Vibration Of Rectangular Mindlin Plates Research Articles

An Extended Separation-of-Variable Method for Free Vibration of Rectangular Mindlin Plates

For rectangular thick plates with non-Levy boundary conditions, it is important to explore analytical free vibration solutions because the classical inverse and semi-inverse exact solution methods are not applicable to this category of problems. This work is to develop an extended separation-of-variable (SOV) method to find closed-form analytical solutions for the free vibration of rectangular Mindlin plates with arbitrary homogeneous boundary conditions. In the extended SOV method, characteristic differential equations and boundary conditions in two directions are obtained by employing the Rayleigh principle and the assumption that the mode functions are in the SOV form, and two transcendental eigenvalue equations are achieved through boundary conditions. But these two eigenvalue equations cannot be solved simultaneously since there are two equations and only the natural frequency is the unknown variable. Considering this, the second assumption in this method is that the natural frequencies corresponding to two-direction mode functions are independent of each other in the mathematical sense, thus there are two unknowns in two transcendental eigenvalue equations, and the closed-form solutions for plates with arbitrary boundary conditions can be obtained non-iteratively. From the physical sense, the natural frequencies pertaining to different direction mode functions should be the same, and this conclusion is validated analytically and numerically. The present natural frequencies and mode shapes agree well with those obtained by other analytical and numerical methods. Especially, for the plates with at least two opposite sides simply supported, the present solutions are exact.

Three-Layer Stergen'S Vibration-Free Equation Solution

Short-term dynamic loads in shipbuilding, aircraft building and other areas of science are often caused by explosions and impacts. In general, explosion and shocking effects are caused by heavy objects falling and explosion waves. The effect of these impacts on the construction is generally due to the interaction of the design with explosion waves, falling or striking objects, and so on. Along with the foregoing, it should be noted that the problem of the oscillation of the three-layered sterile dispersion over the length of the load is often solved only in the case of classical equations and this is often the case when has led to errors. Therefore, Grigollyuk-Chulkov equation is used in this article (Harper, n.d.; Wojciechowska, 2006). Y. Xing and B. Liu, “Characteristic equations and closed-form solution for free vibrations of rectangular Mindlin plates, ” Y. Xing and B. Liu, “Closed form solutions for free vibrations of rectangular Mindlin plates, ” and other scholars all over there world were stated about the issue on their investigations and analysis.

Pseudospectral analysis of buckling and free vibration of rectangular Mindlin plates

A study of buckling and free vibration of rectangular Mindlin plates is presented. The analysis is based on the pseudospectral method, which uses basis functions that satisfy the boundary conditions. The equations of motion are collocated to yield a set of algebraic equations that are solved for the critical buckling load and for the natural frequencies in the presence of the in-plane loads. Numerical examples of rectangular plates with SS-C-SS-C boundary conditions are provided for various aspect ratios and thickness ratios, which show good agreement with those of the classical plate theory when the thickness ratio is very small.

Closed form solutions for free vibrations of rectangular Mindlin plates

A new two-eigenfunctions theory, using the amplitude deflection and the generalized curvature as two fundamental eigenfunctions, is proposed for the free vibration solutions of a rectangular Mindlin plate. The three classical eigenvalue differential equations of a Mindlin plate are reformulated to arrive at two new eigenvalue differential equations for the proposed theory. The closed form eigensolutions, which are solved from the two differential equations by means of the method of separation of variables are identical with those via Kirchhoff plate theory for thin plate, and can be employed to predict frequencies for any combinations of simply supported and clamped edge conditions. The free edges can also be dealt with if the other pair of opposite edges are simply supported. Some of the solutions were not available before. The frequency parameters agree closely with the available ones through pb-2 Rayleigh–Ritz method for different aspect ratios and relative thickness of plate.

Characteristic equations and closed-form solutions for free vibrations of rectangular mindlin plates

The direct separation of variables is used to obtain the closed-form solutions for the free vibrations of rectangular Mindlin plates. Three different characteristic equations are derived by using three different methods. It is found that the deflection can be expressed by means of the four characteristic roots and the two rotations should be expressed by all the six characteristic roots, which is the particularity of Mindlin plate theory. And the closed-form solutions, which satisfy two of the three governing equations and all boundary conditions and are accurate for rectangular plates with moderate thickness, are derived for any combinations of simply supported and clamped edges. The free edges can also be dealt with if the other pair of opposite edges is simply supported. The present results agree well with results published previously by other methods for different aspect ratios and relative thickness.

Vibration of rectangular Mindlin plates resting on non-homogenous elastic foundations

This paper is concerned with the vibration behaviour of rectangular Mindlin plates resting on non-homogenous elastic foundations. A rectangular plate is assumed to rest on a non-homogenous elastic foundation that consists of multi-segment Winkler-type elastic foundations. Two parallel edges of the plate are assumed to be simply supported and the two remaining edges may have any combinations of free, simply supported or clamped conditions. The plate is first divided into subdomains along the interfaces of the multi-segment foundations. The Levy solution approach associated with the state space technique is employed to derive the analytical solutions for each subdomain. The domain decomposition method is used to cater for the continuity and equilibrium conditions at the interfaces of the subdomains. First-known exact solutions for vibration of rectangular Mindlin plates on a non-homogenous elastic foundation are obtained. The vibration of square Mindlin plates partially resting on an elastic foundation is studied in detail. The influence of the foundation stiffness parameter, the foundation length ratio and the plate thickness ratio on the frequency parameters of square Mindlin plates is discussed. The exact vibration solutions presented in this paper may be used as benchmarks for researchers to check their numerical methods for such a plate vibration problem. The results are also important for engineers to design plates supported by multi-segment elastic foundations.

Eigenvalue analysis of rectangular mindlin plates by chebyshev pseudospectral method

A study of free vibration of rectangular Mindlin plates is presented. The analysis is based on the Chebyshev pseudospectral method, which uses test functions that satisfy the boundary conditions as basis functions. The result shows that rapid convergence and accuracy as well as the conceptual simplicity are achieved when the pseudospectral method is applied to the solution of eigenvalue problems. Numerical examples of rectangular Mindlin plates with clamped and simply supported boundary conditions are provided for various aspect ratios and thickness-to-length ratios.

Vibration of tapered Mindlin plates in terms of static Timoshenko beam functions

In this paper, the free vibrations of rectangular Mindlin plates with variable thickness in one or two directions are investigated. The thickness variation of the plate is continuous and can be represented by a power function of the rectangular co-ordinates. A wide range of tapered rectangular plates can be described by giving various index values to the power function. Two sets of new admissible functions are developed, respectively, to approximate the flexural displacement and the angle of rotation due to bending of the plate. The eigenfrequency equation is obtained by using the Rayleigh–Ritz method. The complete solutions of displacement and angle of rotation due to bending for a tapered Timoshenko beam (a strip taken from the tapered Mindlin plate in some direction) under a Taylor series of static load have been derived, which are used as the admissible functions of the rectangular Mindlin plates with taper thickness in one or two directions. Unlike conventional admissible functions which are independent of the thickness variation of the plate, the static Timoshenko beam functions presented in this paper are closely connected with the thickness variation of the plate so that higher accuracy and more rapid convergence can be expected. Some numerical results are furnished for both truncated Mindlin plates and sharp-ended Mindlin plates. On the basis of convergence study and comparison with available results in literature, it is shown that the first few eigenfrequencies can be obtained with quite satisfactory accuracy by using only a small number of terms of the static Timoshenko beam functions.

Exact Solutions for Vibration of Multi-Span Rectangular Mindlin Plates

This paper presents the first-known exact solutions for the vibration of multi-span rectangular Mindlin plates with two opposite edges simply supported. The Levy type solution method and the state-space technique are employed to develop an analytical approach to deal with the vibration of rectangular Mindlin plates of multiple spans. Exact vibration frequencies are obtained for two-span square Mindlin plates with varying span ratios and two-, three- and four-equal-span rectangular Mindlin plates. The influence of the span ratios, the number of spans and plate boundary conditions on the vibration behavior of square and rectangular Mindlin plates is examined. The presented exact vibration results may serve as benchmark solutions for such plates.

Differentia Quadrature法を用いた長方形mindlin板の振動解析

Differentia Quadrature法を用いた長方形mindlin板の振動解析

VIBRATION ANALYSIS OF RECTANGULAR MINDLIN PLATES RESTING ON ELASTIC EDGE SUPPORTS

For the first time to the authors' knowledge, the problem of free vibration of a moderately thick rectangular plate with edges elastically restrained against transverse and rotational displacements is considered. The Ritz method combined with a variational formulation and Mindlin plate theory is used. The admissible functions consist of polynomials and basic functions that impose the required boundary conditions on the Mindlin plate. The applicability of the formulation is illustrated using three examples of plates with different combinations of elastically restrained edges and classical boundary conditions. Numerical results are obtained to investigate the effects of elastic spring stiffness, relative thickness and aspect ratio upon the natural frequencies of flexural vibration of rectangular Mindlin plates.

Vibration of Rectangular Mindlin Plates with Intermediate Stiffeners

A first known investigation into the vibratory characteristics of rectangular Mindlin plates with intermediate stiffeners is presented. The Rayleigh-Ritz method is used, with displacement and rotational functions assumed in the form of mathematically complete algebraic polynomials. Sets of numerical frequency parameters for rectangular plates of various boundary conditions, thicknesses and plate dimensions are presented. In the study, the effects of shear deformation and rotary inertia on the vibrational response of the plate structures are investigated. The influence of torsional rigidity and geometric properties of stiffeners on the natural frequency parameters are included. To validate the proposed formulation, numerical results for some simplified problems have been determined where existing literature for these problems can be found. Finally sets of new vibration frequencies for plates with one or more stiffeners in various directions are presented.

Vibration of Rectangular Mindlin Plates by the Spline Strip Method

This paper presents an analysis of the vibrations of rectangular Mindlin plates by the spline strip method. To demonstrate the convergence and accuracy of the method, several examples are solved, and results are compared with those obtained by analytical and other numerical methods. Stable convergence and excellent accuracy are obtained by using high order spline strip models. Frequencies of rectangular thick plates with several boundary conditions have been obtained and the results are presented in tabular form.

Vibration of rectangular mindlin plates with tapered thickness by the spline strip method

This paper presents the vibrations of rectangular Mindlin plates with linearly tapered thicknesses in one direction using the spline strip method. The two opposite edges perpendicular to the direction of the thickness variation are simply supported and the other two edges may be arbitrary boundary conditions. To demonstrate the convergence and accuracy of the present method, several examples are solved, and results are compared with those obtained by the analytical method and by other numerical methods. Stable convergence and excellent accuracy are obtained using the higher order spline strip modes. Accurate frequencies of rectangular thick plates with some boundary conditions are analysed by changing aspect ratios, a b , thickness ratios, b h 0 , tapered ratios, δ. These are presented in tabular form.

Vibration analysis of rectangular mindlin plates by the finite strip method

A finite strip analysis of the vibration of rectangular Mindlin plates with general boundary conditions is described. The normal modes of vibration of Timoshenko beams are used to represent the spatial variation along a strip of the deflection and the two cross-sectional rotations. For the crosswise representation equal-order polynomial interpolation is employed for each of these three basic quantities. The accuracy of the approach is demonstrated by the results of a number of applications to square plates with combinations of simply supported, clamped and free edges.