Vibration and Flutter Analysis of Sandwich Shells and Plates with Fractional Viscoelastic Core

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Permoon, Mohammad Reza | 2021

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Type of Document: Ph.D. Dissertation
Language: Farsi
Document No: 54687 (45)
University: Sharif University of Technology
Department: Aerospace Engineering
Advisor(s): Hadadpour, Hassan
Abstract:
The vibration and flutter characteristics of sandwich shells and plates with constrained viscoelastic layer are presented. The mechanical properties of viscoelastic core is modeled using fractional order model and the thin shells theory has been used to obtain the structural equations of the outer layers. Linear piston theory has also been used for aerodynamic modeling. The equations governing the vibrations and flutter of shells and plates are obtained using Newton method and in some cases using the energy method. The Rayleigh-Ritz method is implemented to solve the discretized governing equations for linear examples and the method of multiple scales is used to solve the nonlinear ordinary differential equations. The results are compared with other investigations and the effects of variation of the governing parameters such as length to radius, radius to thickness and core to facing thickness on the stability margins, fundamental frequencies and loss factors are investigated and some conclusions are outlined
Keywords:
Flutter ; Constrained Layer Damping (CLD) ; Fractional Viscoelastic Material ; Fractional Derivative ; Vibrational Analysis ; Rayleigh-Ritz Method