Modelling of fatigue crack tunneling and delamination in layered composites

A review of the literature reveals that fatigue cracks in layered composites may grow at a constant rate in a steady-state configuration. Cracks can tunnel as mode I cracks in a constrained layer, with or without delamination of adjacent plies. Alternatively, progressive plane-strain delamination may occur from the ends of a plane-strain mode I crack. In the present paper the relationship between fatigue crack growth rate and remote cyclic stress is predicted for steady-state tunneling cracks and for plane-strain delaminating cracks. The fatigue models make use of Paris-type crack growth laws. The predictions for plane-strain delamination are in excellent agreement with existing experimental data for fatigue delamination growth in fibre–metal laminates.