Experimental Study on Vibration Modes of a Spherical Vessel

2013 ◽  
Author(s):  
Y. Gu ◽  
Q. Dong
Keyword(s):  
Experimental Study ◽  
Mode Frequency ◽  
The Other ◽  
Dynamic Responses ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Spherical Vessel ◽  
Containment Vessel ◽  
Internal Blast Loading ◽  
Blast Loadings

When containment vessels are subjected to internal blast loading, not only the breathing mode, but also the other vibration modes may be excited. Therefore, it is very important to understand the vibration modes in spherical containment vessels. In this paper, we present experimental results of modal analysis of a spherical containment vessel, in which the mode frequency and mode shapes are given. We also conduct the frequency analysis on dynamic responses of the spherical containment vessel subjected to three different blast loadings, in which the vibration modes excited in the dynamic vibration are found. The current study may provide further understanding on dynamic responses of containment vessels.

scholarly journals Prediction of the Resonant Response of Frictionally Constrained Blade Systems Using Constrained Mode Shapes

1998 ◽  
Author(s):  
J. J. Chen ◽  
C. H. Menq
Keyword(s):  
Contact Point ◽  
Element Model ◽  
The Other ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Cyclic Symmetry ◽  
Resonant Response ◽  
Friction Contact ◽  
Blade System ◽  
Free Mode

In this paper, the concept of constrained mode shapes is employed to predict the resonant response of a frictionally constrained blade system. For a tuned blade system, the constrained mode shapes can be calculated using a finite element model of a single blade along with the cyclic symmetry constraint that simulates a fully stuck friction contact. The resulting constrained mode shapes are often complex and can be used to obtain the constrained receptance of the frictionally constrained blade. It is shown that by examining each mode’s contribution to the receptance at the friction contact point, the importance of each individual modes to the prediction of the resonant response of a frictionally constrained blade can be determined. Furthermore, by comparing the receptances calculated from free mode shapes and those from constrained mode shapes, it is found that in the neighborhood of the fully slipping region, the prediction of resonant response requires fewer number of modes when using free mode shapes compared to using constrained mode shapes. On the other hand, in the neighborhood of the fully stuck region, it requires fewer number of modes if constrained mode shapes are used. Therefore, when high preload at the friction contact is desirable, such as for shrouded blade systems, using the constrained mode shapes for the prediction of resonant response is preferred. Moreover, the concept of hybrid receptance is introduced so as to yield very accurate prediction of the resonant response based on only very few vibration modes.

Seismic Testing and Verification for 30 Tons Scaled-Down Model of Reinforced Concrete Containment Vessel

2013 ◽  
Vol 479-480 ◽  
pp. 1051-1055
Author(s):  
Yu Chih Chen ◽  
Wei Ting Lin ◽  
Tung Liang Chu ◽  
Yuan Chieh Wu
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Numerical Model ◽  
Experimental Test ◽  
Seismic Loading ◽  
Shaking Table ◽  
The Other ◽  
Dynamic Responses ◽  
Testing Model ◽  
Containment Vessel

The scaled-down model of Reinforced Concrete Containment Vessel (RCCV) for Advanced Boiling Water Reactor (ABWR) building, whose weight is 30 tons, is the biggest seismic test in Taiwan, until now. The design and stress analysis of the testing model is following the ASME-359 code. This experimental test can be the basis to check whether the scaled-down RCCV is safe or not when it undergoes the fictitious seismic loading came from shaking table. The other object of this test is getting the experimental data of dynamic responses, such as accelerations and displacements, to verify the validity of numerical model.

A Study of Judder Vibration in Automotive Disk Brakes

2006 ◽  
Vol 326-328 ◽  
pp. 1301-1304 ◽  
Author(s):  
Ho Joon Cho ◽  
Chong Du Cho ◽  
Myoung Gu Kim ◽  
Ju Wong Maeng ◽  
Sang Kyo Lee
Keyword(s):  
Hot Spots ◽  
Hot Spot ◽  
Infrared Camera ◽  
Mode Frequency ◽  
Mode Shapes ◽  
Vibration Modes ◽  
The Finite Element Method ◽  
Brake Disk ◽  
Disk Brake ◽  
The Relationship

In this experimental paper, the judder vibration of automotive disk brake was analyzed by the finite element method and compared with experimental results. The relationship between specific modes of disk and pad, and hot spot was investigated. Characteristics of the judder vibration were measured by using the chassis-dynamo and hot spots were photographed by highspeed infrared camera. Vibration modes of the brake disk and pad were measured and an specific relationship between mode shapes and hot spots was found. Results show that the judder vibration occurred due to the frequency modulation of the specific mode frequency of disk brake due to the non-linearity phenomenon. This relationship was examined by the frequency analysis of the judder vibration.

Application of partial eigenvalue assignment techniques to dampen electromechanical oscillations in multi-machine power systems

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Erick Baleeiro da Silva ◽  
José Mário Araújo
Keyword(s):  
Power Systems ◽  
The Other ◽  
Mode Shapes ◽  
Eigenstructure Assignment ◽  
Power System Stabilizers ◽  
Control Effort ◽  
Electromechanical Oscillations ◽  
Oscillation Modes ◽  
Partial Controllability

AbstractIn this study, a methodology for partial eigenstructure assignment (PEVA) is applied to dampen electromechanical oscillations in electrical multi-machine power systems. The approach is anchored in allocating a small number of undesirable eigenvalues, for example, which are poorly damped, preserving the other eigenvalues in the system - the so-called no-spillover spectrum. The new position of the selected eigenvalues is carried out based on the partial controllability analysis of the system, in order to minimize the control effort. Simulation examples using a system with 68 buses, 16 generators and five areas showed that the presented methodology is efficient in dampening the local and inter-area oscillation modes when compared to the classic power system stabilizers (PSS). The quality of the solution is illustrated through computer simulations, eigenvalues tables and mode-shapes.

Effectiveness of Virtual Resilience Training on Assertiveness in Student Girls Aged 9–10 Years: A 1-Month Follow-Up

2021 ◽  
pp. 105984052110135
Author(s):  
Shima Gadari ◽  
Jamile Farokhzadian ◽  
Parvin Mangolian Shahrbabaki
Keyword(s):  
Experimental Study ◽  
Internal Stress ◽  
Intervention Group ◽  
The Other ◽  
Hormonal Changes ◽  
Emotional Instability ◽  
Other Hand ◽  
Significant Difference ◽  
Resilience Training

Girls between the ages of 9 and 10 begin to experience physical, physiological, and hormonal changes that may lead to internal stress. At this age, children are struggling for autonomy; on the other hand, they may experience emotional instability, and for these reasons, they may be vulnerable in many ways. This experimental study aimed to investigate the effect of resilience training on assertiveness in student girls aged 9–10. Data were collected before, immediately after, and 1 month after the intervention in the control ( n = 40) and intervention ( n = 37) groups. There was a significant difference between the assertiveness of the intervention immediately (26.80 ± 3.73) and 1 month after the intervention (27.05 ± 3.73), and assertiveness significantly increased in the intervention group ( p = .0001). Resilience training leads to improvements in assertiveness in student girls aged 9–10.

Study of wave attenuation in concrete

1993 ◽  
Vol 8 (9) ◽  
pp. 2344-2353 ◽  
Author(s):  
J-M. Berthelot ◽  
Souda M. Ben ◽  
J.L. Robert
Keyword(s):  
Experimental Study ◽  
Plane Wave ◽  
Wave Attenuation ◽  
Plane Waves ◽  
Propagation Distance ◽  
Experimental Results ◽  
The Other ◽  
Wave Frequency ◽  
Concrete Composition ◽  
Analytical Expression

The experimental study of wave attenuation in concrete has been achieved in the case of the propagation of plane waves in concrete rods. Different mortars and concretes have been investigated. A transmitter transducer coupled to one of the ends of the concrete rod generates the propagation of a plane wave in the rod. The receiver transducer, similar to the previous one, is coupled to the other end of the rod. The experimental results lead to an analytical expression for wave attenuation as function of the concrete composition, the propagation distance, and the wave frequency.

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.

Experimental Study on Racetrack-Shaped Holes Impingement Cooling With Bump Type Roughening Element

2012 ◽  
Author(s):  
Chiyuki Nakamata ◽  
Yoji Okita ◽  
Takashi Yamane ◽  
Yoshitaka Fukuyama ◽  
Toyoaki Yoshida
Keyword(s):  
Experimental Study ◽  
Flow Condition ◽  
Reynolds Numbers ◽  
Main Flow ◽  
The Other ◽  
Relative Location ◽  
Target Plate ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Cooling Air

Cooling effectiveness of an impingement cooling with array of racetrack-shaped impingement holes is investigated. Two types of specimens are investigated. One is a plain target plate and the other is a plate roughened with bump type elements. Sensitivity of relative location of bump to impingement hole on the cooling effectiveness is also investigated. Experiments are conducted under three different mainflow Reynolds numbers ranging from 2.6×105 to 4.7×105, with four different cooling air Reynolds numbers for each main flow condition. The cooling air Reynolds numbers are in the range from 1.2×103 to 1.3×104.

Identifying VIV Vibration Modes by Use of the Empirical Orthogonal Functions Technique

2002 ◽  
Author(s):  
Gudmund Kleiven
Keyword(s):  
Model Test ◽  
Vibration Mode ◽  
Multivariate Data ◽  
Empirical Orthogonal Functions ◽  
Mode Shapes ◽  
Data Sets ◽  
Vibration Modes ◽  
Ocean Engineering ◽  
Orthogonal Functions ◽  
Related Technique

The Empirical Orthogonal Functions (EOF) technique has widely being used by oceanographers and meteorologists, while the Singular Value Decomposition (SVD being a related technique is frequently used in the statistics community. Another related technique called Principal Component Analysis (PCA) is observed being used for instance in pattern recognition. The predominant applications of these techniques are data compression of multivariate data sets which also facilitates subsequent statistical analysis of such data sets. Within Ocean Engineering the EOF technique is not yet widely in use, although there are several areas where multivariate data sets occur and where the EOF technique could represent a supplementary analysis technique. Examples are oceanographic data, in particular current data. Furthermore data sets of model- or full-scale data of loads and responses of slender bodies, such as pipelines and risers are relevant examples. One attractive property of the EOF technique is that it does not require any a priori information on the physical system by which the data is generated. In the present paper a description of the EOF technique is given. Thereafter an example on use of the EOF technique is presented. The example is analysis of response data from a model test of a pipeline in a long free span exposed to current. The model test program was carried out in order to identify the occurrence of multi-mode vibrations and vibration mode amplitudes. In the present example the EOF technique demonstrates the capability of identifying predominant vibration modes of inline as well as cross-flow vibrations. Vibration mode shapes together with mode amplitudes and frequencies are also estimated. Although the present example is not sufficient for concluding on the applicability of the EOF technique on a general basis, the results of the present example demonstrate some of the potential of the technique.

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