Nonlinear Vibration Analysis Of Elevator Variable Stiffness System

In this paper, the background and significance of the dissertation are introduced, the development trend and the current research situation of dynamic characteristic of elevators in the world are expatiated, and the main research contents of this dissertation are proposed. The research theme of this dissertation is dynamic characteristic of tractive elevator, based on the analysis of the structure of elevators and vertical vibration mechanism of elevators, a dynamics model of vertical direction for tractive elevators is established . According to the trip length and the elevator-timing-curve, the relationship between each moving parameter in course of moving is caculated; thereby makes the foundation of getting the accurated solution of the model.As the car travels to a different location, the length of wire rope on both sides of the traction machine changes, so the stiffness K (that is changed with t) of wire rope changes with the traveling height of the car in the traveling process of the elevator. There is not necessarily closed analytical solution of Time-varying systems. This paper carries on the dynamics analysis by dividing the time varying elevator system into the limited time invariant system, and obtains the vibration displacement,vibration velocity,vibration acceleration of the elevator under the fullload,halfload,unload and upward of work condition by the Matlab software. The analysis gets the conclusion that the change of vibration acceleration of the elevator cabin are bigger in the stage of start-up and brake, the analyzing of influence to the vibration acceleration due to several parameters (acceleration-slope,maximum acceleration etc), it provides references for more study of vibration reducing of the elevator, It also provides the basis for the elevater dynamic characteristic optimization.Based on operating efficiency as the objective function, the value of vibration acceleration is less than a standard as a restrictive conditions, the preliminnary optimization of the change rate of the acceleration and the maximum acceleration of the elevater operating parameters are carried out. This paper discusses the testing technologies of the main vibration parameters briefly, in order to facilitate further in-depth understanding of the lift performance evaluation method. The algorithm and process procedures of this paper are more stringent, reasonable, method and means are the more advanced, the research results have a certain significance to guide the lift production and installation.