Aged and unaged flexible unidirectional composite laminate tensile testing for soft body armor applications

Flexible Unidirectional (UD) composite laminates are commonly being used for ballistic-resistant body armor. These laminates comprise UD layers, each constructed by laminating thin layers of high-performance fibers held in place using binder resins, with the fibers in each layer oriented parallel to each other. As these materials are used in body armor, it is important to investigate their long-term reliability, particularly with regards to exposure to temperature and humidity as these are known causes of degradation in other commonly used body armor materials. This work investigates the tensile behavior of a poly(p-phenylene terephthalamide), reffered to as PPTA, flexible UD laminate, both unaged and aged for up to 150 d at accelerated conditions of 70 °C and 76 % relative humidity (RH). Tests on aged specimens were performed at three different crosshead displacement rates and three different gauge lengths. Unaged characterization additionally included three different widths and two other configurations.