A NONLINEAR DYNAMIC ANALYSIS FINITE ELEMENT PROGRAM WITH AN APPLICATION TO ELEVATOR COUNTERWEIGHT SYSTEMS
Abstract
A general purpose nonlinear dynamic analysis finite element program is developed. The eigenvalue analysis of linear systems and the time-domain integration of linear or nonlinear systems can be performed for the systems modeled by beam elements. The program has the capability of analyzing an elastic system in which there is contact between parts of the system. One application of this program is the study of nonlinear dynamic response of elevator counterweight/frame/guide rail systems subjected to external base excitation. A simplified small-scale physical model has been built and tested to study its dynamic behavior. Several finite element models corresponding to the experimental model and to full-scale systems are constructed to evaluate the methodology, study the nonlinear response, and validate the program. Systems with viscoelastic dampers which are modeled by Standard Linear Model of viscoelastic material have been evaluated. The results show that a large dynamic contact load may occur with current design practice. The contact load can be reduced by 40% when the intermediate tie is applied in the system. This tie also prevents the disengagement of roller guides. The introduction of a large gap between the counterweights and their frame can increase the loading if the input motion exceeds the gap. The introduction of rubber dampers may reduce the load by 84% as compared to current design practice. A simple design formula can be used to estimate the required damper stiffness by using the design gap, the weights, and the excitation amplitude and frequency.
Degree
Ph.D.
Subject Area
Mechanical engineering
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