Mississippi State University
Lacy, Thomas E. Jr.
Date of Degree
Graduate Thesis - Open Access
Master of Science
James Worth Bagley College of Engineering
Department of Aerospace Engineering
Energy dissipation during penetration is an important consideration in materials selection for lightweight armoring to protect against hypervelocity impacts (HVIs). Impact-induced glass transition in polymeric materials has been observed to increase energy dissipation during penetration. Incorporating unconventional armor materials like polymers could improve performance in these types of applications. A series of HVIs was performed, with impact velocities over the range of 2-7 km/s, on samples of ultra-high molecular weight polyethylene and poly(methyl methacrylate). A relationship between back face debris cloud velocity and impact velocity was developed for each material. Damage zone sizes were compared, offering insights into the effects of molecular architecture on stress delocalization and energy dissipation during hypervelocity perforation. Thermal analysis of the two material systems provides quasi-static glass transition temperatures, as well as melting and crystallization temperatures. The apparent failure mechanisms, in conjunction with thermal analysis, were used to explain the relative performance of each material.
Bowering, Michael Hunter, "Strain rate effects on energy dissipation during hypervelocity penetration of polymeric materials" (2018). Theses and Dissertations. 4064.