Improved Transfer Path Effect Model Considering Frequency Attenuation for Planetary Gear Train With Sun Gear Fault

In the vibration signal model of a planetary gear train (PGT), the transmission path effect is a crucial factor for the interpretation and understanding of its modulation mechanisms. Due to the unique structure of the PGT, it has multiple transmission paths, whose length changes over one rotation cycle, making the modulation even more complicated. Previous models have included the time-variant transmission path influence but ignored the fact that different frequencies of the vibration signal attenuate differently. Therefore, this paper constructs a novel transmission path effect function that takes into account the lengths of the signal transmission path, as well as the influence of frequency attenuation on the signal transmission. Moreover, an excitation force function incorporating rotational speed fluctuations was derived by employing Fourier series to simulate rotational speed fluctuations. Simulation studies are carried out to compare the improved vibration model with previous ones, showing that the proposed model not only reflects the meshing frequency and its sidebands but also reveals the fault characteristic frequencies and its sidebands. Finally, experimental results show that the spectrum distribution pattern of the proposed model corresponds more closely to that of the experimental signal, further confirming the validity of the proposed model.