Raghupathi , Avula (2009) Dynamic Stability of a Sandwich Plate under Parametric Excitation. MTech thesis.
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Abstract
Vibration control of machines and structures incorporating viscoelastic materials in suitable arrangement is an important aspect of investigation. The use of viscoelastic layers constrained between elastic layers is known to be effective for damping of flexural vibrations of structures over a wide range of frequencies. The energy dissipated in these arrangements is due to shear deformation in the viscoelastic layers, which occurs due to flexural vibration of the structures. Sandwich plate like structures can be used in aircrafts and other applications such as robot arms for effective vibration control. These members may experience parametric instability when subjected to time dependent forces. The theory of dynamic stability of elastic systems deals with the study of vibrations induced by pulsating loads that are parametric with respect to certain forms of deformation.
The purpose of the present work is to investigate the dynamic stability of a three layered symmetric sandwich plate subjected to an end periodic axial force. Equations of motion are derived using finite element method. The regions of instability for simple and combination resonances are established using modified Hsu’s method proposed by Saito and Otomi.
It is observed that for plate with simply supported boundary conditions the fundamental frequency, fundamental buckling load increase with increase in core thickness parameter for higher values of core thickness parameter. The fundamental frequency, fundamental buckling load decrease with increase in core thickness parameter for lower values of core thickness parameter. The system fundamental loss factor increases with increase in thickness ratio. The fundamental buckling load and fundamental frequency increase with increase in shear parameter. The fundamental system loss factor has an increasing tendency with increase in shear parameter. The increase in core thickness ratio and shear parameter has stabilizing effect. Whereas increase in static load factor has a destabilizing effect.
The purpose of the present work is to investigate the dynamic stability of a three layered symmetric sandwich plate subjected to an end periodic axial force. Equations of motion are derived using finite element method. The regions of instability for simple and combination resonances are established using modified Hsu’s method proposed by Saito and Otomi.
It is observed that for plate with simply supported boundary conditions the fundamental frequency, fundamental buckling load increase with increase in core thickness parameter for higher values of core thickness parameter. The fundamental frequency, fundamental buckling load decrease with increase in core thickness parameter for lower values of core thickness parameter. The system fundamental loss factor increases with increase in thickness ratio. The fundamental buckling load and fundamental frequency increase with increase in shear parameter. The fundamental system loss factor has an increasing tendency with increase in shear parameter. The increase in core thickness ratio and shear parameter has stabilizing effect. Whereas increase in static load factor has a destabilizing effect.
| Item Type: | Thesis (MTech) |
|---|---|
| Uncontrolled Keywords: | Parametric excitation, Dynamic stability, Boundary condition, Sandwich plate, simple resonance, combined resonance |
| Subjects: | Engineering and Technology > Mechanical Engineering > Structural Analysis |
| Divisions: | Engineering and Technology > Department of Mechanical Engineering |
| ID Code: | 1457 |
| Deposited By: | Raghupathi Avula |
| Deposited On: | 08 Jun 2009 15:34 |
| Last Modified: | 08 Jun 2009 15:34 |
| Related URLs: | |
| Supervisor(s): | Mohanty, S C |
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