Impacts and Waves in Dyneema® HB80 Strips and Laminates

Abstract

Single-yarn impact results have been reported by multiple authors in the past, providing insight on the fundamental physics involved in fabric impact. This insight allowed developing full fabric models that were able to reproduce properly wave propagation, deflection, and ballistic limits. This paper proposes a similar experimental methodology but for a specific composite material made of ultra-high molecular weight polyethylene. The presence of the polyurethane matrix in the composite is expected to slow down wave propagation. But the high-speed photographic tests reported in this paper indicate that wave propagation in strips and single-layer material is similar to that expected for dry fiber. An explanation is proposed for this unexpected result. This paper also reports the critical velocities (i.e., impact velocities that fail the fibers immediately) measured for the composite material and compares them to the velocities expected from the theory. The velocity is accurately predicted when taking into account wave interactions in front of the projectile. Finally, tests on multilayer composites are presented. In particular, a flash produced under the projectile during the first few microseconds was recorded with high-speed video cameras. A simplified study of the temperature increment upon impact indicates that the material may be reaching the autoignition point. This mechanism is speculated to be the origin of the flash systematically observed.

Transitioning a unidirectional composite computer model from mesoscale to continuum

“…Transverse wave speeds measured in [6] agree reasonably well with the ones measured in the numerical simulations for single layers.…”

“…Transverse impact simulations on the strip were performed at different velocities to check the strain, the transverse wave velocity, and the critical velocity (impact velocity that fails immediately the fibers). These were compared to the predictions from theory and the tests performed in [6]. The results were very satisfactory as shown in [3].…”

“…The first step to create the UD model was to reproduce the ballistic impact results presented in Chocron et al [6] for single-layer/single-ply and for single-layer/three-plies (90/0/90, where the 0 direction is on the length direction of the strip. )…”

Yarn-Level Modelling of Woven and Unidirectional Thermoplastic Composite Materials Under Ballistic Impact

“…The first type of panel was made of single layers of Dyneema manufactured by DSM (Netherlands) is a (0/90) 2 lay-up composed of approximately 84% fibres (in weight) and 16% polyurethane matrix [27]. Ultra-highmolecular-weight polyethylene (UHMWPE) [28] fibres SK76 are used for prepregs [29].…”

Mechanisms of Dynamic Deformation and Failure in Ultra-High Molecular Weight Polyethylene Fiber-Polymer Matrix Composites

“…The performance is dependent upon the composite architecture as well as fiber and (to lesser extent) matrix properties [26,[30][31][32][33]. The focus of much research therefore has been in exploring the mechanisms responsible for projectile penetration in the velocity regime below where hydrodynamic effects dominate [22,30,[34][35][36][37][38][39]. Such measurements have been used to develop continuum models (e.g.…”