Phenomenological modeling of planetary gear trains considering corner contact meshing impact with different fault size

Studying the vibrational generation mechanisms of planetary gear train (PGT) plays a vital role in monitoring its health conditions. The meshing stiffness is an important influencing factor for the generated vibrations. Due to the actual meshing line often not being aligned with the theoretical one, the corner contact phenomenon occurs during the meshing process, which leads to the generation of relative velocities along the meshing line, resulting in meshing impacts. Under fault states, the vibration caused by these impacts is more significant, with the impact forces varying according to the size of the fault. Previous phenomenological models fail to delineate the vibration characteristics under diverse fault sizes and local fault impulse. This study investigated the meshing stiffness and impact of PGT under both normal and malfunctioning conditions and developed a periodic meshing impact function. The relationship between fault impacts and the meshing process was analyzed, leading to the development of an improved vibration signal model capable of reflecting fault size. Simulation studies are carried out to compare the patterns of sideband distribution under three different sizes of sun gear crack faults. The results indicate that as the fault size increases, the amplitude of the sidebands around the meshing frequency increases significantly, while the amplitude of the meshing frequency changes slightly, which phenomenon is also validated experimentally. The experimental studies demonstrated that the proposed model has a superior ability to characterize the vibrations compared to the conventional model.