Yiu-Yin Lee

Bio: Yiu-Yin Lee is an academic researcher from City University of Hong Kong. The author has contributed to research in topics: Vibration & Nonlinear system. The author has an hindex of 21, co-authored 92 publications receiving 1727 citations. Previous affiliations of Yiu-Yin Lee include Hong Kong Polytechnic University & Old Dominion University.

Non-linear finite element modal approach for the large amplitude free vibration of symmetric and unsymmetric composite plates

Abstract: A theoretical analysis is presented for the large amplitude vibration of symmetric and unsymmetric composite plates using the non-linear finite element modal reduction method. The problem is first reduced to a set of Duffing-type modal equations using the finite element modal reduction method. The main advantage of the proposed approach is that no updating of the non-linear stiffness matrices is needed. Without loss of generality, accurate frequency ratios for the fundamental mode and the higher modes of a composite plate at various values of maximum deflection are then determined by using the Runge–Kutta numerical integration scheme. The procedure for obtaining proper initial conditions for the periodic plate motions is very time consuming. Thus, an alternative scheme (the harmonic balance method) is adopted and assessed, as it was employed to formulate the large amplitude free vibration of beams in a previous study, and the results agreed well with the elliptic solution. The numerical results that are obtained with the harmonic balance method agree reasonably well with those obtained with the Runge–Kutta method. The contribution of each linear mode to the maximum deflection of a plate can also be obtained. The frequency ratios for isotropic and composite plates at various maximum deflections are presented, and convergence of frequencies with the number of finite elements, number of linear modes, and number of harmonic terms is also studied. Copyright © 2005 John Wiley & Sons, Ltd.

The Control of Structure-Borne Noise from a Viaduct Using Floating Honeycomb Panel

Abstract: This paper identifies the method to control the vibration responses of a concrete viaduct model under impulsive force excitation. The frequencies and mode shapes of resonances of the bending vibration across the section can control the magnitude of the structure-borne noise radiation. A plastic hammer is used to excite the cement viaduct model at the centre and at the supporting edge position of the cross-section separately. The results of analysis using a Finite Element Method are confirmed by the experimental findings of the cross-sectional modes. The findings showed that the local modes are of two types: (1) Centre mode ─ the centre of top panel can move but the edge is fixed. (2) Edge (web) mode ─ the centre of panel is fixed but the edge (supported by web) can move. It is found that by supporting the machines on the edge, the center mode will not be excited but the combined mode of edge and center mode can give rise to significant noise radiation. A honeycomb panel with high resonance frequency is used to reduce the vibration transmission from this combined mode. The design can be used as an alternative to floating slab for reducing noise.

Introduction to the Finite Element Method

Abstract: This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Vibration of nonlocal Timoshenko beams

Abstract: This paper is concerned with the free vibration problem for micro/nanobeams modelled after Eringen's nonlocal elasticity theory and Timoshenko beam theory. The small scale effect is taken into consideration in the former theory while the effects of transverse shear deformation and rotary inertia are accounted for in the latter theory. The governing equations and the boundary conditions are derived using Hamilton's principle. These equations are solved analytically for the vibration frequencies of beams with various end conditions. The vibration solutions obtained provide a better representation of the vibration behaviour of short, stubby, micro/nanobeams where the effects of small scale, transverse shear deformation and rotary inertia are significant. The exact vibration solutions should serve as benchmark results for verifying numerically obtained solutions based on other beam models and solution techniques.

An efficient and simple higher order shear and normal deformation theory for functionally graded material (FGM) plates

Abstract: In this paper, an efficient and simple higher order shear and normal deformation theory is presented for functionally graded material (FGM) plates. By dividing the transverse displacement into bending, shear and thickness stretching parts, the number of unknowns and governing equations for the present theory is reduced, significantly facilitating engineering analysis. Indeed, the number of unknown functions involved in the present theory is only five, as opposed to six or even greater numbers in the case of other shear and normal deformation theories. The present theory accounts for both shear deformation and thickness stretching effects by a hyperbolic variation of all displacements across the thickness, and satisfies the stress-free boundary conditions on the upper and lower surfaces of the plate without requiring any shear correction factor. Equations of motion are derived from Hamilton’s principle. Analytical solutions for the bending and free vibration analysis are obtained for simply supported plates. The obtained results are compared with 3-dimensional and quasi-3-dimensional solutions and those predicted by other plate theories. It can be concluded that the present theory is not only accurate but also simple in predicting the bending and free vibration responses of functionally graded plates.