Pub Date : 2020-06-30DOI: 10.20855/ijav.2020.25.21575
A. I. Anya, Aftab Khan
This article is concerned with the investigation of reflection of waves at the free surface of a rotating micropolar fibre-reinforced thermoelastic medium, in the presence of a magnetic field using Green and Lindsay theory. It is observed that when a P-wave is incident on the free surface of rotating micropolar fibre-reinforced thermoelastic medium in the presence of a magnetic field, four waves are reflected; quasi-longitudinal displacement (qLD), quasi-transverse displacement (qTD), quasi-transverse micro-rotational (qTM) and quasi-thermal waves. The normal modes method, also called the harmonic solution approach, is used simultaneously with Snell’s laws and Maxwell’s equation, governing electromagnetic fields, in the determination of a solution for the micropolar fibrereinforced modelled problem. Amplitude ratios or reflection coefficients, which correspond to reflected waves in vertical and horizontal components, are presented analytically. Moreover, the reflection coefficients are presented using numerically simulated results in graphical form for a particular chosen material. We observe that the micropolar fibre-reinforced, rotation, and magneto-thermoelastic field parameters, have varied degree of effects on the propagation and reflection of waves in the medium. The study should be helpful in understanding the behaviour of propagation and reflection of rotating micropolar fibre-reinforced magneto-thermoelastic machination fields and on future works about behaviour of seismic waves.
{"title":"Reflection and Propagation of Magneto-Thermoelastic Plane Waves at Free Surfaces of a Rotating Micropolar Fibre-Reinforced Medium under G-L Theory","authors":"A. I. Anya, Aftab Khan","doi":"10.20855/ijav.2020.25.21575","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.21575","url":null,"abstract":"This article is concerned with the investigation of reflection of waves at the free surface of a rotating micropolar fibre-reinforced thermoelastic medium, in the presence of a magnetic field using Green and Lindsay theory. It is observed that when a P-wave is incident on the free surface of rotating micropolar fibre-reinforced thermoelastic medium in the presence of a magnetic field, four waves are reflected; quasi-longitudinal displacement (qLD), quasi-transverse displacement (qTD), quasi-transverse micro-rotational (qTM) and quasi-thermal waves. The normal modes method, also called the harmonic solution approach, is used simultaneously with Snell’s laws and Maxwell’s equation, governing electromagnetic fields, in the determination of a solution for the micropolar fibrereinforced modelled problem. Amplitude ratios or reflection coefficients, which correspond to reflected waves in vertical and horizontal components, are presented analytically. Moreover, the reflection coefficients are presented using numerically simulated results in graphical form for a particular chosen material. We observe that the micropolar fibre-reinforced, rotation, and magneto-thermoelastic field parameters, have varied degree of effects on the propagation and reflection of waves in the medium. The study should be helpful in understanding the behaviour of propagation and reflection of rotating micropolar fibre-reinforced magneto-thermoelastic machination fields and on future works about behaviour of seismic waves.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"190-199"},"PeriodicalIF":1.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47706851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-30DOI: 10.20855/ijav.2020.25.21544
G. Nie, Kaike Zhang, Jinxi Liu
Love-type wave propagation has been studied in a layered structure consisting of a thin layer of PMN-PT single crystal deposited on an elastic half-space. The weakly periodic undulations of the upper surface of the layered system and the common interface between the PMN-PT layer and the elastic substrate are considered. The PMNPT single crystal is poled along the [011]c direction so that the macroscopic symmetry is orthonormal mm2. The dispersion relations for electrically open and shorted circuits are obtained. The effects of various parameters including corrugation, undulatory, position and electrical boundary conditions on dispersion properties of Lovetype waves are discussed. The results show that corrugations of the surface and the interface play a dominant role in the propagation of a Love-type wave, especially, the interfacial corrugation can produce an anomalous dispersion in the case of an electrically shorted condition. The surface corrugation enhances the phase velocity of a Love-type wave while the interface corrugation reduces the phase velocity in the range of relatively smaller wavenumber, and these variations gradually tend to vanish with increase in wavenumber. The undulatory parameter and the position parameter present a secondary impact on the dispersion behaviors of a Love-type wave compared with the corrugation parameters, both of them slightly enhance the phase velocity. The obtained results can offer some fundamentals for improving the efficiency and sensitivity of the interface response in the design and application of piezoelectric SAW devices.
{"title":"Love-Type Wave in PMN-PT Single Crystal Layered Structures with Periodic Undulations","authors":"G. Nie, Kaike Zhang, Jinxi Liu","doi":"10.20855/ijav.2020.25.21544","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.21544","url":null,"abstract":"Love-type wave propagation has been studied in a layered structure consisting of a thin layer of PMN-PT single crystal deposited on an elastic half-space. The weakly periodic undulations of the upper surface of the layered system and the common interface between the PMN-PT layer and the elastic substrate are considered. The PMNPT single crystal is poled along the [011]c direction so that the macroscopic symmetry is orthonormal mm2. The dispersion relations for electrically open and shorted circuits are obtained. The effects of various parameters including corrugation, undulatory, position and electrical boundary conditions on dispersion properties of Lovetype waves are discussed. The results show that corrugations of the surface and the interface play a dominant role in the propagation of a Love-type wave, especially, the interfacial corrugation can produce an anomalous dispersion in the case of an electrically shorted condition. The surface corrugation enhances the phase velocity of a Love-type wave while the interface corrugation reduces the phase velocity in the range of relatively smaller wavenumber, and these variations gradually tend to vanish with increase in wavenumber. The undulatory parameter and the position parameter present a secondary impact on the dispersion behaviors of a Love-type wave compared with the corrugation parameters, both of them slightly enhance the phase velocity. The obtained results can offer some fundamentals for improving the efficiency and sensitivity of the interface response in the design and application of piezoelectric SAW devices.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"173-182"},"PeriodicalIF":1.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43227769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-30DOI: 10.20855/ijav.2020.25.11514
Li Zhanlong, Sun Dagang, Qin Yuan, Z. Wenjun, Sun Bao
The electronic control box (ECB) is a key and precise component of a roadheader. The vibration of the ECB is an increasingly prominent issue as the machine capacity grows. In order to promote the isolation effect of the ECB, a whole-body vibration model considering the cutting effect is derived, based upon which the stiffnessdamping matching strategy for the ECB isolator is acquired. For engineering application, the tubular constrained damping isolator (TCDI) is developed based on the constrained damping theory and the matching strategy. The theoretical results show that the isolation effect of the ECB isolator strengthens as the stiffness coefficients decline and the damping coefficients increase. The configurations with larger rear stiffness coefficients and larger front damping coefficients could lead to a better vibration control effect. The experiment results indicate that the TCDI exhibits a greater capability of isolating the impact excitation than the traditional E-type isolator, thus verifying the whole-body vibration model for the roadheader and the matching strategy for the ECB isolator. This research can provide theoretical and practical references for the investigation of the dynamic behaviour of complex viscoelastic structures.
{"title":"Stiffness-Damping Matching Modelling for Vibration Isolation System of Roadheader ECB","authors":"Li Zhanlong, Sun Dagang, Qin Yuan, Z. Wenjun, Sun Bao","doi":"10.20855/ijav.2020.25.11514","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.11514","url":null,"abstract":"The electronic control box (ECB) is a key and precise component of a roadheader. The vibration of the ECB is an increasingly prominent issue as the machine capacity grows. In order to promote the isolation effect of the ECB, a whole-body vibration model considering the cutting effect is derived, based upon which the stiffnessdamping matching strategy for the ECB isolator is acquired. For engineering application, the tubular constrained damping isolator (TCDI) is developed based on the constrained damping theory and the matching strategy. The theoretical results show that the isolation effect of the ECB isolator strengthens as the stiffness coefficients decline and the damping coefficients increase. The configurations with larger rear stiffness coefficients and larger front damping coefficients could lead to a better vibration control effect. The experiment results indicate that the TCDI exhibits a greater capability of isolating the impact excitation than the traditional E-type isolator, thus verifying the whole-body vibration model for the roadheader and the matching strategy for the ECB isolator. This research can provide theoretical and practical references for the investigation of the dynamic behaviour of complex viscoelastic structures.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"44 9","pages":"54-61"},"PeriodicalIF":1.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41287538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-30DOI: 10.20855/ijav.2020.25.11572
K. Renji, Josephine Kelvina Florence
The sound radiation characteristics of a structure depend on its critical frequency. The expression for theoretically estimating the critical frequency of a composite cylindrical shell has not yet been reported. Thus, the practice is to use the expression for the composite panel for determining the critical frequency of a composite shell. In this work, critical frequencies of composite shells are investigated. As the critical frequency depends on the speed of the bending wave, an expression for the speed of the bending wave is first derived. It is seen that the curvature causes an increase in the speed of the bending wave and the orthotropic nature of the cylinder reduces the speed. An expression for the critical frequency of a composite cylindrical shell is then derived. The curvature causes a reduction in the critical frequency and the influence is significant in acoustically thick cylinders. Hence, the critical frequencies of such cylinders cannot be determined by using the expression for the panels. Effects of transverse shear deformation on the speed of the bending wave as well as the critical frequency are then investigated. Transverse shear deformation causes both reduction in the speed of the bending wave and an increase in the critical frequency. The orthotropic nature of the cylindrical shell increases the critical frequency further. The critical frequency of a typical composite cylinder is determined through a numerical simulation and the results are in agreement with the results obtained using the expressions derived. The critical frequency of a typical composite cylinder obtained through an experiment is presented. With this work, expressions for theoretically estimating the speeds of the bending waves and critical frequencies are derived for a composite cylindrical shell considering transverse shear deformation.
{"title":"Critical Frequencies of Composite Cylindrical Shells","authors":"K. Renji, Josephine Kelvina Florence","doi":"10.20855/ijav.2020.25.11572","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.11572","url":null,"abstract":"The sound radiation characteristics of a structure depend on its critical frequency. The expression for theoretically estimating the critical frequency of a composite cylindrical shell has not yet been reported. Thus, the practice is to use the expression for the composite panel for determining the critical frequency of a composite shell. In this work, critical frequencies of composite shells are investigated. As the critical frequency depends on the speed of the bending wave, an expression for the speed of the bending wave is first derived. It is seen that the curvature causes an increase in the speed of the bending wave and the orthotropic nature of the cylinder reduces the speed. An expression for the critical frequency of a composite cylindrical shell is then derived. The curvature causes a reduction in the critical frequency and the influence is significant in acoustically thick cylinders. Hence, the critical frequencies of such cylinders cannot be determined by using the expression for the panels. Effects of transverse shear deformation on the speed of the bending wave as well as the critical frequency are then investigated. Transverse shear deformation causes both reduction in the speed of the bending wave and an increase in the critical frequency. The orthotropic nature of the cylindrical shell increases the critical frequency further. The critical frequency of a typical composite cylinder is determined through a numerical simulation and the results are in agreement with the results obtained using the expressions derived. The critical frequency of a typical composite cylinder obtained through an experiment is presented. With this work, expressions for theoretically estimating the speeds of the bending waves and critical frequencies are derived for a composite cylindrical shell considering transverse shear deformation.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"79-87"},"PeriodicalIF":1.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48198217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-30DOI: 10.20855/ijav.2020.25.11549
Hyunsu Kim, Iljae Lee
The acoustic performance of Helmholtz resonators with different configurations in the presence of mean flow is experimentally investigated. The transmission loss of Helmholtz resonators is measured using a flow-impedance tube setup to identify mean flow effects. First, Helmholtz resonators under two different flow conditions, grazing and direct flow, are considered at Ma = 0.05 and 0.1. Then the impact of mean flow on the transmission loss of Helmholtz resonators with leakage holes is also demonstrated. For Helmholtz resonators with leakage holes, single peak of transmission loss is identified at Ma = 0.0 and 0.1. However, two peaks appear at Ma = 0.05 as the number of opening holes increases. The experimental results show that the effect of mean flow strongly depends on the configurations of Helmholtz resonators and the conditions of mean flow. Thus the variation of acoustic performance due to mean flow should be considered in the design of Helmholtz resonators.
{"title":"Effect of Flow on Various Helmholtz Resonators","authors":"Hyunsu Kim, Iljae Lee","doi":"10.20855/ijav.2020.25.11549","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.11549","url":null,"abstract":"The acoustic performance of Helmholtz resonators with different configurations in the presence of mean flow is experimentally investigated. The transmission loss of Helmholtz resonators is measured using a flow-impedance tube setup to identify mean flow effects. First, Helmholtz resonators under two different flow conditions, grazing and direct flow, are considered at Ma = 0.05 and 0.1. Then the impact of mean flow on the transmission loss of Helmholtz resonators with leakage holes is also demonstrated. For Helmholtz resonators with leakage holes, single peak of transmission loss is identified at Ma = 0.0 and 0.1. However, two peaks appear at Ma = 0.05 as the number of opening holes increases. The experimental results show that the effect of mean flow strongly depends on the configurations of Helmholtz resonators and the conditions of mean flow. Thus the variation of acoustic performance due to mean flow should be considered in the design of Helmholtz resonators.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"73-78"},"PeriodicalIF":1.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41515984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-30DOI: 10.20855/ijav.2020.25.11475
Erkut Yalçın, H. Bilal, Ayhan Yağcı, H. Erol
A Vibro-Acoustic Finite Element Method (FEM) model capable of calculating the transient sound pressure generated by the door slam of a vehicle was developed in this study. A design sensitivity analysis (DSA) was performed for investigating the effects of major design variables on the related sound quality metrics. The methodology was developed using a sedan-car and its FEM model. This paper shows that a Computer Aided Engineering (CAE) model can be used as a rather powerful tool for giving design change decisions for the door components from sound quality point of view during vehicle body development according to psychoacoustic parameters.
{"title":"A Numerical Approach for Sound Quality of Vehicle Doors","authors":"Erkut Yalçın, H. Bilal, Ayhan Yağcı, H. Erol","doi":"10.20855/ijav.2020.25.11475","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.11475","url":null,"abstract":"A Vibro-Acoustic Finite Element Method (FEM) model capable of calculating the transient sound pressure generated by the door slam of a vehicle was developed in this study. A design sensitivity analysis (DSA) was performed for investigating the effects of major design variables on the related sound quality metrics. The methodology was developed using a sedan-car and its FEM model. This paper shows that a Computer Aided Engineering (CAE) model can be used as a rather powerful tool for giving design change decisions for the door components from sound quality point of view during vehicle body development according to psychoacoustic parameters.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"9-16"},"PeriodicalIF":1.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45901708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-30DOI: 10.20855/ijav.2020.25.11580
Zhineng Zhang, Ling Zheng, T. Yan, Yao Wu
The nonlinear acoustic problem of a finite amplitude plane wave propagating along the axial direction in a traveling wave tube is studied. Based on the one-dimensional Westervelt equation, a one-dimensional nonlinear wave equation is derived in which the cross section of the traveling wave tube is considered. The two-order finite difference scheme is used to solve the nonlinear wave equation. The nonlinear propagation characteristics of a finite amplitude wave in the traveling wave tube is analyzed. In the expanding transition section, the acoustic pressure amplitude of the acoustic wave decreases with the increase of the cross-sectional area of the pipeline. The nonlinear characteristics of the acoustic wave show waveform distortion and harmonic growth. The waveform distortion becomes more serious in the rear of traveling wave tube than in the front of the tube. Considering the acoustic reflection condition at the mouth, the influence of differently shaped diffusion sections on the acoustic pressure distribution in the test section is investigated. The larger the change rate of the diffusion section in an area, the less amplitude of the sound pressure, and the nonlinear effect of the sound wave propagation is weakened. These nonlinear wave propagation characteristics in a travelling wave tube provide important guidance for both designing a uniform sound pressure distribution in the test section and determining the optimal measuring points for different sizes of structures in spacecraft.
{"title":"1D Numerical Study of Nonlinear Propagation of Finite Amplitude Waves in Traveling Wave Tubes with Varying Cross Section","authors":"Zhineng Zhang, Ling Zheng, T. Yan, Yao Wu","doi":"10.20855/ijav.2020.25.11580","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.11580","url":null,"abstract":"The nonlinear acoustic problem of a finite amplitude plane wave propagating along the axial direction in a traveling wave tube is studied. Based on the one-dimensional Westervelt equation, a one-dimensional nonlinear wave equation is derived in which the cross section of the traveling wave tube is considered. The two-order finite difference scheme is used to solve the nonlinear wave equation. The nonlinear propagation characteristics of a finite amplitude wave in the traveling wave tube is analyzed. In the expanding transition section, the acoustic pressure amplitude of the acoustic wave decreases with the increase of the cross-sectional area of the pipeline. The nonlinear characteristics of the acoustic wave show waveform distortion and harmonic growth. The waveform distortion becomes more serious in the rear of traveling wave tube than in the front of the tube. Considering the acoustic reflection condition at the mouth, the influence of differently shaped diffusion sections on the acoustic pressure distribution in the test section is investigated. The larger the change rate of the diffusion section in an area, the less amplitude of the sound pressure, and the nonlinear effect of the sound wave propagation is weakened. These nonlinear wave propagation characteristics in a travelling wave tube provide important guidance for both designing a uniform sound pressure distribution in the test section and determining the optimal measuring points for different sizes of structures in spacecraft.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"88-95"},"PeriodicalIF":1.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44024779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-30DOI: 10.20855/ijav.2020.25.11499
A. Rawat, V. Matsagar, A. K. Nagpal
A seismic analysis of ground-supported, three-dimensional (3-D) rigid-base steel cylindrical liquid storage tank is investigated, using a coupled acoustic-structural finite element (FE) method for fluid-structure interaction (FSI). In this method, the contained liquid in the tank is modelled using acoustic elements and the cylindrical tank is modelled using shell elements. The impulsive and convective terms are estimated separately by using the appropriate boundary conditions on the free surface of the liquid. The convergence and validation studies of the proposed FE model are conducted by comparing the results reported in the literature. The parametric studies are performed for rigid and flexible tanks for the varying slenderness of the open roof tanks. The sloshing displacement and base shear time history responses are evaluated for the 3-D tanks subjected to harmonic unidirectional ground motions. Further, the results are compared with the commonly used two and three lumped-mass models of the tank. Moreover, the seismic response quantities of the tank subjected simultaneously to the bi-directional horizontal components of earthquake ground motion are also investigated using the 3-D FE model, and the response quantities are compared with the lumped-mass models. The results obtained from the 3-D FE model and lumpedmass model are in close agreement. The average percentage difference in the 3-D FE and lumped-mass models for maximum sloshing displacement prediction is 15 percent to 20 percent and that for the base shear is about 4 to 10 percent, in the case of the uni-directional harmonic ground motions. It is concluded that the sloshing displacement is not affected by the tank flexibility, but the impulsive hydrodynamic pressure and the impulsive component of the base shear increases with the tank flexibility.
{"title":"Seismic Analysis of Steel Cylindrical Liquid Storage Tank Using Coupled Acoustic-Structural Finite Element Method For Fluid-Structure Interaction","authors":"A. Rawat, V. Matsagar, A. K. Nagpal","doi":"10.20855/ijav.2020.25.11499","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.11499","url":null,"abstract":"A seismic analysis of ground-supported, three-dimensional (3-D) rigid-base steel cylindrical liquid storage tank is investigated, using a coupled acoustic-structural finite element (FE) method for fluid-structure interaction (FSI). In this method, the contained liquid in the tank is modelled using acoustic elements and the cylindrical tank is modelled using shell elements. The impulsive and convective terms are estimated separately by using the appropriate boundary conditions on the free surface of the liquid. The convergence and validation studies of the proposed FE model are conducted by comparing the results reported in the literature. The parametric studies are performed for rigid and flexible tanks for the varying slenderness of the open roof tanks. The sloshing displacement and base shear time history responses are evaluated for the 3-D tanks subjected to harmonic unidirectional ground motions. Further, the results are compared with the commonly used two and three lumped-mass models of the tank. Moreover, the seismic response quantities of the tank subjected simultaneously to the bi-directional horizontal components of earthquake ground motion are also investigated using the 3-D FE model, and the response quantities are compared with the lumped-mass models. The results obtained from the 3-D FE model and lumpedmass model are in close agreement. The average percentage difference in the 3-D FE and lumped-mass models for maximum sloshing displacement prediction is 15 percent to 20 percent and that for the base shear is about 4 to 10 percent, in the case of the uni-directional harmonic ground motions. It is concluded that the sloshing displacement is not affected by the tank flexibility, but the impulsive hydrodynamic pressure and the impulsive component of the base shear increases with the tank flexibility.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"27-40"},"PeriodicalIF":1.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49573387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-30DOI: 10.20855/ijav.2020.25.11422
M. Coleman, L. McSweeney
While the Euler-Bernoulli beam is the most commonly utilized model in studying vibrating beams, one often requires a model that captures the additional effects of rotary inertia or deformation due to shear. The Rayleigh beam improves upon the Euler-Bernoulli by including the former effect, while the shear beam is an improvement that includes the latter. While all of these problems have been well studied when subject to energy-conserving boundary conditions, none have been solved for the case of boundary damping. We compute the exact frequency equations for the Rayleigh and shear beams, subject to boundary damping and, in the process, we find interesting connections between the two models, despite their being very different.
{"title":"The Exact Frequency Equations for the Rayleigh and Shear Beams with Boundary Damping","authors":"M. Coleman, L. McSweeney","doi":"10.20855/ijav.2020.25.11422","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.11422","url":null,"abstract":"While the Euler-Bernoulli beam is the most commonly utilized model in studying vibrating beams, one often requires a model that captures the additional effects of rotary inertia or deformation due to shear. The Rayleigh beam improves upon the Euler-Bernoulli by including the former effect, while the shear beam is an improvement that includes the latter. While all of these problems have been well studied when subject to energy-conserving boundary conditions, none have been solved for the case of boundary damping. We compute the exact frequency equations for the Rayleigh and shear beams, subject to boundary damping and, in the process, we find interesting connections between the two models, despite their being very different.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"3-8"},"PeriodicalIF":1.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47481091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-30DOI: 10.20855/ijav.2020.25.11535
Younes Ait Elmaati, L. Bahir, K. Faitah
In this paper, a strategy is proposed to deal with the total pitch actuator failure in the modern wind turbines. The fault is firstly detected using a suitable proportional residual which rises when the measured rotor dynamics match the pure wind turbulence driven dynamics of the reference model. The fault tolerant control method relies on the distribution of the control signal on the remaining actuators, namely the generator torque and the yaw actuator. The pseudo inverse is applied on the residual between the measured and the nominal dynamics of the tower and the rotor. The distributed control signal is then suitably filtered in order to match the production and the safety objectives. Firstly, the generator torque filter comes to minimize the high frequencies on the rotor speed for a stable production to the grid. Secondly, the band pass yaw angle filter comes to minimize the mean yaw misalignment between the yaw nacelle and the wind direction. The method shows good dynamics reconstruction capabilities while keeping a stable production within a safe environment.
{"title":"The Rotor and Tower Vibrations Damping Monitoring in the Case of Total Pitch Servomotors Failure","authors":"Younes Ait Elmaati, L. Bahir, K. Faitah","doi":"10.20855/ijav.2020.25.11535","DOIUrl":"https://doi.org/10.20855/ijav.2020.25.11535","url":null,"abstract":"In this paper, a strategy is proposed to deal with the total pitch actuator failure in the modern wind turbines. The fault is firstly detected using a suitable proportional residual which rises when the measured rotor dynamics match the pure wind turbulence driven dynamics of the reference model. The fault tolerant control method relies on the distribution of the control signal on the remaining actuators, namely the generator torque and the yaw actuator. The pseudo inverse is applied on the residual between the measured and the nominal dynamics of the tower and the rotor. The distributed control signal is then suitably filtered in order to match the production and the safety objectives. Firstly, the generator torque filter comes to minimize the high frequencies on the rotor speed for a stable production to the grid. Secondly, the band pass yaw angle filter comes to minimize the mean yaw misalignment between the yaw nacelle and the wind direction. The method shows good dynamics reconstruction capabilities while keeping a stable production within a safe environment.","PeriodicalId":49185,"journal":{"name":"International Journal of Acoustics and Vibration","volume":"25 1","pages":"62-72"},"PeriodicalIF":1.0,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48428668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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