Analysis of Pulsations and Vibrations in Fluid-Filled Pipe Systems

1995 ◽  
Author(s):  
Christ A. F. de Jong
Keyword(s):  
Energy Flow ◽  
Vibration Mode ◽  
Pipe Wall ◽  
Acoustic Energy ◽  
Mode Shapes ◽  
Strongly Coupled ◽  
Torsional Waves ◽  
Pipe Systems ◽  
Poisson Contraction ◽  
Excessive Noise

Abstract Pressure pulsations and mechanical vibrations in pipe systems may cause excessive noise and may even lead to damage of piping or machinery. In fluid-filled pipe systems pulsations and vibrations will be strongly coupled. A calculation method has been developed for the simulation of coupled pulsations and vibrations in pipe systems. The analytical method is based upon the transfer matrix method. It describes plane pressure waves in the fluid and extensional, bending and torsional waves in the pipe wall. Fluid pulsations and pipe wall vibrations are coupled at discontinuities (e.g. elbows and T-junctions) and via Poisson contraction of the pipe wall. For a given source description, the model calculates levels of vibration, mode shapes, vibro-acoustic energy flow, etc. The method has been validated experimentally on a test rig consisting of two straight pipes and an elbow. The predicted pulsation and vibration levels agree reasonably well with the measurements.

scholarly journals Impact of Geometrical Imperfections on Estimation of Buckling and Limit Loads in a Silo Segment Using the Vibration Correlation Technique

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 567
Author(s):  
Łukasz Żmuda-Trzebiatowski ◽  
Piotr Iwicki
Keyword(s):  
Natural Frequencies ◽  
Vibration Mode ◽  
Mode Shapes ◽  
Correlation Technique ◽  
Limit Loads ◽  
Linear Buckling ◽  
Geometrical Imperfections ◽  
Linear Problems ◽  
Formed Channel ◽  
Corrugated Wall

The paper examines effectiveness of the vibration correlation technique which allows determining the buckling or limit loads by means of measured natural frequencies of structures. A steel silo segment with a corrugated wall, stiffened with cold-formed channel section columns was analysed. The investigations included numerical analyses of: linear buckling, dynamic eigenvalue and geometrically static non-linear problems. Both perfect and imperfect geometries were considered. Initial geometrical imperfections included first and second buckling and vibration mode shapes with three amplitudes. The vibration correlation technique proved to be useful in estimating limit or buckling loads. It was very efficient in the case of small and medium imperfection magnitudes. The significant deviations between the predicted and calculated buckling and limit loads occurred when large imperfections were considered.

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.

Theoretical and Experimental Investigation of Pipe Wall Thinning Detection Using Guided Waves

2008 ◽  
Author(s):  
Isoharu Nishiguchi ◽  
Fumitoshi Sakata ◽  
Seiichi Hamada
Keyword(s):  
Experimental Data ◽  
Power Generation ◽  
Experimental Investigation ◽  
Reflection Coefficient ◽  
Guided Waves ◽  
Pipe Wall ◽  
Thermal Power ◽  
Wall Thinning ◽  
Torsional Waves ◽  
Simplified Method

A method to investigate pipe wall thinning using guided waves has been developed for pipes in thermal power generation facilities. In this paper, the reflection coefficient and the transmission coefficient are derived for the torsional waves which propagate along a pipe and a simplified method to predict the waveform is proposed. The predictions of the waveforms by the FEM and a simplified method based on the reflection of torsional waves are also examined by comparing with experimental data.

scholarly journals Detection of Material Degradation of a Composite Cylinder Using Mode Shapes and Convolutional Neural Networks

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6686
Author(s):  
Bartosz Miller ◽  
Leonard Ziemiański
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Composite Structures ◽  
Vibration Mode ◽  
Numerical Study ◽  
Mode Shapes ◽  
Zone Size ◽  
Composite Cylinder ◽  
Material Degradation ◽  
Damaged Zone

This paper presents a numerical study of the feasibility of using vibration mode shapes to identify material degradation in composite structures. The considered structure is a multilayer composite cylinder, while the material degradation zone is, for simplicity, considered a square section of the lateral surface of the cylinder. The material degradation zone size and location along the cylinder axis are identified using a deep learning approach (convolutional neural networks, CNNs, are applied) on the basis of previously identified vibration mode shapes. The different numbers and combinations of identified mode shapes used to assess the damaged zone size and location were analyzed in detail. The final selection of mode shapes considered in the identification procedure yielded high accuracy in the identification of the degradation zone.

scholarly journals A System for Acoustic Field Measurement Employing Cartesian Robot

2016 ◽  
Vol 23 (3) ◽  
pp. 333-343 ◽  
Author(s):  
Maciej Szczodrak ◽  
Adam Kurowski ◽  
Józef Kotus ◽  
Andrzej Czyżewski ◽  
Bożena Kostek
Keyword(s):  
Acoustic Field ◽  
Energy Flow ◽  
Velocity Vector ◽  
Sound Pressure ◽  
Sound Field ◽  
Acoustic Energy ◽  
The Other ◽  
Object Shape ◽  
Movement Path ◽  
Optimum Path

AbstractA system setup for measurements of acoustic field, together with the results of 3D visualisations of acoustic energy flow are presented in the paper. Spatial sampling of the field is performed by a Cartesian robot. Automatization of the measurement process is achieved with the use of a specialized control system. The method is based on measuring the sound pressure (scalar) and particle velocity(vector) quantities. The aim of the system is to collect data with a high precision and repeatability. The system is employed for measurements of acoustic energy flow in the proximity of an artificial head in an anechoic chamber. In the measurement setup an algorithm for generation of the probe movement path is included. The algorithm finds the optimum path of the robot movement, taking into account a given 3D object shape present in the measurement space. The results are presented for two cases, first without any obstacle and the other - with an artificial head in the sound field.

Influence of Pipe Geometric Deviations on In-Pipe Machine Locomotion

2014 ◽  
Vol 611 ◽  
pp. 221-226 ◽  
Author(s):  
Tatiana Kelemenová ◽  
František Duchoň ◽  
Michal Puškár ◽  
Michal Kelemen ◽  
Piotr Kuryło ◽  
...  
Keyword(s):  
Production Process ◽  
Pipe Wall ◽  
Main Task ◽  
Direct Influence ◽  
Difference Principle ◽  
Geometric Deviations ◽  
Pipe Systems

The paper deals with the analysis of influence of pipe deviations on in-pipe machine locomotion. In-pipe machine locomotes inside a pipe using the friction difference principle of locomotion. Main task of the machine is inspection of inner pipe wall as the prevention of pipe crack and leaks of transported medium. Pipe systems have deviations of inner pipe wall, which are caused by production process and caused by using of pipe (deformations, sediments, changes from coupling of pipes etc.). These pipe deviations have direct influence on machine locomotion inside the pipe.

Vibration and Noise Reduction Analysis of Snowplow’s GearBox Case Based on Modal Analysis

2016 ◽  
Vol 13 (10) ◽  
pp. 7426-7432
Author(s):  
Xiangyang Jin ◽  
Jun Wang ◽  
. Zhihui ◽  
Zhihui Sun ◽  
Qiyun Yang ◽  
...  
Keyword(s):  
Finite Element ◽  
Noise Reduction ◽  
Modal Analysis ◽  
Vibration Mode ◽  
Element Model ◽  
Element Analysis ◽  
Modeling Technology ◽  
Comparison Results ◽  
Vibration Noise ◽  
Excessive Noise

Study has been conducted on how, where and why does excessive noise generate on the gear-box of the snowplow, and, measures for improvement have been presented. As well, analysis to the generation mechanism of vibration noise of gearbox and gears has been made, to find out the source of the noise. Next, a precise model of the gearbox, built by using 3D modeling technology, was translated into finite element model to make the modal analysis. Through analyzing characteristics of each vibration mode, positions of the gearbox case on which a vibration is most likely to be generated have been determined. To check the accuracy of theoretical calculation, vibration and noise tests were made to the gearbox. Specific measures for improvement were then put forward by combining results from both finite element analysis and experimental analysis. The comparison results showed that: the improved gearbox case had a significant effect on noise reduction, and the goal of reducing vibration and noise was achieved.

Increasing the performance of energy harvesting in vibration mode shapes

2016 ◽  
Vol 1 (2) ◽  
pp. 155-173
Author(s):  
Majid Jabbari ◽  
Mostafa Ghayour ◽  
Hamid Reza Mirdamadi
Keyword(s):  
Energy Harvesting ◽  
Vibration Mode ◽  
Mode Shapes
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