Experimental characterization and numerical modelling of the translaminar fracture of woven-ply hybrid fibers reinforced thermoplastic laminates. (December 2022) - Bouvet, C.
Graphical abstract: Numerical modelling of the axial strain distribution near the crack tip in 0/90° plies and ±45° plies at different stages of the crack propagation in 45° Single Edge Notched bending specimens. Highlights: This study provides information on the fracture toughness values to design thermoplastic-based composite parts. The evolutions of cracks lengths show the contribution of tensile and compressive failures on macroscopic fracture. A Finite Element mesoscale model was built to account for the plastic deformation mechanism and the different damages. Half of the energy is dissipated by fiber failure and one-half by local plastic deformations or compression crushing. Abstract: The understanding of fracture mechanisms and the assessment of fracture toughness are key factors to the design of high-performance composite structures to be used in aeronautics. Thus, this work addresses the influence of initial notch orientation on the translaminar fracture of woven-ply hybrid fibers reinforced thermoplastic polyether ether ketone (PEEK) laminates. The translaminar fracture of Single-edge-notch bending (SENB) specimens is experimentally characterized depending on two initial notches (0° and 45°). Such geometry results in a complex stress state within the laminates plies as well as simultaneous tension/compression failures. A full-field measurement technique has been implemented to monitor the crack initiation and growth on the specimen surface during mechanical loading. To better understand the role played by the initial notch orientation as well as the plies orientation contribution to fracture behavior, a specific Finite Element mesoscale model was built to account for the deformation mechanisms (namely local plasticity) and the different damage behaviours (fiber breakage in tension and compression, kinking/crushing in compression, delamination) occurring within the plies of quasi-isotropic laminates. Linear elastic fracture mechanics concepts have been applied to quantify the critical translaminar fracture toughness (about 40 kJ/m 2 in both cases). Finally, this study provides useful information on the fracture toughness values for engineers willing to design thermoplastic-based composite parts with stress concentrators.