Free Vibration Frequencies of Lock Gate Structure

2020 ◽  
pp. 135-148
Author(s):  
Deepak Kumar Singh ◽  
Priyaranjan Pal ◽  
Shashi Kant Duggal
Keyword(s):  
Free Vibration ◽  
Vibration Frequencies ◽  
Gate Structure ◽  
Lock Gate

Free Vibration Analysis of Lock Gate Structure

2020 ◽  
Vol 36 (4) ◽  
pp. 507-520
Author(s):  
Deepak Kumar Singh ◽  
Priyaranjan Pal ◽  
S. K. Duggal
Keyword(s):  
Natural Frequencies ◽  
Plate Theory ◽  
Free Vibration Analysis ◽  
Computer Code ◽  
Computational Error ◽  
Surface Conditions ◽  
Cosine Series ◽  
Gate Structure ◽  
Convergence Study ◽  
Lock Gate

ABSTRACTThe effect of fluid on the natural frequencies of a vertical rectangular lock gate is investigated. The fluid is assumed to be inviscid and incompressible having an irrotational flow field. The far boundary of fluid domain is truncated near the lock gate structure by solving the Laplace equation using Fourier half range cosine series expansion. The formulation of lock gate structure is governed using Mindlin’s plate theory. The coupled interaction between the fluid domain and the lock gate structure is established using finite element method (FEM) and a computer code is written using FORTRAN. Convergence study and validation of the formulation are carried out to minimise the computational error. The natural frequencies of lock gate coupled with and without fluid are determined for undisturbed and linearised free surface conditions. By varying extent of fluid domain, the effect on the natural frequencies of lock gate is evaluated. The results of natural frequencies obtained may be useful to the designer when the reservoir lock gate structure is exposed to the natural disasters.

Three alternative versions of the theory for a Timoshenko–Ehrenfest beam on a Winkler–Pasternak foundation

2020 ◽  
pp. 108128652094777
Author(s):  
Giulio Maria Tonzani ◽  
Isaac Elishakoff
Keyword(s):  
Free Vibration ◽  
Boundary Conditions ◽  
Detailed Comparison ◽  
Vibration Frequencies ◽  
Pasternak Foundation ◽  
New Model ◽  
Simply Supported ◽  
Model Based

This paper analyzes the free vibration frequencies of a beam on a Winkler–Pasternak foundation via the original Timoshenko–Ehrenfest theory, a truncated version of the Timoshenko–Ehrenfest equation, and a new model based on slope inertia. We give a detailed comparison between the three models in the context of six different sets of boundary conditions. In particular, we analyze the most common combinations of boundary conditions deriving from three typical end constraints, namely the simply supported end, clamped end, and free end. An interesting intermingling phenomenon is presented for a simply-supported (S-S) beam together with proof of the ‘non-existence’ of zero frequencies for free-free (F-F) and simply supported-free (S-F) beams on a Winkler–Pasternak foundation.

Effect of Centrifugal Force on Frequency Characteristic of Rotating Hollow Cylinders Using a Newly Designed Cylindrical Super Element

2006 ◽  
Author(s):  
M. Bonakdar ◽  
M. T. Ahmadian
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Free Vibration ◽  
Centrifugal Force ◽  
Natural Frequencies ◽  
Rotating Cylinder ◽  
Finite Cylinder ◽  
Vibration Frequencies ◽  
Hollow Cylinders ◽  
Special Case

A sixteen node cylindrical super element is presented for evaluating the free vibration characteristics of a rotating laminated cylinder with conventional boundary conditions. It is shown that the natural frequencies are affected considerably when the centrifugal force is also taken into account. The vibration frequencies of rotating finite cylinder, obtained by conventional finite element are used to evaluate the accuracy of this approach. The special case of a stationary cylinder with zero spinning velocity is also considered as a check on this method. Results indicate only few number of cylindrical super elements are capable of predicting the natural frequency of the rotating cylinder within the same limit as many elements used in the conventional finite element method.

3D Vibration Analysis of Hermetic Capsules by Using Ritz Method

2017 ◽  
Vol 17 (03) ◽  
pp. 1750040
Author(s):  
Jae-Hoon Kang
Keyword(s):  
Eigenvalue Problem ◽  
Free Vibration ◽  
Vibration Analysis ◽  
Legendre Polynomials ◽  
Present Method ◽  
Ritz Method ◽  
Three Dimensional ◽  
Dynamic Equations ◽  
Vibration Frequencies ◽  
Good Agreement

A three-dimensional (3D) method of analysis is presented for determining the free vibration frequencies of a hermetic capsule comprising a cylinder closed with hemi-ellipsoidal caps at both ends. Unlike conventional shell theories, which are mathematically 2D, the present method is based upon the 3D dynamic equations of elasticity. Displacement components [Formula: see text], [Formula: see text], and [Formula: see text] in the radial, circumferential, and axial directions, respectively, are taken to be periodic in [Formula: see text] and in time, and the Legendre polynomials in the r and z directions instead of ordinary ones. Potential (strain) and kinetic energies of the hermetic capsule are formulated, and the Ritz method is used to solve the eigenvalue problem, thereby yielding upper bound values of the frequencies. As the degree of the Legendre polynomials is increased, frequencies converge to the exact values. Typical convergence studies are carried out for the first five frequencies. The frequencies from the present 3D method are in good agreement with those obtained from other 3D approach and 2D shell theories proposed by previous researchers.

Exact Vibration Solution for Exponentially Tapered Cantilever With Tip Mass

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
C.Y. Wang ◽  
C. M. Wang
Keyword(s):  
Numerical Methods ◽  
Free Vibration ◽  
Cantilever Beam ◽  
Technical Note ◽  
Mode Shapes ◽  
Constant Thickness ◽  
Vibration Frequencies ◽  
Tapered Cantilever Beam ◽  
Tip Mass ◽  
First Time

This technical note is concerned with the free vibration problem of a cantilever beam with constant thickness and exponentially decaying width. Existing analytical results for such a vibration beam problem are found to be incomplete because lower frequencies could not be obtained. Presented herein is the exact characteristic equation for generating the complete vibration frequencies for the considered vibrating beam problem. Also the note treated for the first time such a tapered cantilever beam with a tip mass. The exact solutions (frequencies and mode shapes) are important to engineers designing such tapered beams and the results serve as benchmarks for assessing the validity, convergence and accuracy of numerical methods and solutions.

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