Fatigue crack growth properties of carbon-polyamide 6 thermoplastic composites using a multi-ΔG control method

•A new multi-ΔG control approach to perform mode I fatigue crack growth under constant ΔG is presented.•The crack propagation behaviour can be accurately described using the Hartman-Shijves equation.•First results concerning the fatigue crack growth behaviour of C/PA6 composites are presented. The present paper presents a new multi-ΔG control approach to perform mode I fatigue crack growth tests using several constant cyclic energy release rate ranges (ΔG) on only one specimen. It was successfully applied on carbon/polyamide 6 unidirectional composite specimens. After validation checks on the approach, results show that the crack propagation behaviour exhibits three different crack propagation regimes that can be accurately described using the Hartman-Shijves equation. This work has shown that the multi-ΔG control method can provide reliable crack growth propagation results and a complete ΔG versus cycles description.