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Title: Vibrations of viscoelastically damped laminated structures
Author: Nakra, Bahadur Chand
ISNI:       0000 0001 3439 3234
Awarding Body: Imperial College London (University of London)
Current Institution: Imperial College London
Date of Award: 1966
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The equations describing the flexural vibrations of a number of configurations of laminated beams, incorporating elastic and viscoelastic laminates, have been derived. Solutions for vibration response have been obtained for the laminated beams, subjected to harmonic excitations and damping action due to strains in viscoelastic layers in each system is evaluated. In general, the solutions are limited to beams with simply supported end conditions, though for the 3 layered configuration, the procedure is outlined for other end conditions also. The theory given for the 3 layered case is applicable to any unsymmetrical configuration, without limitation on the frequency range of application. Detailed analysis of this configuration includes determining the solutions for displacement and stress responses, studying the influence of various geometrical and physical parameters on vibration damping effectiveness of the system, behaviour at high frequencies and the effect of non-linearity due to amplitude dependence of viscoelastic material, properties. Other configurations, with higher number of layers have been analysed, the viscoelastic layers being placed alternately or adjacently. The equations of each system have been programmed on the Atlas digital computer for computations based on the theoretical analysis. The effect of important parameters has been investigated and the applicability of each configuration determined from point of view of increased damping and improved frequency response of the system. Vibration response tests have been carried out on a few samples of laminated beams, in order to verify the results obtained theoretically. Experimental work has also been done to determine the dynamic properties in shear, of a few viscoelastic materials, including those used in making the laminated beams for vibration response tests.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available