Analysis On Steady-state Response Of Blade Structure With Rubbing Faults

High-speed rotating blade is the key component of rotating machinery, widely used in the aerospace and mechanical engineering fields. The blade with high rotating speed mainly loads on the unstable gas excitation force and centrifugal force generated by high speed rotation. The rubbing between blade and casing is one of the most common faults for air compressor set, which generally makes the rotating blades have a greater amplitude vibration and causes the system to produce a very complex nonlinear dynamical behavior. Besides, the rubbing will also make the blades a series of serious failure behaviors, fatigue, bending and fracture, etc., which affect the safe and stable operation of the set. The topic takes the blade of turbine air compressor as the research object, studied the nonlinear dynamic characteristics of rubbing blade structure from the theoretical and numerical, and analyzed the steady-state response.As one of the quantitative methods for solving nonlinear vibration problems, the incremental harmonic balance method has been widely applied in the various fields of nonlinear vibration, and become an effective method for nonlinear vibration, especially for strongly nonlinear vibration. However, it is time-consuming for solving the complete multi-degree of freedom and localized nonlinear system steady-state response, which greatly limits its application in the analysis on high dimensional and localized nonlinear system. Therefore, aiming at the nonlinear characteristics of nonlinear and localized multi-degree of freedom system, caused by rubbing, dimensionality reduction incremental harmonic balance method (DRIHB) is proposed by Yao Hongliang. The main contents of this paper and results are as follows:Firstly, based on the incremental harmonic balance method, the dimensionality reduction incremental harmonic balance method (DRIHB) is presented. Through harmonic balance theory, quantitative comparison relationship of each degree of freedom and each harmonic in the system is analyzed, and that makes the dimension of the system have the same number of degrees of freedom of nonlinear. Since the dimensionality reduction system is a plural system, this paper presents a method for solving such system, as well as the reduction method of each degree of freedom and each order response of the original system.Secondly, using this algorithm, the steady-state periodic solution of rubbing faults system of plate structure and blade structure are calculated, and the time domain waveform and spectrum of the compared results are drawn. Through comparison with the results of numerical integrated methods, the accuracy and timeliness of the algorithm are verified. Besides, the harmonic response curves are directly drawn by using this algorithm. The advantages of the algorithm in the analysis of complex high dimensional nonlinear vibration problems are also reflected.Thirdly, the finite element dynamic model of the large air compressor’s rotor system is established, and such complex high-dimensional strongly nonlinear vibration problems of rotor system are studied. The steady-state responses of the rubbing blades are analyzed in three rubbing positions of one rubbing position, two rubbing positions and four rubbing positions. And then the influence of rubbing stiffness and rubbing clearance on the system’s response are analyzed.