Experimental Study of the Influence of pitting and Crack Coexistence in Spur Gear System (Part II)

The dynamic analysis of the influence of pitting and crack coexistence in a two-stage spur gear system is investigated in this experimental study. Gear cracking is one of the main factors causing vibration in gears, and tooth pitting failure is the failure mode of the gear system that can simultaneously occur. An experiment was conducted on a two-stage spur gear test rig to extract and analyse its vibration features. The dynamic responses under variable parameters such as acceleration, frequency, and speed of the gear system behaviour are investigated. Parameter effects revealed a fractional frequency multiplication component and anomalous maximum variation due to the coexistence of pitting and cracking during the experimental test. The Short-Time Fourier Transform (STFT) and Frequency-Revolution Per Minute spectrum provide additional information to understand the influence of the coexistence of pitting and cracking during the engagement of the defective tooth with others. Therefore, the obtained results show the demonstrative power and the sensitivity of the proposed diagnostic technique to detect the gear defects at an operating speed greater than standard Fast Fourier Transform analysis. The STFT and the Frequency-RPM methods have proven effective in extracting and studying the characteristics of pitting and cracking faults in a spur gear system. The analysis results of the experiment showed a qualitative similarity with the obtained numerical results.