Strength Matters: Which Strength of Dyneema® Fiber Composites to Use in Hydrocode Models?—A Discussion

Abstract

Ballistic protective performance of fiber composites correlates highly with fiber tensile strength. The mechanical tensile properties of fibrous UHMWPE cross-ply armor like Dyneema® are a challenge to assess. The reason is the high stiffness and strength combined with low interlaminar shear strength and low friction coefficient. When evaluating the strength of a hard-pressed composite plate using the standard ISO or ASTM dogbone shapes and pneumatic grips an inverse relation of apparent strength to sample thickness is found. This is an artefact of the test not being able to load the whole cross section cooperatively. High quality fiber, yarn and flexible ply tests are possible exploiting the capstan principle. We report typical measurements and discuss which strength to use in hydrocode models.