Early contact fatigue evaluation of gear using eddy current pulsed thermography

One of the most common gear damages is contact fatigue damage, which is difficult to be detected at an early stage. As one of the integrative non-destructive testing and evaluation techniques (NDTE) of eddy current and thermography, eddy current pulsed thermography (ECPT) has been applied for fatigue damage characterization. However, quantitative material state characterization before microcrack initiation do not be solved completely in previous work of ECPT. In this paper, the heat flow can be tracked by using optical flow method and the transient thermal behaviour among areas where the gear flank is suffered contact fatigue and not suffered contact fatigue is evaluated. The degree of fatigue is quantified across a thermal image sequence. The relationship among optical flow, the transient thermal behavior and microstructure of gear fatigue at an early stage is established. The results show that the fatigue damage of gear can be well evaluated by using this method.