Numerical and experimental analyses of the fatigue threshold of composite bonded joints under pure mode I loading

The determination of fatigue threshold in carbon-epoxy bonded joints under mode I loading was addressed in this work. The Double Cantilever Beam setup was used to carry out five experimental fatigue tests under displacement control. An equivalent crack length-based procedure was employed to obtain the development of strain energy release rate (SERR) with the number of cycles. The modified Paris law parameters and the corresponding SERR fatigue threshold were obtained for this set of specimens. A high-cycle fatigue cohesive zone model relying on the modified Paris law and accounting for SERR fatigue threshold was developed. The model was initially validated by a numerical benchmark case and then applied in the context of the current analysis. The robustness of the numerical model to address the fatigue threshold under mode I loading was confirmed by comparing the results against experimental ones.