High cycle fatigue behaviour of autoclave-cured woven carbon fibre-reinforced polymer composite gears

The high cycle fatigue behaviour of autoclave-cured carbon fibre-reinforced polymer (CFRP) composite gears is investigated. The CFRP gears were milled from a composite plate and tested in mesh with a steel drive gear under five torque loads ranging between 0.4 and 0.8 Nm in unlubricated conditions. A detailed gear damage analysis is conducted by employing scanning electron microscopy and high-resolution optical microscopy. Epoxy matrix microcracking is found to be the damage mechanism that leads to the final delamination failure. CFRP gears exhibited a significantly improved performance and a longer fatigue lifespan in comparison with the polymer and polymer composite gears. •Fatigue behaviour of long fibre CFRP composite gears was investigated.•Woven CFRP gears exhibited six times longer lifespan than comparing PEEK gears.•Load-bearing capacity of CFRP gears was 1.75 higher than for PEEK gears.•Fatigue micro-cracks in the epoxy matrix led to epoxy crushing and delamination.•Delamination between plies was the observed failure mode for CFRP gears.