his paper studies the sound transmission loss of perforated panels and investigates the efect of the hole diameter on the sound insulation performance under normal incidence of acoustic loading. he hole diameters are distinguished into micro (submillimeter) and macro (millimeter) sizes. In general, the transmission loss reduces as the perforation ratio is increased. However, by retaining the perforation ratio, it is found that the transmission loss increases as the hole diameter is reduced for a perforate with micro holes due to the efect of resistive part in the hole impedance, which is contrary to the results for those with the macro holes. Both show similar trend at high frequency where the luid behavior inside the hole is inertial. Simple analytical formulae for engineering purpose are provided. Validation of the models with measurement data also gives good agreement.
{"title":"Normal Incidence Of Sound Transmission Loss From Perforated Plates With Micro And Macro Size Holes","authors":"A. Putra, A. Y. Ismail","doi":"10.1155/2014/534569","DOIUrl":"https://doi.org/10.1155/2014/534569","url":null,"abstract":"his paper studies the sound transmission loss of perforated panels and investigates the efect of the hole diameter on the \u0000sound insulation performance under normal incidence of acoustic loading. he hole diameters are distinguished into micro \u0000(submillimeter) and macro (millimeter) sizes. In general, the transmission loss reduces as the perforation ratio is increased. \u0000However, by retaining the perforation ratio, it is found that the transmission loss increases as the hole diameter is reduced for \u0000a perforate with micro holes due to the efect of resistive part in the hole impedance, which is contrary to the results for those with \u0000the macro holes. Both show similar trend at high frequency where the luid behavior inside the hole is inertial. Simple analytical \u0000formulae for engineering purpose are provided. Validation of the models with measurement data also gives good agreement.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2014-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/534569","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64538340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amplitude demodulation is a key for diagnosing bearing faults. The quality of the demodulation determines the efficiency of the spectrum analysis in detecting the defect. A signal analysis technique based on minimum entropy deconvolution (MED), empirical mode decomposition (EMD), and Teager Kaiser energy operator (TKEO) is presented. The proposed method consists in enhancing the signal by using MED, decomposing the signal in intrinsic mode functions (IMFs) and selects only the IMF which presents the highest correlation coefficient with the original signal. In this study the first IMF1 was automatically selected, since it represents the contribution of high frequencies which are first excited at the early stages of degradation. After that, TKEO is used to track the modulation energy. The spectrum is applied to the instantaneous amplitude. Therefore, the character of the bearing faults can be recognized according to the envelope spectrum. The simulation and experimental results show that an envelope spectrum analysis based on MED-EMD and TKEO provides a reliable signal analysis tool. The experimental application has been developed on acoustic emission and vibration signals recorded for bearing fault detection.
{"title":"Monitoring Machines by Using a Hybrid Method Combining MED, EMD, and TKEO","authors":"Mourad Kedadouche, M. Thomas, Antoine Tahan","doi":"10.1155/2014/592080","DOIUrl":"https://doi.org/10.1155/2014/592080","url":null,"abstract":"Amplitude demodulation is a key for diagnosing bearing faults. The quality of the demodulation determines the efficiency of the spectrum analysis in detecting the defect. A signal analysis technique based on minimum entropy deconvolution (MED), empirical mode decomposition (EMD), and Teager Kaiser energy operator (TKEO) is presented. The proposed method consists in enhancing the signal by using MED, decomposing the signal in intrinsic mode functions (IMFs) and selects only the IMF which presents the highest correlation coefficient with the original signal. In this study the first IMF1 was automatically selected, since it represents the contribution of high frequencies which are first excited at the early stages of degradation. After that, TKEO is used to track the modulation energy. The spectrum is applied to the instantaneous amplitude. Therefore, the character of the bearing faults can be recognized according to the envelope spectrum. The simulation and experimental results show that an envelope spectrum analysis based on MED-EMD and TKEO provides a reliable signal analysis tool. The experimental application has been developed on acoustic emission and vibration signals recorded for bearing fault detection.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"208-217"},"PeriodicalIF":0.0,"publicationDate":"2014-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/592080","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64563469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamics of a light sphere in a quickly rotating inclined cylinder filled with liquid under transversal vibrations is experimentally investigated. Due to inertial oscillations of the sphere relative to the cavity, its rotation velocity differs from the cavity one. The intensification of the lagging motion of a sphere and the excitation of the outstripping differential rotation are possible under vibrations. It occurs in the resonant areas where the frequency of vibrations coincides with the fundamental frequency of the system. The position of the sphere in the center of the cylinder could be unstable. Different velocities of the sphere are matched with its various quasistationary positions on the axis of rotating cavity. In tilted rotating cylinder, the axial component of the gravity force appears; however, the light sphere does not float to the upper end wall but gets the stable position at a definite distance from it. It makes possible to provide a vibrational suspension of the light sphere in filled with liquid cavity rotating around the vertical axis. It is found that in the wide range of the cavity inclination angles the sphere position is determined by the dimensionless velocity of body differential rotation.
{"title":"Vibrational Suspension of Light Sphere in a Tilted Rotating Cylinder with Liquid","authors":"V. Kozlov, S. Subbotin","doi":"10.1155/2014/608058","DOIUrl":"https://doi.org/10.1155/2014/608058","url":null,"abstract":"The dynamics of a light sphere in a quickly rotating inclined cylinder filled with liquid under transversal vibrations is experimentally investigated. Due to inertial oscillations of the sphere relative to the cavity, its rotation velocity differs from the cavity one. The intensification of the lagging motion of a sphere and the excitation of the outstripping differential rotation are possible under vibrations. It occurs in the resonant areas where the frequency of vibrations coincides with the fundamental frequency of the system. The position of the sphere in the center of the cylinder could be unstable. Different velocities of the sphere are matched with its various quasistationary positions on the axis of rotating cavity. In tilted rotating cylinder, the axial component of the gravity force appears; however, the light sphere does not float to the upper end wall but gets the stable position at a definite distance from it. It makes possible to provide a vibrational suspension of the light sphere in filled with liquid cavity rotating around the vertical axis. It is found that in the wide range of the cavity inclination angles the sphere position is determined by the dimensionless velocity of body differential rotation.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2014-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/608058","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64572918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the regions near to active faults, if the fault rupture propagation is towards the site and the shear wave propagation velocity is near the velocity of fault rupture propagation, the forward directivity effect causes pulse-like long-period large-amplitude vibrations perpendicular to the fault plane which causes a large amount of energy to be imposed to structures in a short time. According to previous investigations, the amounts of input and dissipated energies in the structure represent the general performance of the structure and show the level of damage and flexibility of the structure against earthquake. Therefore, in this study, the distribution of damage in the structure height and its amount at the height of steel moment frames under the pulse-like vibrations in the near fault region has been investigated. The results of this study show that the increase rate of earthquake input energy with respect to increase in the number of stories of the structure in the near field of fault is triple that in the far field of fault which then leads to a 2–2.5 times increase in the earthquake input energy in the high rise moment frames in the near field of fault with respect to that in the far field of fault.
{"title":"Numerical Study on Energy Dissipation of Steel Moment Resisting Frames under Effect of Earthquake Vibrations","authors":"M. Gerami, Davood Abdollahzadeh","doi":"10.1155/2014/510593","DOIUrl":"https://doi.org/10.1155/2014/510593","url":null,"abstract":"In the regions near to active faults, if the fault rupture propagation is towards the site and the shear wave propagation velocity is near the velocity of fault rupture propagation, the forward directivity effect causes pulse-like long-period large-amplitude vibrations perpendicular to the fault plane which causes a large amount of energy to be imposed to structures in a short time. According to previous investigations, the amounts of input and dissipated energies in the structure represent the general performance of the structure and show the level of damage and flexibility of the structure against earthquake. Therefore, in this study, the distribution of damage in the structure height and its amount at the height of steel moment frames under the pulse-like vibrations in the near fault region has been investigated. The results of this study show that the increase rate of earthquake input energy with respect to increase in the number of stories of the structure in the near field of fault is triple that in the far field of fault which then leads to a 2–2.5 times increase in the earthquake input energy in the high rise moment frames in the near field of fault with respect to that in the far field of fault.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2014-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/510593","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64527598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a design method to optimize the material distribution of functionally graded beams with respect to some vibration and acoustic properties. The change of the material distribution through the beam length alters the stiffness and the mass of the beam. This can be used to alter a specific beam natural frequency. It can also be used to reduce the sound power radiated from the vibrating beam. Two novel volume fraction laws are used to describe the material volume distributions through the length of the FGM beam. The proposed method couples the finite element method (for the modal and harmonic analysis), Lumped Parameter Model (for calculating the power of sound radiation), and an optimization technique based on Genetic Algorithm. As a demonstration of this technique, the optimization procedure is applied to maximize the fundamental frequency of FGM cantilever and clamped beams and to minimize the sound radiation from vibrating clamped FGM beam at a specific frequency.
{"title":"Optimization of Natural Frequencies and Sound Power of Beams Using Functionally Graded Material","authors":"Nabeel Alshabatat, K. Naghshineh","doi":"10.1155/2014/752361","DOIUrl":"https://doi.org/10.1155/2014/752361","url":null,"abstract":"This paper presents a design method to optimize the material distribution of functionally graded beams with respect to some vibration and acoustic properties. The change of the material distribution through the beam length alters the stiffness and the mass of the beam. This can be used to alter a specific beam natural frequency. It can also be used to reduce the sound power radiated from the vibrating beam. Two novel volume fraction laws are used to describe the material volume distributions through the length of the FGM beam. The proposed method couples the finite element method (for the modal and harmonic analysis), Lumped Parameter Model (for calculating the power of sound radiation), and an optimization technique based on Genetic Algorithm. As a demonstration of this technique, the optimization procedure is applied to maximize the fundamental frequency of FGM cantilever and clamped beams and to minimize the sound radiation from vibrating clamped FGM beam at a specific frequency.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2014-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/752361","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64656124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The reflection of plane waves at the free surface of thermally conducting micropolar elastic medium with two temperatures is studied. The theory of thermoelasticity with and without energy dissipation is used to investigate the problem. The expressions for amplitudes ratios of reflected waves at different angles of incident wave are obtained. Dissipation of energy and two-temperature effects on these amplitude ratios with angle of incidence are depicted graphically. Some special and particular cases are also deduced.
{"title":"Effect of Two Temperatures on Reflection Coefficient in Micropolar Thermoelastic with and without Energy Dissipation Media","authors":"Rajneesh Kumar, K. Sharma, Shaveta Garg","doi":"10.1155/2014/846721","DOIUrl":"https://doi.org/10.1155/2014/846721","url":null,"abstract":"The reflection of plane waves at the free surface of thermally conducting micropolar elastic medium with two temperatures is studied. The theory of thermoelasticity with and without energy dissipation is used to investigate the problem. The expressions for amplitudes ratios of reflected waves at different angles of incident wave are obtained. Dissipation of energy and two-temperature effects on these amplitude ratios with angle of incidence are depicted graphically. Some special and particular cases are also deduced.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"46 7 1","pages":"247-257"},"PeriodicalIF":0.0,"publicationDate":"2014-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/846721","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64706995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study uses the finite element method (FEM) to analyze the excitation and dead vibration modes of two-dimensional quartz plates. We first simplify three-dimensional quartz plates with plane strain simplification and then compare the modes of the simplified three-dimensional plates to those of two-dimensional plates. We then analyze quartz vibrating elements of AT-cut plates and SC-cut plates. To understand the regularity of the resonance frequency of plates that are excitable by voltage loading, we compare the natural vibrations of quartz plates with the excitation frequency generated after the plates are excited by voltage loading.
{"title":"Analysis of Excitation and Dead Vibration Modes of Quartz Resonators","authors":"Zi-Gui Huang, Zheng-Yu Chen","doi":"10.1155/2014/746847","DOIUrl":"https://doi.org/10.1155/2014/746847","url":null,"abstract":"This study uses the finite element method (FEM) to analyze the excitation and dead vibration modes of two-dimensional quartz plates. We first simplify three-dimensional quartz plates with plane strain simplification and then compare the modes of the simplified three-dimensional plates to those of two-dimensional plates. We then analyze quartz vibrating elements of AT-cut plates and SC-cut plates. To understand the regularity of the resonance frequency of plates that are excitable by voltage loading, we compare the natural vibrations of quartz plates with the excitation frequency generated after the plates are excited by voltage loading.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2014-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/746847","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64651640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Erratum to “Anomalous Dispersion of the S1 Lamb Mode”","authors":"F. Ahmad, T. Hussain","doi":"10.1155/2014/714298","DOIUrl":"https://doi.org/10.1155/2014/714298","url":null,"abstract":"","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2014 1","pages":"267-267"},"PeriodicalIF":0.0,"publicationDate":"2014-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2014/714298","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64632634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes the vibroacoustic coupling between the structural vibrations and internal sound fields of thin structures. In this study, a cylindrical structure with thin end plates is subjected to the harmonic point force at one end plate or both end plates, and a natural frequency of the end plates is selected as the forcing frequency. The resulting vibroacoustic coupling is then analyzed theoretically and experimentally by considering the dynamic behavior of the plates and the acoustic characteristics of the internal sound field as a function of the cylinder length. The length and phase difference between the plate vibrations, which maximize the sound pressure level inside the cavity, are clarified theoretically. The theoretical results are validated experimentally through an excitation experiment using an experimental apparatus that emulates the analytical model. Moreover, the electricity generation experiment verifies that sufficient vibroacoustic coupling can be created for the adopted electricity generating system to be effective as an electric energy-harvesting device.
{"title":"Energy Harvesting with Piezoelectric Element Using Vibroacoustic Coupling Phenomenon","authors":"H. Moriyama, Hirotarou Tsuchiya, Y. Oshinoya","doi":"10.1155/2013/126035","DOIUrl":"https://doi.org/10.1155/2013/126035","url":null,"abstract":"This paper describes the vibroacoustic coupling between the structural vibrations and internal sound fields of thin structures. In this study, a cylindrical structure with thin end plates is subjected to the harmonic point force at one end plate or both end plates, and a natural frequency of the end plates is selected as the forcing frequency. The resulting vibroacoustic coupling is then analyzed theoretically and experimentally by considering the dynamic behavior of the plates and the acoustic characteristics of the internal sound field as a function of the cylinder length. The length and phase difference between the plate vibrations, which maximize the sound pressure level inside the cavity, are clarified theoretically. The theoretical results are validated experimentally through an excitation experiment using an experimental apparatus that emulates the analytical model. Moreover, the electricity generation experiment verifies that sufficient vibroacoustic coupling can be created for the adopted electricity generating system to be effective as an electric energy-harvesting device.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"30 1","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2013-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2013/126035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64375188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Botta, D. Dini, C. Schwingshackl, L. Mare, G. Cerri
Damping of vibrations is often required to improve both the performance and the integrity of engineering structures, for example, gas turbine blades. In this paper, we explore the possibility of using piezoelectric plates to control the multimode vibrations of a cantilever beam. To develop an effective control strategy and optimize the placement of the active piezoelectric elements in terms of vibrations amplitude reduction, a procedure has been developed and a new analytical solution has been proposed. The results obtained have been corroborated by comparison with the results from a multiphysics finite elements package (COMSOL), results available in the literature, and experimental investigations carried out by the authors.
{"title":"Optimal Placement of Piezoelectric Plates to Control Multimode Vibrations of a Beam","authors":"F. Botta, D. Dini, C. Schwingshackl, L. Mare, G. Cerri","doi":"10.1155/2013/905160","DOIUrl":"https://doi.org/10.1155/2013/905160","url":null,"abstract":"Damping of vibrations is often required to improve both the performance and the integrity of engineering structures, for example, gas turbine blades. In this paper, we explore the possibility of using piezoelectric plates to control the multimode vibrations of a cantilever beam. To develop an effective control strategy and optimize the placement of the active piezoelectric elements in terms of vibrations amplitude reduction, a procedure has been developed and a new analytical solution has been proposed. The results obtained have been corroborated by comparison with the results from a multiphysics finite elements package (COMSOL), results available in the literature, and experimental investigations carried out by the authors.","PeriodicalId":44068,"journal":{"name":"Advances in Acoustics and Vibration","volume":"2013 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2013-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2013/905160","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64306978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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