approach is to visualize the in situ response of granular media by using a combination of high-speed photography and DIC (digital image correlation). A key aspect of this approach is use of transparent soil surrogates that mimic the behavior of natural sand when penetrated.
Many new experimental techniques were developed in the course of this effort. Measurements of the resisting stress for soil penetration have been obtained with unprecedented precision and over an unprecedented wide range of impact variables. New transparent surrogates that better mimic the high strain rate behavior of sand have been developed. New DIC analysis techniques have been developed. New ways to visualized in situ movements in sand during penetration have been devised, and have been demonstrated for static and dynamic penetration.
The data provides unprecedented understanding of the fundamental mechanisms governing the response of a granular medium to penetrators. Influence of important parameters including penetrator properties and target density on the characteristics of the flow field and soil-projectile interactions were studied. The improved understanding of the fundamental physics of projectile penetration will be used to develop new analytical models for predicting penetration.
This project has supported four PhD students and two masters students. There have been over 18 journal publications , plus one book. Additionally, there have also been several presentations at conferences and U.S. Army and U.S. Air Force Research Laboratories.
