Oblique ballistic impact into fiber-based composites has not been a topic for intensive research thus far, but recently is receiving more attention in applications.
In this presentation, we want to present the results of experimental investigations and numerical simulations on oblique impact of two projectiles (flat right circular cylinder (RCC) and a steel sphere into laminate targets, consisting of multiple, cross-plied sheets of UHMWPE fiber in differentcpolymer matrices at 10-20% mass fraction. Laminate targets were produced from the same fiber, but in a soft (S) and in a hard (H) matrix, and additionally in unpressed (U) and pressed (P) condition, where in the latter, the 4-ply sheets where to bonded to each other, but not in the former.
Ballistic tests were conducted both under normal (N) and 30° oblique (O) impact to determine both V50 and the development of depth-of-penetration as a function of projectile impact velocity.
In order to be able to simulate the observed experimental observations, a numerical model was developed using fiber-based, uni-directional laminate layers, stacked onto each other in a 0°/90° alternating manner. The simulation model embodied a large array of coupled mass-spring-damper yarn and matrix elements, arranged to mimic the laminate target geometric structure, the different matrix stiffnesses and different consolidation conditions, and including frictional slip for the projectile and sheet onto sheet.
The phenomena revealed by the numerical simulations enable good physical insight into the
different mechanisms leading to deviant ballistic behaviour upon oblique impact onto fiber-based laminate targets and how they depend on the detailed laminate properties.