Research On Response Surface Method Of Complex Dynamics Characteristics Of Rotor System

The rotor system is an important part of aircraft engine. How to find out the key factors of rotor dynamic response characteristics quickly and efficiently and design the structure meeting the requirements is the major research direction in the field of rotor dynamics for experts and scholars in aviation area nowadays.Aiming at the rotor dynamics problem of long solving time and large scale computation, the response surface method has been introduced into solving the dynamic response characteristics of rotor system. Through combining the finite element method with design of experiments and function fitting, the response surface analysis of rotor critical speed characteristics and thermal-structural coupling dynamic response of blade-to-case rub-impact were accomplished. The specific research content is summarized as follows:(1) Currently common methods and its characteristics were concluded by the investigation on the theoretical basis and present research situation of RSM. It was benefit for selecting suitable sampling spot filter criteria and response surface function fitting method. Also it was a preparation for response surface analysis of rotor dynamic characteristics and coupled thermal-structural dynamic response of blade-to-case rub-impact.(2) Through introducing the RSM into solving the critical speed characteristics of rotor system, the complicated FEM model of the rotor system with more degrees of freedom could be substituted by response surface model, and a new method was acquired for solving rotor critical speed with changing shaft diameters. Taking the main structural parameters of rotor system as design variables and the rotor critical speed as response value, the response surface model of rotor critical speed is established with the design of experiments and function fitting. Through the sensitivity analysis of rotor critical speed characteristics, the impact of main factors on rotor critical speed was accomplished.(3) The analysis method and procedure of frictional coupled thermal-structural field were studied. A thermal structural coupling finite element model of blade-to-case was established according to the Fourier heat conduction equation in rotating coordinate system. The study on transient frictional coupled thermal-structural dynamic response characteristics was conducted by the direct coupled method. Compared to the result without considering the effect of temperature load, the temperature load had obvious effect on the stress distribution of blade-to-case. So the friction thermal effect should not be ignored in the process of rotor-stator rub-impact.(4) Establish the response surface method of transient frictional coupled thermal-structural dynamic response characteristics. A response surface analysis technique for blade-to-case coupled thermal-structural dynamic characteristics was proposed. Setting the certain centrifugal force, friction coefficient and rotate speed of the blade as design variables, the stress trend of blade-to-case with these factors is analyzed by response surface method when the temperature taking into account.