Linking Theory to Practice: Predicting Ballistic Performance from Mechanical Properties of Aged Body Armor
Amanda L. Forster, Dennis D. Leber, Amy E. Engelbrecht-Wiggans, Virginie A. Landais, Allen Chang, Emilien J. Guigues, Guillaume Messin, Michael A. Riley
It has long been a goal of the body armor testing community to establish an individualized, scientific-based protocol for predicting end-of-life of fielded body armor ballistic performance. A major obstacle in achieving this goal is that the test methods used to ascertain ballistic performance are destructive in nature and require large sample sizes. Using both the Cunniff and Phoenix-Porwal models, we derive two separate but similar theoretical relationships between the degradation in mechanical properties of aged body armor and its decreased ballistic performance. We present two studies used to validate the derived functions. The first correlates the degradation in mechanical properties of fielded body armor to that produced by a laboratory accelerated aging protocol. The second examines the ballistic resistance and extracted-yarn mechanical properties of new and laboratory aged body armor, made from poly (p- phenylene-2,6-benzobisoxazole), or PBO and poly(p-phenylene terephthalamide), or PPTA. We present correlations found between the tensile strengths of yarns extracted from armor and the V50 ballistic limit when significant degradation of the mechanical properties of the extracted yarns was observed. These studies provided the basis for a validation dataset from which we compare the experimentally measured V50 ballistic limit results to the theoretically predicted V50 results. The theoretical estimates were generally shown to provide a conservative prediction of the ballistic performance of the armor. This approach is promising for the development of a tool for fielded-armor-performance surveillance relying upon mechanical testing of armor coupon samples.
, Leber, D.
, Engelbrecht-Wiggans, A.
, Landais, V.
, Chang, A.
, Guigues, E.
, Messin, G.
and Riley, M.
Linking Theory to Practice: Predicting Ballistic Performance from Mechanical Properties of Aged Body Armor, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/jres.125.026
(Accessed January 22, 2022)