Forced Vibration of Overhead Transmission Line: Analytical and Experimental Investigation

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
O. Barry ◽  
J. W. Zu ◽  
D. C. D. Oguamanam
Keyword(s):  
Transmission Line ◽  
Damping Ratio ◽  
Excitation Frequency ◽  
Beam Theory ◽  
Overhead Transmission Line ◽  
Proposed Model ◽  
Parametric Studies ◽  
Tip Mass ◽  
Euler Bernoulli Beam ◽  
Stockbridge Damper

An analytical model of a single line transmission line carrying a Stockbridge damper is developed based on the Euler–Bernoulli beam theory. The conductor is modeled as an axially loaded beam and the messenger is represented as a beam with a tip mass at each end. Experiments are conducted to validate the proposed model. An explicit expression is presented for the damping ratio of the conductor. Numerical examples show that the proposed model is more accurate than the models found in the literature. Parametric studies indicate that the response of the conductor significantly depends on the excitation frequency, the location of the damper, and the damper parameters.

Dynamic Stress Analysis of Exposed Pipes Subjected to Moving In-Line Inspection Tool

2020 ◽  
Author(s):  
Hamid Mostaghimi ◽  
Mohsen Hassani ◽  
Deli Yu ◽  
Ron Hugo ◽  
Simon Park
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Stress ◽  
Equations Of Motion ◽  
Excitation Frequency ◽  
Beam Theory ◽  
Assessment Method ◽  
Integrity Assessment ◽  
Defect Assessment ◽  
Proposed Model ◽  
Assessment And Monitoring

Abstract In-line inspection is a non-destructive assessment method commonly used for defect assessment and monitoring of pipelines. The passage of an ILI tool through an excavated or exposed section of a pipe during an integrity assessment can excite vibrations and exert substantial forces, stress, and deflections on the pipe due to the weight and speed of the ILI tool. When the excitation frequency due to the ILI tool movement is close to the natural frequency of the overall structure, the dynamic stress generated within the pipe can be large enough to the extent that it imposes integrity concern on the line. This research aims to study effects of the ILI tool passage through floating and partially supported pipes under a variety of boundary and loading conditions. A finite element method is used to model the pipe with moving ILI tool. The model is developed based on Timoshenko beam theory with planar degrees-of-freedom and the differential equations of motion are solved numerically to predict displacement, strain, stress, and frequency responses of the pipe. The model is further validated using a lab-scale experimental setup. The comparison of the simulation to experimental results show how the proposed model is capable of predicting pipe dynamics, effectively.

scholarly journals Analysis and Implementation of Noncontact Level Sensing for a Pressurized Cylinder

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
Hsien-Huang P. Wu ◽  
Chung-Wen Hung ◽  
Shih-Hsin Chang ◽  
Zong-Hao Yang
Keyword(s):  
Beam Theory ◽  
Bernoulli Beam ◽  
Fluid Level ◽  
Detailed Model ◽  
Gas Cylinder ◽  
Proposed Model ◽  
Empty Condition ◽  
Euler Bernoulli Beam ◽  
Gas Cylinders ◽  
Pressurized Cylinder

Fluid level detection for a sealed and pressurized mobile container is very useful for the provider to schedule the delivery of a new one before it runs out of the liquid. This study suggested using the frequencies of tone generated by knocking on the outside surface of the container to detect the liquid level inside. A detailed model based on Euler-Bernoulli beam theory has been proposed to study the feasibility of this method for a cylinder with complicated but practical structure. Household gas cylinders were used to validate the proposed model and the results show that experimental data agree well with the theoretical analysis. The results indicate that the proposed model can accurately explain the behavior of the vibratory frequencies under different liquid levels. An apparatus has been successfully implemented to automatically sense the near empty condition of the gas cylinder.

Analysis and Characterization of Piezoelectric Energy Harvesting From Galloping and Base Excitations With Complex Electrical Circuitry

2016 ◽  
Author(s):  
Hichem Abdelmoula ◽  
Abdessattar Abdelkefi
Keyword(s):  
Excitation Frequency ◽  
Beam Theory ◽  
Load Resistance ◽  
Electrical Circuit ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
And Performance ◽  
Electrical Components ◽  
Euler Bernoulli Beam ◽  
Quenching Phenomenon

The characteristics and performance of piezoelectric energy harvesters concurrently subjected to galloping and base excitations when using a complex electrical circuit are studied. The considered energy harvester is composed of a bilayered cantilever beam with a square cylindrical structure at its tip. Euler-Bernoulli beam theory, nonlinear quasi-steady hypothesis, and Galerkin method are used to develop a reduced order model of this system. The electrical circuitry of the harvester consists of a load resistance, a capacitance, and an inductance. The impacts of the electrical components of the harvester’s circuitry, the wind speed, and the base excitation frequency and acceleration on the broadband characteristics of the harvester, quenching phenomenon, and appearance of new nonlinear behaviors are deeply investigated and discussed. When both coupled frequencies of electrical and mechanical types exists and are far from each other, it is shown that the quenching phenomenon is only related to the coupled frequency of mechanical type. Unlike the existence of the quenching phenomenon, the results show that the beating phenomenon takes place for different excitation frequencies when they are close to the coupled frequencies of electrical and mechanical types.

Estimation of damping in riveted short cantilever beams

2020 ◽  
Vol 26 (23-24) ◽  
pp. 2163-2173
Author(s):  
Yemineni Siva Sankara Rao ◽  
Kutchibotla Mallikarjuna Rao ◽  
V V Subba Rao
Keyword(s):  
Timoshenko Beam ◽  
Damping Ratio ◽  
Beam Theory ◽  
Timoshenko Beam Theory ◽  
Analytical Models ◽  
Cantilever Beams ◽  
Bernoulli Beam ◽  
Bernoulli Beam Theory ◽  
Half Power ◽  
Euler Bernoulli Beam

In layered and riveted structures, vibration damping happens because of a micro slip that occurs because of a relative motion at the common interfaces of the respective jointed layers. Other parameters that influence the damping mechanism in layered and riveted beams are the amplitude of initial excitation, overall length of the beam, rivet diameter, overall beam thickness, and many layers. In this investigation, using the analytical models such as the Euler–Bernoulli beam theory and Timoshenko beam theory and half-power bandwidth method, the free transverse vibration analysis of layered and riveted short cantilever beams is carried out for observing the damping mechanism by estimating the damping ratio, and the obtained results from the Euler–Bernoulli beam theory and Timoshenko beam theory analytical models are validated by the half-power bandwidth method. Although the Euler–Bernoulli beam model overestimates the damping ratio value by a very less fraction, both the models can be used to evaluate damping for short riveted cantilever beams along with the half-power bandwidth method.

Modeling of V-Shaped Beam-Mass Piezoelectric Energy Harvester: Impact of the Angle Between the Beams

2012 ◽  
Author(s):  
Wei-Jiun Su ◽  
Jean W. Zu
Keyword(s):  
Resonant Frequency ◽  
Energy Harvester ◽  
Beam Theory ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Piezoelectric Layers ◽  
Cantilevered Beam ◽  
Power Frequency ◽  
Tip Mass ◽  
Euler Bernoulli Beam

Piezoelectric material has been widely utilized in vibration-based energy harvesters (VEH). The most common configuration of piezoelectric energy harvester is a cantilevered beam with unimorph or bimorph piezoelectric layers. In this paper, a new configuration of PEH is proposed. Two beams are assembled as V shape with tip masses attached. The first beam is a cantilevered beam with tip mass while the second beam is attached to the end of the first beam with a certain angle. Piezoelectric layers are attached to both beams in unimorph configuration for power generation. The analytical solution is derived based on Euler-Bernoulli beam theory. In this analysis, the angle varies from 0 to 135 degree to see the influence of angle on voltage and power frequency response. The V-shaped VEH is proven to have the second resonant frequency relatively close to the first resonant frequency when compared with conventional cantilevered VEH. Furthermore, the angle between the two beams will influence the ratio of the second to the first resonant frequency. By choosing a suitable angle, the V-shaped structure can effectively broaden the bandwidth.

scholarly journals Rail Joint Model Based on the Euler-Bernoulli Beam Theory

2019 ◽  
Vol 8 (2) ◽  
pp. 16-29
Author(s):  
Traian Mazilu ◽  
Ionuţ Radu Răcănel ◽  
Cristian Lucian Ghindea ◽  
Radu Iuliu Cruciat ◽  
Mihai-Cornel Leu
Keyword(s):  
Beam Theory ◽  
Joint Model ◽  
Experimental Results ◽  
Winkler Foundation ◽  
Bernoulli Beam ◽  
Model Based ◽  
Bernoulli Beam Theory ◽  
Proposed Model ◽  
Joint Gap ◽  
Euler Bernoulli Beam

Abstract In this paper, a rail joint model consisting of three Euler-Bernoulli beams connected via a Winkler foundation is proposed in order to point out the influence of the joint gap length upon the stiffness of the rail joint. Starting from the experimental results aiming the stiffness of the rail joint, the Winkler foundation stiffness of the model has been calculated. Using the proposed model, it is shown that the stiffness of the rail joint of the 49 rail can decreases up to 10 % when the joint gap length increases from 0 to 20 mm.

Dynamic Stress Analysis of Exposed Pipes Subjected to a Moving In-line Inspection Tool

2020 ◽  
pp. 1-35
Author(s):  
Hamid Mostaghimi ◽  
Mohsen Hassani ◽  
Deli Yu ◽  
Ronald J. Hugo ◽  
Simon S. Park
Keyword(s):  
Dynamic Stress ◽  
Excitation Frequency ◽  
Beam Theory ◽  
Element Model ◽  
Assessment Method ◽  
Integrity Assessment ◽  
Defect Assessment ◽  
Pipe Section ◽  
Proposed Model ◽  
Wide Range

Abstract In-line inspection (ILI) is a non-destructive assessment method commonly used for defect assessment and for pipeline monitoring. Passing an ILI tool through an excavated or exposed section of a pipe during an integrity assessment can excite vibrations. The ILI tool's weight and speed can exert substantial forces, stresses, and deflections on the pipe section. When the excitation frequency from the ILI tool's movement is close to the pipe's natural frequency, the dynamic stress generated within the pipe can become great enough that it creates integrity concerns on the pipeline. This research aims to study effects of an ILI tool's passage through exposed and partially supported pipes under a variety of boundary and loading conditions. A finite element model of an exposed pipe section is developed based on the Timoshenko beam theory to predict the pipe's displacement, strain, stress, and frequency responses under a wide range of excitation frequencies. The model is further validated using a lab-scale experimental setup with a mass that moves at different speeds. A comparison between the simulation and the experimental results shows that the proposed model can effectively predict the pipe's dynamics.

Beam-Based Vibration Energy Harvesters Tunable Through Folding

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Anup Pydah ◽  
R. C. Batra
Keyword(s):  
Natural Frequencies ◽  
Excitation Frequency ◽  
Beam Theory ◽  
High Sensitivity ◽  
Vibration Energy ◽  
Vibration Energy Harvester ◽  
Tuning Parameters ◽  
Energy Harvesters ◽  
Single Fold ◽  
Euler Bernoulli Beam

We present a novel beam-based vibration energy harvester, and use a structural tailoring concept to tune its natural frequencies. Using a solution of the Euler–Bernoulli beam theory equations, verified with finite element (FE) solutions of shell theory equations, we show that introducing folds or creases along the span of a slender beam, varying the fold angle at a crease, and changing the crease location helps tune the beam natural frequencies to match an external excitation frequency and maximize the energy harvested. For a beam clamped at both ends, the first frequency can be increased by 175% with a single fold. With two folds, selective frequencies can be tuned, leaving others unchanged. The number of folds, their locations, and the fold angles act as tuning parameters that provide high sensitivity and controllability of the frequency response of the harvester. The analytical model can be used to quickly optimize designs with multiple folds for anticipated external frequencies.

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