On the investigation of quasi-static crack resistance of thermoplastic tape layered composites with multiple delaminations: Approaches for quantification

The present study is devoted to the quantitative characterisation of the interlayer bonding in unidirectional carbon fibre reinforced thermoplastic laminates produced by automated tape placement with in-situ consolidation (ATPisc). Two different manufacturing protocols were applied to produce the laminates that were further characterised using the quasi-static mode I double cantilever beam (DCB) test. Regardless of the manufacturing approach, the laminates exhibited multiple cracking accompanied by fibre bridging during testing, which affected the main mid-plane crack propagation. This effect was examined by comparing the crack length visually measured during testing with both the crack length back-calculated from the compliance and the crack length calculated using the flexural modulus and the compliance. In addition, the investigation of the evolution of the effective flexural modulus E1 and the damage parameter phi throughout testing was performed for a better understanding of the damage accumulation in the specimens.

Automated summary

The study focused on quantitatively characterizing the interlayer bonding in unidirectional carbon fiber reinforced thermoplastic laminates produced by ATPisc. The laminates exhibited multiple cracking with fiber bridging during testing, affecting the main mid-plane crack propagation. Comparisons were made between visually measured crack length, back-calculated crack length, and crack length calculated using flexural modulus and compliance, to study this effect, along with investigating the evolution of effective flexural modulus and damage parameter throughout testing.