Propagation Characteristics of Elastic Waves in Wire Ropes of an Elevator

PurposeThe vibration in an elevator can travels in the form of elastic waves between the elevator car and the traction machine through the wire ropes which connect the two. The vibration signal can help to monitor the statues of the elevator or diagnosis the faults of which. However, the vibration signal may be different with the vibration sources due to the influence of the propagation path. Thus, the vibration measured may be different with the original vibration sources. It's of great necessity and meaning to study the propagation characteristics of the elastic waves in an elevator wire rope.MethodsThe transfer matrix method is used in this study to show how the vibration propagating in the wire ropes. The free-body diagram for a wire rope is performed firstly, and then the motion equation is constructed. Secondly, the wave equations for the elastic waves propagating in elevator ropes is established by using the generalized Hamilton's principle and the transfer matrix method. Finally, a numerical example is illustrated and the pass bands and stopbands of the elastic waves propagating in elevator ropes of different lengths are solved numerically and verified by Finite Element Analysis and related experiments.ResultsThe results demonstrate that a new stopband develops as the length of the elevator rope increases and the width of the existing stopband decreases.ConclusionThe propagation characteristics of elastic waves are affected by the length of the wire ropes. The study can help to reveal how the vibration propagates in the elevator ropes and help for condition monitoring of the elevator traction system.