Fatigue Characterization of Composite Laminates with Interface Hybrid Toughening Using a Single-Step Joint Configuration

This study investigates the effect of interface hybrid toughening on the fatigue performance of composite laminates by examining a single-step joint configuration with a bondline incorporating core-shell rubber (CSR) nanoparticles and thermoplastic micro-fiber polyphenylene sulfide (PPS) veils. Three types of bondlines for the single-step joint configuration are produced by resin infusion process: untoughened (i.e. Baseline), single-material toughened (i.e. 10 wt% CSR nanoparticles or 20 g/m² PPS veils) and hybrid toughened (i.e. 10 wt% CSR particles and 20 g/m² PPS veils). High-cycle tension fatigue tests with zero load ratio (i.e. R = 0) are conducted. Backface strain measurements and two-dimensional digital image correlation (2D DIC) are employed to evaluate the initiation and propagation of the crack developed at the untoughened and toughened bondlines. The results show that the hybrid interface toughening method increases the fatigue life (i.e. by ∼49% at low load level and ∼278% at high load level) and reduces crack growth rate, outperforming the untoughened as well as non-hybrid toughened fracture resistance.