Dynamic Response of Orthogonal Three-Dimensional Woven Carbon Composite Beams Under Soft Impact

This paper presents an experimental and numerical investigation into the dynamic response of three-dimensional (3D) orthogonal woven carbon composites undergoing soft impact. Composite beams of two different fiber architectures, varying only by the density of through-thickness reinforcement, were centrally impacted by metallic foam projectiles. Using high-speed photography, the center-point back-face deflection was measured as a function of projectile impulse. Qualitative comparisons are made with a similar unidirectional (UD) laminate material. No visible delamination occurred in orthogonal 3D woven samples, and beam failure was caused by tensile fiber fracture at the gripped ends. This contrasts with UD carbon-fiber laminates, which exhibit a combination of widespread delamination and tensile fracture. Post impact clamped-clamped beam bending tests were undertaken across the range of impact velocities tested to investigate any internal damage within the material. Increasing impact velocity caused a reduction of beam stiffness: this phenomenon was more pronounced in composites with a higher density of through-thickness reinforcement. A three-dimensional finite-element modeling strategy is presented and validated, showing excellent agreement with the experiment in terms of back-face deflection and damage mechanisms. The numerical analyses confirm negligible influence from through-thickness reinforcement in regard to back-face deflection, but show significant reductions in delamination damage propagation. Finite-element modeling was used to demonstrate the significant structural enhancements provided by the through-the-thickness (TTT) weave. The contributions to the field made by this research include the characterization of 3D woven composite materials under high-speed soft impact, and the demonstration of how established finite-element modeling methodologies can be applied to the simulation of orthogonal woven textile composite materials undergoing soft-impact loading.