Experimental investigation of damage transition in thermoplastic composites at the microscale

Thermoplastic composites become very popular for making impact-prone structures. An efficient approach to estimate the out-of-plane mechanical performance of thermoplastic composites is proposed to support the material development stage as well as modeling approach. The estimation was done by isolating the principal damage modes in a relatively small sample subjected to three-point bending (3PB) load within micro-tensile/compression stage (Kammrath & Weiss). The in situ damage development, i.e. the transition from transverse crack to delamination, was recorded by scanning electron microscope. Two loading speeds were evaluated, e.g., 0.5 micron/sec and 20 micron/sec, in relation with the absorbed energy. The role of fibrillation in the wake of crack bridging is discussed.