PREDICTION OF DYNAMIC CHARACTERISTICS OF VIBRATING STRUCTURE WITH UNCERTAIN PARAMETERS

Imran Ahemad Khan, G. K Awari

Abstract


This paper is based on a study of vibrational responses of different vibrating systems with uncertain parameters. The concept of uncertainty plays an important role in the design of the practical mechanical system. So it becomes important to study its effects on the mechanical system. A large and varied amount of research has been dedicated to developing techniques which predict the dynamic responses of structures in all frequency domains and structures with uncertainty. The structural element selected in this work is the plate. The plate is considered in terms of mass, stiffness and a combination of mass and stiffness uncertainty. The dynamic characteristic of the plate with all uncertain parameters is found by using the Finite Element Method. In this paper modal and harmonic analysis of the plate is done. In modal analysis the natural frequencies and mode shapes of the plate are found. The response of a bare plate is compared with plates for which different uncertain parameters are considered. Similarly, in harmonic analysis the frequency response function of the bare plate and the plates with all uncertain parameters are compared. During comparison, it was found that due to mass uncertainty minor changes in the natural frequency and in mode shape were obtained. However, due to stiffness the natural frequency, mode shape and FRF were drastically changed. Similarly, due to a combination of mass and stiffness uncertainty drastic changes were observed in the plate response. Because of these uncertainties the complete vibrational characteristics were changed. So it becomes important to consider these uncertainties to avoid misinterpretation while designing plates.
 
Keywords: Uncertain Parameters; vibration analysis; modal analysis; harmonic analysis; FEM.

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