Modal Analysis of a Spinning Cylindrical Shell with Interior Point or Circular Line Supports

1993 ◽  
Vol 115 (4) ◽  
pp. 535-543 ◽  
Author(s):  
Shyh-Chin Huang ◽  
Bih-Sheng Hsu
Keyword(s):  
Cylindrical Shell ◽  
Modal Analysis ◽  
Physical Interpretation ◽  
Interior Point ◽  
Rotational Speed ◽  
Frequency Equation ◽  
Mode Shapes ◽  
Point Support ◽  
Frequency Changes ◽  
Circular Line

An approach to the modal analysis of a spinning cylindrical shell with interior multipoint or circular-line supports is developed. Receptance theory is applied for joining the shell and supports. The frequency equation and mode shapes are then formulated. Conjugate pairing in cross receptances is found in the point support case, but not in the circular line support case. Numerical results for various numbers of point supports are illustrated, and physical interpretation of those results is given. Effects of rotational speed on frequency changes are also addressed.

Free Vibration of a Circular Cylindrical Shell Elastically Restrained by Axially Spaced Springs

1983 ◽  
Vol 50 (3) ◽  
pp. 544-548 ◽  
Author(s):  
T. Irie ◽  
G. Yamada ◽  
Y. Muramoto
Keyword(s):  
Cylindrical Shell ◽  
Free Vibration ◽  
Circular Cylindrical Shell ◽  
Frequency Equation ◽  
Mode Shapes ◽  
Governing Equations ◽  
Structure Matrix ◽  
The Matrix ◽  
Circular Cylindrical Shells ◽  
Elastically Restrained

An analysis is presented for the free vibration of a circular cylindrical shell restrained by axially spaced elastic springs. The governing equations of vibration of a circular cylindrical shell are written as a coupled set of first-order differential equations by using the transfer matrix of the shell. Once the matrix has been determined, the entire structure matrix is obtained by the product of the transfer matrices and the point matrices at the springs, and the frequency equation is derived with terms of the elements of the structure matrix under the boundary conditions. The method is applied to circular cylindrical shells supported by axially equispaced springs of the same stiffness, and the natural frequencies and the mode shapes of vibration are calculated numerically.

Damage Detection of a Circular Cylindrical Shell with Frequency Sensitivities

2006 ◽  
Vol 306-308 ◽  
pp. 253-258
Author(s):  
Jianyun Chen ◽  
Zhi Hua Wang ◽  
Zai Bin Cheng ◽  
Hong Wei Ma
Keyword(s):  
Cylindrical Shell ◽  
Damage Detection ◽  
Circular Cylindrical Shell ◽  
Order Approximation ◽  
Small Error ◽  
Mode Shapes ◽  
Axial Position ◽  
Detection Scheme ◽  
Damage Extent ◽  
Frequency Changes

Damage detection using changes in global dynamic characteristics has been a hot research topic in recent years. In the present paper, based on natural frequencies and mode shapes, a numerical tudy locating and assessing damage in a circular cylindrical shell is presented. The axial position of the damage can be easily obtained by comparing the theoretical and measured frequency changes due to damage. Additional information of mode shapes is introduced to locate the exact damage position. And the damage extent can be estimated by the first order approximation method. The feasibility and practicality of the damage detection scheme are evaluated for several damage scenarios by locating and sizing damage in free-clamped shells. The results illustrate that the proposed detection scheme can confidently locate the single or multiple positions of damage. It is also observed that damage extent can be estimated with a relatively small error.

scholarly journals Vibration Modes and Parameter Analysis of V-Shaped Electrothermal Microactuators

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Zhuo Zhang ◽  
Yueqing Yu ◽  
Xuping Zhang
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Frequency Equation ◽  
Parameter Analysis ◽  
Mode Shapes ◽  
Element Analysis ◽  
Shaped Beam ◽  
The Finite Element Analysis ◽  
Parametric Studies ◽  
First Time

Comprehensive analysis on the modal characteristics of V-shaped electrothermal microactuators is presented in this paper for the first time. Considering the unique geometric characteristics of the V-shaped beam, that is, two inclined beams supporting a movable shuttle, both the lateral and longitudinal deflections are taken into account in the modal analysis. Boundary and continuity conditions are employed to obtain the frequency equation. Natural frequencies are then obtained by solving the frequency equation. Mode shapes corresponding to their natural frequencies are also calculated analytically. The theoretical modal analysis is verified with the finite element analysis using ANSYS software. Based on the model analysis, this paper further investigates the relationship between natural frequencies and the volume scaling of the V-shaped beam. Finally, comprehensive parametric studies in terms of material properties and structural dimensions are conducted to provide insights and guidance in designing the V-shaped beam electrothermal microactuators.

Theory of Receptance Applied to Modal Analysis of a Spinning Disk With Interior Multi-Point Supports

1992 ◽  
Vol 114 (4) ◽  
pp. 468-476 ◽  
Author(s):  
S. C. Huang ◽  
B. S. Hsu
Keyword(s):  
Modal Analysis ◽  
Vibration Analysis ◽  
Critical Speed ◽  
Rotation Speed ◽  
Frequency Equation ◽  
Numerical Results ◽  
Mode Shapes ◽  
Spinning Disk ◽  
Nodal Pattern ◽  
Receptance Method

The theory of receptance applied to the modal analysis of a spinning disk with interior multi-point supports is developed. Traveling modes are first introduced for the vibration analysis of a spinning disk. The receptance method is then applied to join the spinning disk and the point supports. The frequency equation and mode shapes are then formulated. An important property, conjugate pairing of the cross receptances is derived. This feature has never been described before in the literature. Numerical results for various numbers of point supports are illustrated. The results show that the nodal pattern of a spinning disk with point supports is varying periodically. The change of rotation speed further causes the mode exchange phenomenon. The change of first critical speed due to point supports is also discussed.

Effect of Bass Bar Tension on Modal Parameters of a Violin's Top Plate

2015 ◽  
Vol 39 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Ewa B. Skrodzka ◽  
Bogumił B.J. Linde ◽  
Antoni Krupa
Keyword(s):  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Normal Value ◽  
Modal Damping

Abstract Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1-).

scholarly journals Comparison of Mode Shapes of Carbon-Fiber-Reinforced Plastic Material Considering Carbon Fiber Direction

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 311
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic

Previous studies have demonstrated the sensitivity of the dynamic behavior of carbon-fiber-reinforced plastic (CFRP) material over the carbon fiber direction by performing uniaxial excitation tests on a simple specimen. However, the variations in modal parameters (damping coefficient and resonance frequency) over the direction of carbon fiber have been partially explained in previous studies because all modal parameters have only been calculated using the representative summed frequency response function without modal analysis. In this study, the dynamic behavior of CFRP specimens was identified from experimental modal analysis and compared five CFRP specimens (carbon fiber direction: 0°, 30°, 45°, 60°, and 90°) and an isotropic SCS13A specimen using the modal assurance criterion. The first four modes were derived from the SCS13A specimen; they were used as reference modes after verifying with the analysis results from a finite element model. Most of the four mode shapes were found in all CFRP specimens, and the similarity increased when the carbon fiber direction was more than 45°. The anisotropic nature was dominant in three cases of carbon fiber, from 0° to 45°, and the most sensitive case was found in Specimen #3.

Complex Modal Analysis of Non-Self-Adjoint Hybrid Serpentine Belt Drive Systems

2000 ◽  
Vol 123 (2) ◽  
pp. 150-156 ◽  
Author(s):  
Lixin Zhang ◽  
Jean W. Zu ◽  
Zhichao Hou
Keyword(s):  
Modal Analysis ◽  
Closed Form ◽  
Closed Form Solution ◽  
Form Solution ◽  
Mode Shapes ◽  
Belt Drive ◽  
Serpentine Belt ◽  
Complex Modal Analysis ◽  
Drive Systems ◽  
Complex Modal

A linear damped hybrid (continuous/discrete components) model is developed in this paper to characterize the dynamic behavior of serpentine belt drive systems. Both internal material damping and external tensioner arm damping are considered. The complex modal analysis method is developed to perform dynamic analysis of linear non-self-adjoint hybrid serpentine belt-drive systems. The adjoint eigenfunctions are acquired in terms of the mode shapes of an auxiliary hybrid system. The closed-form characteristic equation of eigenvalues and the exact closed-form solution for dynamic response of the non-self-adjoint hybrid model are obtained. Numerical simulations are performed to demonstrate the method of analysis. It is shown that there exists an optimum damping value for each vibration mode at which vibration decays the fastest.

The Use of Modan 3D in Experimental Modal Analysis

2013 ◽  
Vol 486 ◽  
pp. 36-41 ◽  
Author(s):  
Róbert Huňady ◽  
František Trebuňa ◽  
Martin Hagara ◽  
Martin Schrötter
Keyword(s):  
Modal Analysis ◽  
Vibration Analysis ◽  
High Speed ◽  
Mechanical Vibration ◽  
Steel Sample ◽  
Experimental Modal Analysis ◽  
Image Correlation ◽  
Optical Methods ◽  
Mode Shapes ◽  
Vibration Modes

Experimental modal analysis is a relatively young part of dynamics, which deals with the vibration modes identification of machines or their parts. Its development has started since the beginning of the eighties, when the computers hardware equipment has improved and the fast Fourier transform (FFT) could be used for the results determination. Nowadays it provides an uncountable set of vibration analysis possibilities starting with conventional contact transducers of acceleration and ending with modern noncontact optical methods. In this contribution we mention the use of high-speed digital image correlation by experimental determination of mode shapes and modal frequencies. The aim of our work is to create a program application called Modan 3D enabling the performing of experimental modal analysis and operational modal analysis. In this paper the experimental modal analysis of a thin steel sample performed with Q-450 Dantec Dynamics is described. In Modan 3D the experiment data were processed and the vibration modes were determined. The reached results were verified by PULSE modulus specialized for mechanical vibration analysis.

scholarly journals Modal analysis of an iced offshore composite wind turbine blade

2021 ◽  
pp. 0309524X2110116
Author(s):  
Oumnia Lagdani ◽  
Mostapha Tarfaoui ◽  
Mourad Nachtane ◽  
Mourad Trihi ◽  
Houda Laaouidi
Keyword(s):  
Wind Turbine ◽  
Modal Analysis ◽  
Turbine Blade ◽  
Natural Frequencies ◽  
Wind Turbine Blade ◽  
Resonance Phenomenon ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
Numerical Work ◽  
Composite Blades

In the far north, low temperatures and atmospheric icing are a major danger for the safe operation of wind turbines. It can cause several problems in fatigue loads, the balance of the rotor and aerodynamics. With the aim of improving the rigidity of the wind turbine blade, composite materials are currently being used. A numerical work aims to evaluate the effect of ice on composite blades and to determine the most adequate material under icing conditions. Different ice thicknesses are considered in the lower part of the blade. In this paper, modal analysis is performed to obtain the natural frequencies and corresponding mode shapes of the structure. This analysis is elaborated using the finite element method (FEM) computer program through ABAQUS software. The results have laid that the natural frequencies of the blade varied according to the material and thickness of ice and that there is no resonance phenomenon.

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