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Mechanical properties of silicone based composites as a temperature insensitive ballistic backing material for quantifying back face deformation

Edwards, Tara D., Bain, Erich D., Cole, Shawn T., Freeney, Reygan M., Halls, Virginia A., Ivancik, Juliana, Lenhart, Joseph L., Napadensky, Eugene, Yu, Jian H., Zheng, James Q., Mrozek, Randy A.
Forensic science international 2018 v.285 pp. 1-12
ambient temperature, certification, clay, deformation, face, forensic sciences, infrastructure, mechanical properties, safety equipment, silicone, thermodynamics
This paper describes a new witness material for quantifying the back face deformation (BFD) resulting from high rate impact of ballistic protective equipment. Accurate BFD quantification is critical for the assessment and certification of personal protective equipment, such as body armor and helmets, and ballistic evaluation. A common witness material is ballistic clay, specifically, Roma Plastilina No. 1 (RP1). RP1 must be heated to nearly 38°C to pass calibration, and used within a limited time frame to remain in calibration. RP1 also exhibits lot-to-lot variability and is sensitive to time, temperature, and handling procedures, which limits the BFD accuracy and reproducibility. A new silicone composite backing material (SCBM) was developed and tested side-by-side with heated RP1 using quasi-static indentation and compression, low velocity impact, spherical projectile penetration, and both soft and hard armor ballistic BFD measurements to compare their response over a broad range of strain rates and temperatures. The results demonstrate that SCBM mimics the heated RP1 response at room temperature and exhibits minimal temperature sensitivity. With additional optimization of the composition and processing, SCBM could be a drop-in replacement for RP1 that is used at room temperature during BFD quantification with minimal changes to the current RP1 handling protocols and infrastructure. It is anticipated that removing the heating requirement, and temperature-dependence, associated with RP1 will reduce test variability, simplify testing logistics, and enhance test range productivity.