Coupled axial-lateral-torsional stochastic dynamics of a rotor-bearing system subjected to periodic pulse and unbalanced excitations

In rotor-bearing systems, the coupling effects between axial, lateral, and torsional vibrations have a significant impact on dynamic characteristics, which become even more complex under unsteady excitation conditions. This study investigates the stochastic axial-lateral-torsional coupled vibration of a pulse detonation engine rotor system subjected to combined periodic pulse and unbalanced excitations. By considering key uncertainties such as geometric deviations, material properties, and assembly tolerances, this work offers a comprehensive analysis of the dynamic characteristics and the uncertainty propagation mechanisms of pulse detonation engine rotor system for the first time. To address the challenges posed by high-dimensional and strongly coupled effect, a non-intrusive hybrid surrogate model polynomial chaos-Kriging is developed. The model effectively characterizes the complex relationship between uncertain inputs and system coupled responses, and significantly improves the efficiency and accuracy of uncertainty quantification. The analysis encompasses modal responses, transient responses during the startup phase, and steady-state behaviors during constant speed operation. The global sensitivity analysis is performed to identify the influence of various structural parameters on different response modes. The results reveal that the system exhibits distinct sensitivity to bearing properties, geometric dimensions, material properties, and excitation amplitudes under different operating conditions. This study not only enhances the understanding of the coupled dynamic mechanisms in pulse detonation engine rotor systems but also provides a theoretical foundation and modeling framework for structural design, performance optimization, and reliability improvement.