Numerical and experimental investigation on the whirling vibration characteristic of ship propulsion shafting under multi-source uncertainty

Conventional numerical models struggle to accurately capture the whirling vibration characteristics of ship propulsion shafting due to the influence of multi-source uncertainties and gyroscopic effects. Hence, this study develops nonparametric modelling to incorporate multi-source uncertainties into the dynamic equations for shafting. Based on random matrix theory, these uncertainties are represented by random matrices for mass, damping, gyroscopic moment, and stiffness. The whirling frequency under different uncertainties is analysed, revealing that stiffness significantly influences on whirling frequency, followed by mass. Conversely, the gyroscopic moment has the most negligible impact. The range of the first four-order whirling frequencies is estimated accurately using confidence intervals. Additionally, the bearing vibration response is calculated by considering gravity, unbalanced force, and misalignment force. The findings suggest that the time-domain waveform fluctuates within a defined range when considering uncertainty, and unbalance and misalignment are exacerbated, leading to poor stability. Finally, a vibration signal acquisition experiment and modal testing are conducted using a test bench. The experimental results further confirm the effectiveness of nonparametric modelling that considers multi-source uncertainties and gyroscopic effects as more accurate.