Junjiao Zhang, G. Shen, Yongna Shen, Yilin Yuan, Wenjun Zhang, Juanjuan Li
The reducer is a very important mechanical part of large-scale rotating amusement devices such as the popular big pendulum. It constantly adjusts the speed during the operation of the device and bears different loads. Due to it is difficult to disassemble after its installation, there is no effective method for the detection or online monitoring. Acoustic emission (AE) technology is an effective tool for condition monitoring and fault diagnosis of rotating machinery. AE tests for the reducer were studied in the lab. The effects of speed change and load change on the AE signals of the reducer are respectively obtained. The filed test on reducers of a big pendulum in the amusement park was carried out. The AE characteristics of the reducer with the movement of the pendulum were analyzed. The results show that AE technology will play an important role in the health monitoring of the reducer on amusement devices.
{"title":"Research on the Application of Acoustic Emission Technology in the Health Monitoring of the Reducers on Amusement Devices","authors":"Junjiao Zhang, G. Shen, Yongna Shen, Yilin Yuan, Wenjun Zhang, Juanjuan Li","doi":"10.1115/imece2021-70743","DOIUrl":"https://doi.org/10.1115/imece2021-70743","url":null,"abstract":"\u0000 The reducer is a very important mechanical part of large-scale rotating amusement devices such as the popular big pendulum. It constantly adjusts the speed during the operation of the device and bears different loads. Due to it is difficult to disassemble after its installation, there is no effective method for the detection or online monitoring. Acoustic emission (AE) technology is an effective tool for condition monitoring and fault diagnosis of rotating machinery. AE tests for the reducer were studied in the lab. The effects of speed change and load change on the AE signals of the reducer are respectively obtained. The filed test on reducers of a big pendulum in the amusement park was carried out. The AE characteristics of the reducer with the movement of the pendulum were analyzed. The results show that AE technology will play an important role in the health monitoring of the reducer on amusement devices.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77557999","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}
Mid-frequency transient vibration analysis of flexible structures plays an important role in a variety of engineering applications. In a mid-frequency region, neither low-frequency methods like the finite element analysis (FEA) nor high-frequency methods like the statistical energy analysis (SEA) are directly applicable to transient vibration analysis. For optimal design of multi-body structures, a mid-frequency transient vibration analysis tool with a good balance of accuracy and efficiency in computation is in demand. In this paper, to address the aforementioned issue, a model reduction method is developed for mid-frequency transient vibration analysis of beam structures. The method is based on the augmented distributed transfer function method (augmented DTFM). In this work, the augmented DTFM is modified for model reduction in mid-frequency analysis of beam structures, which is an extension of the authors’ previous effort. The idea behind this approach is to properly select several modes in the low-frequency region and a number of modes in a mid-frequency region that encompasses the excitation frequency spectrum, from the infinite series given by the augmented DTFM. This way, a reduced model of a beam structure for mid-frequency transient analysis is systematically obtained. The proposed model reduction method is validated in numerical examples, where the augmented method is compared with other methods, including the FEA. The accuracy and efficiency of the new method on the computation of transient displacement and shear force is demonstrated. As shown in the simulation results, a proper balance between accuracy and efficiency in model reduction can be achieved by the augmented DTFM. The computation savings by the proposed method, compared with the traditional numerical methods, can be of several orders of magnitude.
{"title":"Model Reduction for Mid-Frequency Transient Vibration Analysis of Beam Structures by the Augmented DTFM","authors":"Yichi Zhang, Bingen Yang","doi":"10.1115/imece2021-69979","DOIUrl":"https://doi.org/10.1115/imece2021-69979","url":null,"abstract":"\u0000 Mid-frequency transient vibration analysis of flexible structures plays an important role in a variety of engineering applications. In a mid-frequency region, neither low-frequency methods like the finite element analysis (FEA) nor high-frequency methods like the statistical energy analysis (SEA) are directly applicable to transient vibration analysis. For optimal design of multi-body structures, a mid-frequency transient vibration analysis tool with a good balance of accuracy and efficiency in computation is in demand. In this paper, to address the aforementioned issue, a model reduction method is developed for mid-frequency transient vibration analysis of beam structures. The method is based on the augmented distributed transfer function method (augmented DTFM).\u0000 In this work, the augmented DTFM is modified for model reduction in mid-frequency analysis of beam structures, which is an extension of the authors’ previous effort. The idea behind this approach is to properly select several modes in the low-frequency region and a number of modes in a mid-frequency region that encompasses the excitation frequency spectrum, from the infinite series given by the augmented DTFM. This way, a reduced model of a beam structure for mid-frequency transient analysis is systematically obtained. The proposed model reduction method is validated in numerical examples, where the augmented method is compared with other methods, including the FEA. The accuracy and efficiency of the new method on the computation of transient displacement and shear force is demonstrated. As shown in the simulation results, a proper balance between accuracy and efficiency in model reduction can be achieved by the augmented DTFM. The computation savings by the proposed method, compared with the traditional numerical methods, can be of several orders of magnitude.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80253179","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}
Jiamin Yao, Weihua Zhuang, Jinyang Feng, Yang Zhao, Shaokai Wang, Shuqing Wu, F. Fang, Tian-chu Li
Absolute gravimeters have been widely used as an important instrument in geological exploration and geophysics. To achieve a required measurement precision, it is necessary to integrate a vertical vibration isolator with ultra-low resonance frequency into the gravimeter. In this paper, an active vibration isolator designed on the basis of a BM-10 passive vibration isolation platform is presented. In the isolator, a seismometer placed next to the payload on the same plate outputs a voltage signal proportional to the payload’s velocity. According to this signal, a feedback circuit based on a PID controller controls two identical voice coil actuators to drive the platform synchronously. In this way, the vibration of the payload is suppressed. The BM-10 platform has 6-DOF passive vibration isolation originally, but its horizontal vibration isolation is proved unnecessary or even harmful in absolute gravimetry. Hence, two linear bushings are applied as a horizontal constraint to ensure that the payload only moves vertically in a straight line. Experiments show the resonance period of the isolator reaches approximately 88 s. In addition, the active vibration isolator has shown a much better performance for vibrations at low frequency than the passive isolator. In the future, the vibration isolator will be improved and then be integrated in the NIM-AGRb-1 atom-interferometry absolute gravimeter for the evaluation of its performance.
{"title":"An Ultra-Low-Frequency Active Vertical Vibration Isolator With Horizontal Constraints for Absolute Gravimetry","authors":"Jiamin Yao, Weihua Zhuang, Jinyang Feng, Yang Zhao, Shaokai Wang, Shuqing Wu, F. Fang, Tian-chu Li","doi":"10.1115/imece2021-68008","DOIUrl":"https://doi.org/10.1115/imece2021-68008","url":null,"abstract":"\u0000 Absolute gravimeters have been widely used as an important instrument in geological exploration and geophysics. To achieve a required measurement precision, it is necessary to integrate a vertical vibration isolator with ultra-low resonance frequency into the gravimeter. In this paper, an active vibration isolator designed on the basis of a BM-10 passive vibration isolation platform is presented. In the isolator, a seismometer placed next to the payload on the same plate outputs a voltage signal proportional to the payload’s velocity. According to this signal, a feedback circuit based on a PID controller controls two identical voice coil actuators to drive the platform synchronously. In this way, the vibration of the payload is suppressed. The BM-10 platform has 6-DOF passive vibration isolation originally, but its horizontal vibration isolation is proved unnecessary or even harmful in absolute gravimetry. Hence, two linear bushings are applied as a horizontal constraint to ensure that the payload only moves vertically in a straight line. Experiments show the resonance period of the isolator reaches approximately 88 s. In addition, the active vibration isolator has shown a much better performance for vibrations at low frequency than the passive isolator. In the future, the vibration isolator will be improved and then be integrated in the NIM-AGRb-1 atom-interferometry absolute gravimeter for the evaluation of its performance.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85032916","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 suggests a comprehensive case study of acoustic radiation from ribbed plate with inner resonance. Based on explicit design rules and homogenized model for flexural waves, it shows that bending waves propagation significantly differs from classical models in terms of wavenumber features in the neighborhood of local resonances, and comments on the influence of the atypical structural response on the radiated pressure field. The investigation of the acoustic radiation from an infinite and finite ribbed plate is proposed. The trend of the resulting radiated pressure fields from the homogenized model matches with classical models outside frequency bands associated with local resonance, however inner resonance yields additional frequency ranges in which acoustic radiation is either strongly reduced or enhanced. For both mechanical and acoustic responses, theoretical results are successfully compared with finite element method. Further consideration may focus on the radiation mechanisms with coupled bending and torsion in the stiffner.
{"title":"Sound Radiation of Locally Resonant Unidirectionally Ribbed Plates","authors":"P. Fossat, M. Ichchou","doi":"10.1115/imece2021-70987","DOIUrl":"https://doi.org/10.1115/imece2021-70987","url":null,"abstract":"\u0000 This paper suggests a comprehensive case study of acoustic radiation from ribbed plate with inner resonance. Based on explicit design rules and homogenized model for flexural waves, it shows that bending waves propagation significantly differs from classical models in terms of wavenumber features in the neighborhood of local resonances, and comments on the influence of the atypical structural response on the radiated pressure field. The investigation of the acoustic radiation from an infinite and finite ribbed plate is proposed. The trend of the resulting radiated pressure fields from the homogenized model matches with classical models outside frequency bands associated with local resonance, however inner resonance yields additional frequency ranges in which acoustic radiation is either strongly reduced or enhanced. For both mechanical and acoustic responses, theoretical results are successfully compared with finite element method. Further consideration may focus on the radiation mechanisms with coupled bending and torsion in the stiffner.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89549228","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}
A two-dimensional infinite length porous slab is employed to simulate biomimetic porous scaffold. The pores of slab are saturated with a relatively low and high viscous fluids such as air and bone marrow. Ultrasonic waves based on the Biot-JKD formulation travel through the porous slab and create viscous exchanges between the skeletal frame and the fluid. The Biot-JKD formulation focuses on the parameters, biomarkers of the biomimetic porous scaffold, which are sensitive to the transmission and reflection signals. These parameters include porosity, tortuosity, viscous characteristic length, Young’s modulus, and Poisson’s ratio. An artificial neural network (ANN) based on a set of the biomarkers is rendered to model the transmitted and reflected waves from the porous slab. The validation of the proposed analytical approach and released artificial neural network is evaluated by the pertinent literature. The output of the artificial neural network, the transmitted-reflected waves, is inversely applied to the analytical expression to estimate the biomarkers associated with bone regeneration. The results show that for a medium filled with a relatively high viscous fluid the longitudinal waves are more prone to estimate mechanical properties of the medium such as Young’s modulus and Poisson’s ratio while the transverse waves, in addition to longitudinal waves, are essential to estimate the physical properties of the medium including porosity, tortuosity, and viscous characteristic length. Furthermore, it is also concluded that for the medium filled with a relatively low viscous fluid such as air the longitudinal waves alone is able to estimate the biomarkers, which reduce significantly the computational efforts.
{"title":"Ultrasonic Characterization of Biomimetic Porous Scaffold Using Machine Learning: Application of Biot’s Theory","authors":"M. Hodaei, P. Maghoul","doi":"10.1115/imece2021-72746","DOIUrl":"https://doi.org/10.1115/imece2021-72746","url":null,"abstract":"\u0000 A two-dimensional infinite length porous slab is employed to simulate biomimetic porous scaffold. The pores of slab are saturated with a relatively low and high viscous fluids such as air and bone marrow. Ultrasonic waves based on the Biot-JKD formulation travel through the porous slab and create viscous exchanges between the skeletal frame and the fluid. The Biot-JKD formulation focuses on the parameters, biomarkers of the biomimetic porous scaffold, which are sensitive to the transmission and reflection signals. These parameters include porosity, tortuosity, viscous characteristic length, Young’s modulus, and Poisson’s ratio. An artificial neural network (ANN) based on a set of the biomarkers is rendered to model the transmitted and reflected waves from the porous slab. The validation of the proposed analytical approach and released artificial neural network is evaluated by the pertinent literature. The output of the artificial neural network, the transmitted-reflected waves, is inversely applied to the analytical expression to estimate the biomarkers associated with bone regeneration. The results show that for a medium filled with a relatively high viscous fluid the longitudinal waves are more prone to estimate mechanical properties of the medium such as Young’s modulus and Poisson’s ratio while the transverse waves, in addition to longitudinal waves, are essential to estimate the physical properties of the medium including porosity, tortuosity, and viscous characteristic length. Furthermore, it is also concluded that for the medium filled with a relatively low viscous fluid such as air the longitudinal waves alone is able to estimate the biomarkers, which reduce significantly the computational efforts.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73655208","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}
Mario Escarcega, Meghan Cephus, Skyler Hughes, Nakii Tsosie, Kimberly Kelso, Raechelle Sandoval, A. Ebrahimkhanlou
This paper explores the use of acoustic-based structural health monitoring (SHM) in lunar habitats to detect damage and failure in pipelines used for resource transportation. Acoustic-based SHM on Earth is a well-studied field of research. Various studies validate the effectiveness of acoustic-based SHM to detect, locate, and characterize damage in pipelines. Relevant literature shows that little to no research has been conducted on SHM regarding simulated lunar pipelines. In this paper, acoustic emission (AE) waveforms were collected and analyzed for aluminum pipe sections that were damaged from three separately simulated lunar conditions. Experiments simulating lunar regolith abrasion, internal galvanic corrosion, and irradiation were conducted on aluminum pipes. Pipes on the lunar surface will be constantly exposed to radiation, abrasion, and corrosion. As such, it is important to detect, localize, and predict damage resulting from these lunar hazards. The waveform data were clustered based on hit-driven properties. These clusters showed distinct differences between the datasets, which allowed for comparison and characterization of the data. It was found that variations in cluster shape and placement in peak, centroid, and average frequency could reliably distinguish between corrosive and abrasive processes. Understanding the differences in the data that contribute to distinctions between event types, and those that do not, will enable AE monitoring systems to better identify, characterize, and predict lunar pipeline failure.
{"title":"Acoustic Emission-Based Structural Health Monitoring for Future Lunar Pipelines","authors":"Mario Escarcega, Meghan Cephus, Skyler Hughes, Nakii Tsosie, Kimberly Kelso, Raechelle Sandoval, A. Ebrahimkhanlou","doi":"10.1115/imece2021-71429","DOIUrl":"https://doi.org/10.1115/imece2021-71429","url":null,"abstract":"\u0000 This paper explores the use of acoustic-based structural health monitoring (SHM) in lunar habitats to detect damage and failure in pipelines used for resource transportation. Acoustic-based SHM on Earth is a well-studied field of research. Various studies validate the effectiveness of acoustic-based SHM to detect, locate, and characterize damage in pipelines. Relevant literature shows that little to no research has been conducted on SHM regarding simulated lunar pipelines. In this paper, acoustic emission (AE) waveforms were collected and analyzed for aluminum pipe sections that were damaged from three separately simulated lunar conditions. Experiments simulating lunar regolith abrasion, internal galvanic corrosion, and irradiation were conducted on aluminum pipes. Pipes on the lunar surface will be constantly exposed to radiation, abrasion, and corrosion. As such, it is important to detect, localize, and predict damage resulting from these lunar hazards. The waveform data were clustered based on hit-driven properties. These clusters showed distinct differences between the datasets, which allowed for comparison and characterization of the data. It was found that variations in cluster shape and placement in peak, centroid, and average frequency could reliably distinguish between corrosive and abrasive processes. Understanding the differences in the data that contribute to distinctions between event types, and those that do not, will enable AE monitoring systems to better identify, characterize, and predict lunar pipeline failure.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"88 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82090139","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 flow surrounding the propeller of an electric fan contributes significantly to the noise emitted by low-pressure electronic fans designed to cool electronic equipment such as desktop computers. This study characterizes fan noise based on modification of geometrical features such as its hub diameter, blade length, blade thickness, blade angle of attack and number of blades. Computational Fluid Dynamics and Computational Aeroacoustics simulations were employed to analyze sound pressure level on the fan rotor. A commercially available computer cooling fan was selected as a reference fan. Two constant rotational speeds were tested, 2,400 rpm and 4,500 rpm, yielding OASPL of 31.94 dB and 48.99 dB, respectively. The sound pressure levels visualized from the reference fan were within the range of noise emission advertised by two manufacturers for the same size of fan, with number of blades and rated voltage. Velocity magnitude profiles and pressure profile distributions were also generated to visualize the flow patterns and validate aerodynamic theories citing turbulent flow in the vicinity of the rotor, characterized by a vortex field, wakes and eddies in the Trailing Edge. A reduction in hub diameter and an increase in the blade’s thickness resulted in considerable noise reduction. Consequently, an improved fan geometry was created by superimposing these design modifications yielding a 5.02 dB and 3.53 dB noise reduction for the two respective rotational speeds.
{"title":"Characterization of Electric Fan Noise Generation Due to Blade Geometry","authors":"Liliosa-Eyang Cole, F. Barez","doi":"10.1115/imece2021-68201","DOIUrl":"https://doi.org/10.1115/imece2021-68201","url":null,"abstract":"\u0000 The flow surrounding the propeller of an electric fan contributes significantly to the noise emitted by low-pressure electronic fans designed to cool electronic equipment such as desktop computers. This study characterizes fan noise based on modification of geometrical features such as its hub diameter, blade length, blade thickness, blade angle of attack and number of blades.\u0000 Computational Fluid Dynamics and Computational Aeroacoustics simulations were employed to analyze sound pressure level on the fan rotor. A commercially available computer cooling fan was selected as a reference fan. Two constant rotational speeds were tested, 2,400 rpm and 4,500 rpm, yielding OASPL of 31.94 dB and 48.99 dB, respectively. The sound pressure levels visualized from the reference fan were within the range of noise emission advertised by two manufacturers for the same size of fan, with number of blades and rated voltage. Velocity magnitude profiles and pressure profile distributions were also generated to visualize the flow patterns and validate aerodynamic theories citing turbulent flow in the vicinity of the rotor, characterized by a vortex field, wakes and eddies in the Trailing Edge.\u0000 A reduction in hub diameter and an increase in the blade’s thickness resulted in considerable noise reduction. Consequently, an improved fan geometry was created by superimposing these design modifications yielding a 5.02 dB and 3.53 dB noise reduction for the two respective rotational speeds.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77823224","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}
C. Dumm, Anna C. Hiers, David B. Maupin, Marianne E. Cites, G. Klinzing, Carey D. Balaban, J. Vipperman
High-frequency ensonification of the head has the potential to excite unusual and difficult-to-measure internal vibration behavior. The head is a complex, interconnected vibroacoustic volume filled with and bounded by air, fluids, soft tissue structures, and bone. A literature gap exists in assessment of how ultrasonic vibrations of relatively low frequency and low amplitude might propagate within the skull and cranial contents of humans and cynomolgus macaque monkeys. Ultrasonic emitters are ubiquitous in modern society, including uses in vehicular proximity sensing, room occupancy monitoring, pest control, and industrial cleaning. This investigation uses finite-element techniques to examine vibro-acoustic behaviors of the skull and structures within the cranial cavity in the context of excitation by ultrasonic signals. Previous analysis procedures designed for assessment of possible resonant phenomena in the auditory and vestibular systems are revised and extended to assessment of the skull and the contents of the cranial cavity of humans and macaques, including volumes of cerebrospinal fluid (CSF) and the brain. Results include identification of cranial regions that may experience high-amplitude vibrations in response to ultrasonic excitation. These methods and results are useful for assessing how a wide variety of devices, including communications equipment, might produce biological effects.
{"title":"Vibro-Acoustic Ultrasonic Resonant Behavior in Skull and Cranial Contents","authors":"C. Dumm, Anna C. Hiers, David B. Maupin, Marianne E. Cites, G. Klinzing, Carey D. Balaban, J. Vipperman","doi":"10.1115/imece2021-70038","DOIUrl":"https://doi.org/10.1115/imece2021-70038","url":null,"abstract":"\u0000 High-frequency ensonification of the head has the potential to excite unusual and difficult-to-measure internal vibration behavior. The head is a complex, interconnected vibroacoustic volume filled with and bounded by air, fluids, soft tissue structures, and bone. A literature gap exists in assessment of how ultrasonic vibrations of relatively low frequency and low amplitude might propagate within the skull and cranial contents of humans and cynomolgus macaque monkeys. Ultrasonic emitters are ubiquitous in modern society, including uses in vehicular proximity sensing, room occupancy monitoring, pest control, and industrial cleaning. This investigation uses finite-element techniques to examine vibro-acoustic behaviors of the skull and structures within the cranial cavity in the context of excitation by ultrasonic signals. Previous analysis procedures designed for assessment of possible resonant phenomena in the auditory and vestibular systems are revised and extended to assessment of the skull and the contents of the cranial cavity of humans and macaques, including volumes of cerebrospinal fluid (CSF) and the brain. Results include identification of cranial regions that may experience high-amplitude vibrations in response to ultrasonic excitation. These methods and results are useful for assessing how a wide variety of devices, including communications equipment, might produce biological effects.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82489837","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 front matter for this proceedings is available by clicking on the PDF icon.
通过点击PDF图标可获得本次会议的主题。
{"title":"IMECE2021 Front Matter","authors":"","doi":"10.1115/imece2021-fm1","DOIUrl":"https://doi.org/10.1115/imece2021-fm1","url":null,"abstract":"\u0000 The front matter for this proceedings is available by clicking on the PDF icon.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77304906","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}
Piezoelectric materials can be introduced as the additional components into the periodic structures as they can couple the mechanical and electric fields. However, the added mass is always constrained in practical engineering. A method is needed to guide how to posit the piezoelectric materials on the host structure under the mass limit. In this work, we develop a numerical method to determine the best distribution of piezoelectric materials on the host structure in order to control the wave propagation in the periodic structures. This is based on the fact that the propagation properties of the waves in the mechanical field can be regulated by electric impedance shunted to the piezoelectric materials. The coupling strength between the mechanical field and the electric field is quantified by the wave electromechanical coupling factor (WEMCF). It is related to the geometric of the piezoelectric materials only. As the periodic structures are constructed by the identical unit cell, the aim is to design the distribution of the piezoelectric materials on the unit cell. There is no constrain on the shape of piezoelectric materials in the optimized method, only the overall mass is limited. A linear weighing of stress components is proposed as the criterion to determine the priority of locations for piezoelectric materials. In the proposed method, the piezoelectric materials are introduced to the FE model by adding the additional piezoelectric element layers on the host structure. Details for handling polarization direction, electrode connection and the electric circuit parameters selection are also presented. A 1D thin-wall box beam is taken as the application example. Results show that the Bragg band gap can be adjusted to cover the target frequency range under the optimization design with the 10% mass limitation.
{"title":"Topological Optimization of Piezoelectric Materials for the Control of Wave Propagation in Periodic Structures","authors":"Jiahui Shi, Yu Fan, Lin Li","doi":"10.1115/imece2021-70964","DOIUrl":"https://doi.org/10.1115/imece2021-70964","url":null,"abstract":"\u0000 Piezoelectric materials can be introduced as the additional components into the periodic structures as they can couple the mechanical and electric fields. However, the added mass is always constrained in practical engineering. A method is needed to guide how to posit the piezoelectric materials on the host structure under the mass limit. In this work, we develop a numerical method to determine the best distribution of piezoelectric materials on the host structure in order to control the wave propagation in the periodic structures. This is based on the fact that the propagation properties of the waves in the mechanical field can be regulated by electric impedance shunted to the piezoelectric materials. The coupling strength between the mechanical field and the electric field is quantified by the wave electromechanical coupling factor (WEMCF). It is related to the geometric of the piezoelectric materials only. As the periodic structures are constructed by the identical unit cell, the aim is to design the distribution of the piezoelectric materials on the unit cell. There is no constrain on the shape of piezoelectric materials in the optimized method, only the overall mass is limited. A linear weighing of stress components is proposed as the criterion to determine the priority of locations for piezoelectric materials. In the proposed method, the piezoelectric materials are introduced to the FE model by adding the additional piezoelectric element layers on the host structure. Details for handling polarization direction, electrode connection and the electric circuit parameters selection are also presented. A 1D thin-wall box beam is taken as the application example. Results show that the Bragg band gap can be adjusted to cover the target frequency range under the optimization design with the 10% mass limitation.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76651146","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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