The gearbox transmission system of large-scale heavy-duty equipment often works under complex working conditions such as heavy load, impact and variable load, and its core components are prone to damaging single and composite faults such as spalling, cracking and even fracture.Therefore, in-depth study of gear vibration mechanism, signal characteristics and fault diagnosis methods are of great significance.

Recently, a research team launched a study on the coupling mechanism of compound faults in heavy-duty gearboxes under complex working conditions and multi-source excitation.With dynamic expansion and wavelet finite element and centralized parameter method as technical means, they established a multi-degree-of-freedom coupled dynamics model of scalable gearbox with composite faults, and studied the coupling factors and numerical solution algorithms as well as the dynamic response under the excitation of multi-dynamic parameters.

Through experimental and theoretical analysis, the team found that gears have unique vibration response characteristics and signal features under different fault states.For example, in the bearing damaging composite faults, the nonlinear coupled dynamics model of rolling bearing composite faults established by comprehensively considering the ball slip, oil film stiffness and bearing nonlinear time-varying stiffness can accurately analyze the vibration response characteristics of bearings under single faults of each component and composite faults of inner and outer rings.

Based on these research results, they proposed a series of fault diagnosis methods, such as the composite fault coupling feature separation and extraction method based on the composite dictionary multi-atom matching technology, as well as the adaptive noise reduction technology based on the frequency domain statistical test theory and advanced time-frequency synthesized signal processing methods, etc., which provide powerful technical support for the fault diagnosis of heavy-duty gearboxes.