The differential quadrature method is a numerical solution technique for initial and/or boundary problems. It was developed by the late Richard Bellman and his associates in the early 70s and, since then, the technique has been successfully employed in a variety of problems in engineering and physical sciences. The method has been projected by its proponents as a potential alternative to the conventional numerical solution techniques such as the finite difference and finite element methods. This paper presents a state-of-the-art review of the differential quadrature method, which should be of general interest to the computational mechanics community.

Differential Quadrature Method in Computational Mechanics: A Review

Plates are integral parts of most engineering structures and their vibration analysis is required for safe design. Vibration of Plates provides a comprehensive, self-contained introduction to vibration theory and analysis of two-dimensional plates. Reflecting the author's more than 15 years of original research on plate vibration, this book presents new methodologies and demonstrates their effectiveness by providing comprehensive results. The text also offers background information on vibration problems along with a discussion of various plate geometries and boundary conditions, including the new concepts of Boundary Characteristic Orthogonal Polynomials (BCOPs).

Vibration of Plates

Free vibrations of beams with general boundary conditions

The eigenvalue problem for the Laplace operator in two dimensions is classical in mathematics and physics. Nevertheless, computational methods for estimating the eigenvalues are still of much current interest, particularly in applications to acoustic and electromagnetic waveguides. Although our primary interest is with the computational methods, there are a number of theoretical results on the behavior of the eigenvalues and eigenfunctions that are useful for understanding the methods and, in addition, are of interest in themselves. These results are discussed first and then the various computational methods that have been used to estimate the eigenvalues are reviewed with particular emphasis on methods that give error bounds. Some of the more powerful techniques available are illustrated by applying them to a model problem.

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Eigenvalues of the Laplacian in Two Dimensions

The free and forced vibration of a laminated functionally graded beam of variable thickness under thermally induced initial stresses is studied in this paper within the framework of Timoshenko beam theory. The beam consists of a homogeneous substrate and two inhomogeneous functionally graded layers whose material composition follows a power law distribution in the thickness direction in terms of the volume fractions of the material constituents. Both the axial and rotary inertia of the beam are considered in the present analysis. It is assumed that the beam may be clamped, hinged, or free at its ends and is subjected to one-dimensional steady heat conduction in the thickness direction before undergoing dynamic deformation. To include the effect of temperature change, the initial stress state is determined through a thermo-elastic analysis before the free and forced vibration analyses. The differential quadrature method that makes use of Lagrange interpolation polynomials is employed as a numerical solution tool to solve both the thermo-elastic equilibrium equation and dynamic equation. Numerical results are presented in both tabular and graphical forms for various laminated functionally graded beams, showing that vibration frequencies, mode shapes and dynamic response are significantly influenced by the thickness variation, temperature change, slenderness ratio, volume fraction index, the thickness of the functionally graded layer, and the end support conditions.

Free and forced vibration of a laminated FGM Timoshenko beam of variable thickness under heat conduction

The method of differential quadrature and its application to the approximate solution of ocean engineering problems

N ATURAL frequencies of a trapezoidal cantilever plate of variable thickness, which model an aircraft wing structure approximately, are determined using energy techniques. Characteristic orthogonal polynomials in two variables are constructed to describe the structural deflections, which are used in the Rayleigh-Ritz method to obtain the natural frequencies. The fundamental natural frequencies for different parameter values are also obtained using a deflection function containing an optimized exponent. The first technique can be used to obtain the natural frequencies and corresponding mode shapes for the preliminary design of aircraft wing structures.

Transverse Vibrations of a Trapezoidal Cantilever Plate of Variable Thickness

Fundamental frequency of vibration of a Timoshenko beam of non-uniform thickness

Transverse vibrations of thin, elastic plates with concentrated masses and internal elastic supports

An exact analytical solution for unsteady thermal stresses in an infinitely long solid composite cylinder is presented. The unsteady temperature field is determined following Ozisik's (1980) treatment, but a more general solution is achieved by the present approach by considering a heat convection situation at the outer boundary. The plane stress and plane strain states are considered next, and the thermal stresses are evaluated. Results are provided as dimensionless plots for several combinations of thermal and mechanical parameters of practical interest. 6 references.

R.H. Gutierrez

Papers

The method of differential quadrature and its application to the approximate solution of ocean engineering problems

Transverse Vibrations of a Trapezoidal Cantilever Plate of Variable Thickness

Fundamental frequency of vibration of a Timoshenko beam of non-uniform thickness

Transverse vibrations of thin, elastic plates with concentrated masses and internal elastic supports

Analytical solution for unsteady thermal stresses in an infinite cylinder composed of two materials