Theoretic And Test Research On Dynamic Behaviors Of High-Speed Elevator Suspended System

Today, elevators, as a kind of vehicles for vertical transportation, play an important role in the life of common people. More and more high-rise buildings and elevators come forth in the city now. With the developments of elevator drive techniques, the hoisting height and velocity of elevator increase. However, the severer requirements about security and comfort of elevator are brought forward with these increases. In order to solve this conflict, the dynamic capabilities of elevator suspended system must be comprehended.The suspended system of traction elevator is composed of sheave, steel rope, car/counterweight and so on. In this system, the traction rope's behavior of hoisting directly comes from the friction force between rope and groove of sheave. And the motion of car or counterweight is pulled by traction steel rope. According to the capabilities of flexible system, while it is moving, the complicated dynamic behaviors may be excitated by elastic vibration of elevator system. Especially, when the velocity of elevator system arrives to a high value, or the outside interferences exists, these complicated local or whole dynamic behaviors may bring some considerable influences to the security and comfort of elevator.In this paper, the used research methods include theoretic analysis and realistic test. The start and the termination of this research are the run security and ride comfort of elevator. The local dynamic behaviors and the whole dynamic behaviors both are discussed and reproduced by theoretic equations and test model. The causes and effects of abnormal vibration or dynamic instability during the trip of elevator are analysis.In the aspect of ride comfort, the dynamic behaviors of elevator flexible suspended system are paid attention to. The suspended system is abstracted and considered as a kind of taut translating strings with a mass attached at its low end. The theory of elasticity mechanics is used to build the distributing theoretic model (including the vibration governing equations and energy equations) of coupled transverse-longitudinal vibration of flexible suspended system. To obtain the numerical solves, these equations are spatially discretized. Refer to the elevator suspended system, an experimental model for dynamic capability of flexible suspended is designed and built. To compare the simulation results and the experimental results, the validity of the theoretic model is affirmed. Then, the dynamic behaviors of flexible suspended system of high-speed elevator and its influence facts are simulated and discussed. According to the simulation results, the abnormal vibrations often occur during the upward trip of high-rise elevator, which may bring bad influences to ride comfort. At last, the lateral vibration responses of elevator car arising by the uneven surface of guide rail are researched. According to the simulation results, the lateral vibration of car may be affected by flexible characteristics of system and guide rail together.In the aspect of run security, the traction capability of elevator suspended system is paid attention to. An experimental and analysis method is introduced and implemented to obtain the friction coefficient between traction rope and groove of sheave. The relationship between friction coefficient and tension, angle of wrap, shape of groove, lubrication, fatigue are discussed, respectively. Then, the theory of multi-body system dynamics is used to build a discrete model to simulate that the traction rope wraps in the groove of sheave. This model can be used to research the local dynamic behavior between rope and sheave, for example, contact, slippage and off-track. Comparing with the test results, which are from the actual elevator system, the simulation results of theoretic model is reasonable.In this paper, the typical dynamic behaviors of elevator suspended system are discussed and researched by theoretic and experimental methods. The reasons, phenomena and effects of these dynamic behaviors are simulated and analyzed. The basic principles of traction capability and coupled vibration of elevator are reproduced and explained. All of these results will be beneficial to the intending theoretic research of elevator suspended system. At the same time, they provide some useful ideas and means for the next research about vibration suppression and control.