Fatigue behaviour of thermoplastic glass/polypropylene composite cross-ply laminates: An experimental study with in-situ damage observations and numerical validation

In-situ fatigue damage quantification in non-transparent thermoplastic composites is cumbersome, however, it provides vital information for developing reliable fatigue damage models. This study investigates the tension -tension fatigue behaviour of Glass/Polypropylene laminates. The mechanical response and damage progres-sion in [02/902]s , [902/02]s and [0/90]2s lay-ups are characterized over 500 000 cycles. Microscopic analyses and through-the-width sectioning are considered to compare detected edge cracks to the internal damage state. Effects of ply thickness and location as well as fabrication-induced morphology on fatigue response are inves-tigated. Normalized stiffness reduction and Poisson's ratio evolution in function of measured crack density are compared with numerical results showing good agreements.