Braided textile composites for sports protection: Energy absorption and delamination in impact modelling

Composites reinforced with braided textiles exhibit high structural stability and excellent damage tolerance, making them ideal materials for use in sports-protection equipment. In sports impact scenarios, braided composites need to maintain their structure integrity and dissipate impact energy to protect a human body. Thus, it is crucial to study the dynamic response of a composite structure and its energy-dissipation mechanisms. Here, a multi-scale computational approach was explored to capture main damage modes of a braided textile composite; simulations were supported by experimental verification. A drop-weight test was performed with a spike-shape impactor to imitate real-life sports impact collision scenarios, followed by X-ray computed micro-tomography to characterize damage morphology of the specimen. The experimental results were compared with analytical models. The extent of delamination was quantified by applying surface- and element-based cohesive zone models. A ply-level model with three-dimensional continuum and shell elements was employed to explore the effect of through-thickness failure modes on energy absorption of the composite. The propagation mechanism of matrix cracks is also discussed. In addition, with the developed model, impact-attenuation performance of a shin-guard structure was simulated. The presented modelling capability can improve design of braided composite structures for sports and other protective and structural applications.