Quantitative investigations on multi-layer interface debonding behaviors for sisal fiber reinforced composites using acoustic emission and finite element method

Complete interfacial performances of sisal fiber (a typical plant fiber) reinforced composites (SFRCs) during the single fiber pull-out experiments were investigated experimentally with numerical simulation in the present study. The single SFRCs were found to present three-interface failure. The failure behaviors of the three interfaces were characterized by in-situ acoustic emission technique and identified as interfacial failure between technical fiber and matrix, that between elementary fibers and that between micro-fibrils of cell walls using microscope observation. Statistical analysis was employed to evaluate pull-out probability of technical fiber, elementary fibers and micro-fibrils. The embedded fiber length was concluded to dominate the failure modes of SFRCs. To further gain insight in the complete failure processes and mechanisms of the multi-layer SFRCs, a triple-interface finite element model was developed based on the cohesive zone law. Quantitative comparisons of applied stress between numerical predictions and experimental results surmised that the triple-interface model could accurately describe the multi-stage pull-out behaviors of the single SFRCs.