Research On Uncertainty Of Rotor System Based On Polynomial Chaos Expansion

The rotor has always been an important part of the aerospace industry,and its good operation is directly related to the performance of the engine.In order to ensure good dynamic performance of the rotor,it is required to have high precision and stability.However,various uncertain factors will occur in the actual situation,which will have a great impact on its dynamic characteristics.Therefore,it has a strong practical significance to study the uncertainty problems.In this paper,the vibration expression of polynomial chaos expansion method in single-degree-freedom system and multi-degree-freedom system is studied.The polynomial modeling process is analyzed in detail,which is helpful for the application of the rotor system later.Then combined with rotor dynamic knowledge,the theory is applied to the double-disc rotor system,and the results are compared with the Monte Carlo method.The results show that the polynomial chaos expansion method has good applicability in solving the uncertainty of the rotor system.Then,combined with polynomial chaos model and Sobol sensitivity analysis method,the parameter sensitivity analysis method of rotor critical speed is proposed.The results show that the method can reflect the sensitivity of rotor critical speed to various uncertain parameters quickly and accurately.At the same time,it can be both accurate and efficient.On this basis,a reasonable finite element model is applied to the actual turbine pump rotor system to abtain a suitable finite element model.The uncertainty of the joint stiffness caused by the uncertainty of the preload force in the middle part is taken as the uncertainty variable.Then the uncertainty of the rotor dynamic is analyzed by the polynomial chaos expansion method.The results show that the uncertainty will have a great impact on the area near the second-order critical speed of the rotor.As the uncertainty spreads,the degree of local stiffiness will be different.