Multi-layer orthotropic finite cylindrical shells with a viscoelastic core in contact with fluids are gaining increasing importance in engineering. Vibrational control of these structures is essential at higher modes. In this study, an extended version of the wave propagation approach using first-order shear deformation theory of shell motion is employed to examine the free vibration of damped ...

This tutorial examines the nature of natural frequencies and damping ratios for systems with nonproportional damping from first principles. Computational schemes are discussed for the numerical determination of complex eigenvalues. A common misunderstanding of the nature of the natural frequency of a nonproportionally damped system is discussed and illustrated through numerical simulations. 1 ....

ABSTRACT: An efficient method is proposed to find optimal design of arch dams on the basis of constrained natural frequencies utilizing continuous evolutionary algorithm. To extract natural frequencies of arch dam considering fluid-structure interaction, it is necessary to solve the unsymmetrical damped eigenproblem. This means that the process of natural frequencies extraction may impose much ...

Abstract This paper presents a method to analyze the free vibration of a rotating disk–spindle system in a HDD with hydrodynamic bearings (HDBs) considering the flexibility of a complicated base structure by using finite element method. Finite element equations of each component of a HDD spindle system from the spinning flexible disk to the flexible base plate are consistently derived by satisf...

Windows are a significant path for structure-borne and air-borne noise transmission into aircraft. To improve the acoustical performance, damped windows were fabricated using two or three layers of plexiglas with transparent viscoelastic damping material sandwiched between the layers. In this paper, numerical and experimental results are used to evaluate the acoustic benefits of damped windows....

the natural vibrations of clamped annular isotropic sector plates are analyzed using the extended kantorovich method (ekm). a conformal mapping is used to transform a sector with identified geometry to a rectangular plate which the solution is available in literature and solved by dalaei and kerr [1] using ekm. the developed iterative scheme converges very rapidly to the final result. the obtai...

Modal parameter estimation in terms of natural frequencies and mode shapes is studied using smooth orthogonal decomposition for randomly excited vibration systems. This work shows that under certain conditions, the smooth orthogonal decomposition eigenvalue problem formulated from white noise induced response data can be tied to the unforced structural eigenvalue problem, and thus can be used f...