Mesoscale ballistic damage mechanisms of a single-layer woven glass/epoxy composite

Understanding damage mechanics across multiple length scales is necessary for design of enhanced protection by composite armor systems. In this work, we investigated the perforation mechanics of a single layer, woven composite target transversely impacted below and above the ballistic limit by a rigid projectile sized on the order of a tow width. To visualize mesoscale damage mechanisms of woven composites, a thin translucent composite target was used providing access to both impact and back-face surfaces. High-speed video, high-speed digital image correlation, high-resolution photography, and X-ray computed tomography were used to gather data. Impact and residual velocity data, ballistic limit velocity, and projectile impact location relative to the weaving architecture were quantified. It was found that impact on a tow-tow crossover requires more energy to perforate than impact on a matrix-rich interstitial site or on adjacent, parallel tows. Dynamic deflection and the transverse deformation cone wave-front velocity of the thin composite were measured. Meso-mechanical damage in thin, woven composites was characterized for impact velocities below and above the ballistic limit. Four mesoscale damage modes were identified: transverse tow cracks, tow-tow delamination, 45° matrix cracks, and punch-shear. These damage modes were observed both on the surface and inside the composites. The data presented here are useful for mesoscale modeling of woven composites, and this work provides new insight into meso‑mechanical modes of damage in thin composite structures under dynamic impact.