Dynamic asymmetrical instability of elastic–plastic beams |
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Authors: | GW Ma YM Liu J Zhao QM Li |
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Affiliation: | aSchool of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798;bSchool of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Pariser Building, P.O. Box 88, Manchester M60 1QD, UK |
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Abstract: | Dynamic instability of elastic–plastic beam is investigated by employing a three-degree-of-freedom (3-DoF) beam model. Especially, asymmetrical instability induced by symmetrical load is discussed. The asymmetrical instability is considered as a second-order buckling mode. Four types of perturbations, i.e., geometrical misalignment, material property mismatch, unsymmetry of applied load and disturbance of boundary conditions, are introduced to activate the asymmetrical responses. The asymmetrical response is characterized by a modal participation factor α2 which corresponds to an asymmetrical mode shape. Phase plane trajectories and Poincaré map are used to illustrate the chaotic characteristics of the beam response. Results show that if the perturbations are small enough, the perturbation type has negligible influence on the critical load for the occurrence of the asymmetrical instability, which implies that the asymmetrical instability is an intrinsic feature of the beam system. However, with the increase of the magnitude of the perturbations, the influence of the asymmetrical vibration is expanded to a large extension of loading parameter. |
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Keywords: | Dynamic instability Asymmetrical response Elastic– plastic beam Impulsive load Geometrical misalignment Material property mismatch Unsymmetry of applied loads Disturbance of boundary conditions |
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