The Frequencies and Damping of a Cantilever Composite Plate With a Viscoelastic Layer

Author(s):  
P. Cupiał ◽  
J. Nizioł

Abstract In the paper the natural frequencies and modal loss factors of a three-layered rectangular cantilever plate with high-modulus composite face layers and a viscoelastic mid-layer are discussed. Two analysis approaches are considered, the Ritz method and the finite element method. The Ritz analysis is based on an appropriate 2-D plate model. Algebraic polynomials are used which satisfy the necessary geometric boundary conditions. The discretized eigenvalue problem is then solved for complex eigenvalues, from which damped frequencies and modal loss factors are extracted. Both frequencies and loss factors are shown to converge with an increasing number of the polynomials used. Apart from the Ritz method, frequencies and modal loss factors are calculated by the finite element method based on the so-called strain energy method. Comparison between the two approaches is then given.

Author(s):  
Shiro Kobayashi ◽  
Soo-Ik Oh ◽  
Taylan Altan

The concept of the finite-element procedure may be dated back to 1943 when Courant approximated the warping function linearly in each of an assemblage of triangular elements to the St. Venant torsion problem and proceeded to formulate the problem using the principle of minimum potential energy. Similar ideas were used later by several investigators to obtain the approximate solutions to certain boundary-value problems. It was Clough who first introduced the term “finite elements” in the study of plane elasticity problems. The equivalence of this method with the well-known Ritz method was established at a later date, which made it possible to extend the applications to a broad spectrum of problems for which a variational formulation is possible. Since then numerous studies have been reported on the theory and applications of the finite-element method. In this and next chapters the finite-element formulations necessary for the deformation analysis of metal-forming processes are presented. For hot forming processes, heat transfer analysis should also be carried out as well as deformation analysis. Discretization for temperature calculations and coupling of heat transfer and deformation are discussed in Chap. 12. More detailed descriptions of the method in general and the solution techniques can be found in References [3-5], in addition to the books on the finite-element method listed in Chap. 1. The path to the solution of a problem formulated in finite-element form is described in Chap. 1 (Section 1.2). Discretization of a problem consists of the following steps: (1) describing the element, (2) setting up the element equation, and (3) assembling the element equations. Numerical analysis techniques are then applied for obtaining the solution of the global equations. The basis of the element equations and the assembling into global equations is derived in Chap. 5. The solution satisfying eq. (5.20) is obtained from the admissible velocity fields that are constructed by introducing the shape function in such a way that a continuous velocity field over each element can be denned uniquely in terms of velocities of associated nodal points.


Geophysics ◽  
1973 ◽  
Vol 38 (4) ◽  
pp. 737-761 ◽  
Author(s):  
J. H. Coggon

The responses of dipole‐dipole, pole‐dipole, and gradient arrays to a set of ten structures have been computed using the finite element method. Comparison of the responses indicates that: (1) The dipole‐dipole array usually gives the largest anomalies, but the anomalies rarely give information on dip of a structure and are strongly influenced by overburden irregularities. This array gives best overall resolution. (2) Pole‐dipole anomalies are almost as large as dipole‐dipole ones and have the same general form but show less resolution. The lower resolution and the asymmetry of this array make results more difficult to interpret. (3) The gradient array provides dip information and good horizontal resolution. Responses to thin vertical structures are weak, anomalies are strongly affected by overburden irregularities, and there is no effective depth discrimination.


2008 ◽  
Vol 08 (04) ◽  
pp. 531-546 ◽  
Author(s):  
K. RAM KUMAR ◽  
N. GANESAN

In this paper, the vibration and damping of a hollow sandwich box column containing a viscoelastic layer (VEL) or an electrorheological (ER) or magnetorheological (MR) fluid core with a constraining layer are analyzed and a comparison of performance is made. The hollow sandwich box column comprises two skin plates and a VEL/ER/MR fluid core layer. The finite element method is used to study the vibration and damping behaviors of the column. The natural frequencies and modal loss factors are obtained by solving the complex eigenvalue problem. The modal dampings and natural frequencies of the column are calculated for various electric as well as magnetic fields and their performance is compared with that of the viscoelastic core layer for the clamped-free boundary condition. Effects of core thickness, electric voltage and magnetic field on the vibration behavior of the sandwich box column are investigated.


Author(s):  
Kenneth Carroll ◽  
Ernesto Gutierrez-Miravete

When a simply supported composite plate is subjected to a lateral load, the presence of the twist coupling stiffnesses in the governing differential equations of equilibrium does not allow the determination of an exact solution for the deflection and numerical methods must be used. This paper describes a comparison of computed approximations to the deflection of composite laminates subjected to transverse loading obtained using the Ritz method and the finite element method. The Ritz method is implemented with the symbolic manipulation program Maple and ANSYS is used to perform the finite element calculations. Reliable results are obtained using both methods.


Sign in / Sign up

Export Citation Format

Share Document