Xu Long, Jiaqi Zhu, Yutai Su, K. Siow, Chuantong Chen
Polymer-bonded explosive (PBX), also known as plastic-bonded explosive, is a typical kind of explosive powder with the synthetic polymer bonded together explosive composite materials. It has excellent explosion performance and thus is widely applied in the military and civilian industries. The PBX mechanical properties exhibit high sensitivities to the action of various types of loads, which is closely related to microscopic damage mechanisms within the material. The applied loads vary considerably, with amplitudes ranging from a few MPa to as high as several tens of GPa and durations lasting from the order of μs to ms. The cracking evolution is essential to the PBX applications in a strict control manner. However, PBXs are dangerous energy-bearing materials, and the mechanical experiments to measure their mechanical properties are costly and also challenging. Therefore, theoretical analysis and numerical simulation are anticipated to explore the sensitivities of PBX mechanical properties and also the influence of crack evolution. This paper will simulate numerically the process of work done of PBX explosive gas by fracture phase-field method, which reveals the typical microscopical mechanism of crack evolution and establish a computational model for crack propagation under the coupled thermomechanical effects.
{"title":"Phase-Field Modelling for Crack Evolution of PBX Under Thermomechanical Loadings","authors":"Xu Long, Jiaqi Zhu, Yutai Su, K. Siow, Chuantong Chen","doi":"10.1115/imece2022-96468","DOIUrl":"https://doi.org/10.1115/imece2022-96468","url":null,"abstract":"\u0000 Polymer-bonded explosive (PBX), also known as plastic-bonded explosive, is a typical kind of explosive powder with the synthetic polymer bonded together explosive composite materials. It has excellent explosion performance and thus is widely applied in the military and civilian industries. The PBX mechanical properties exhibit high sensitivities to the action of various types of loads, which is closely related to microscopic damage mechanisms within the material. The applied loads vary considerably, with amplitudes ranging from a few MPa to as high as several tens of GPa and durations lasting from the order of μs to ms. The cracking evolution is essential to the PBX applications in a strict control manner. However, PBXs are dangerous energy-bearing materials, and the mechanical experiments to measure their mechanical properties are costly and also challenging. Therefore, theoretical analysis and numerical simulation are anticipated to explore the sensitivities of PBX mechanical properties and also the influence of crack evolution. This paper will simulate numerically the process of work done of PBX explosive gas by fracture phase-field method, which reveals the typical microscopical mechanism of crack evolution and establish a computational model for crack propagation under the coupled thermomechanical effects.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89822517","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}
J. Hirokawa, O. Nishimura, Y. Hisakuni, A. Kano, Hideaki Uehara, T. Monda, K. Hirohata, Toshinobu Ito, Shohei Takami, T. Orikasa, Kiyokazu Sato
Acoustic emission (AE) measurement is a non-destructive testing method that can detect high-frequency elastic waves generated by mechanical events inside an object, and is able to localize the wave source by using multiple sensors. In order to determine the mechanism causing the quench phenomenon in superconducting coil, we applied the AE method to a small ellipse-shaped coil in a training experiment. Six AE sensors were installed on the coil surface before the coil was cooled to 4 K in a vacuum vessel and excited. The current to the coil was controlled to produce a gradual increase until the quench occurred. The entire training experiment ended after over 10 quenches and all AE events that occurred in each training cycle were measured. The location of the AE source inside the coil was calculated from the difference in arrival time between sensors, and the results were plotted on an expansion plan of the coil. High-amplitude AE events appeared in areas assumed to have sufficiently high internal stress to cause concentration of strain energy.
{"title":"Acoustic Emission Measurement and Location Analysis of Acoustic Emission Source for Superconducting Coil Quench During Training","authors":"J. Hirokawa, O. Nishimura, Y. Hisakuni, A. Kano, Hideaki Uehara, T. Monda, K. Hirohata, Toshinobu Ito, Shohei Takami, T. Orikasa, Kiyokazu Sato","doi":"10.1115/imece2022-91393","DOIUrl":"https://doi.org/10.1115/imece2022-91393","url":null,"abstract":"\u0000 Acoustic emission (AE) measurement is a non-destructive testing method that can detect high-frequency elastic waves generated by mechanical events inside an object, and is able to localize the wave source by using multiple sensors. In order to determine the mechanism causing the quench phenomenon in superconducting coil, we applied the AE method to a small ellipse-shaped coil in a training experiment. Six AE sensors were installed on the coil surface before the coil was cooled to 4 K in a vacuum vessel and excited. The current to the coil was controlled to produce a gradual increase until the quench occurred. The entire training experiment ended after over 10 quenches and all AE events that occurred in each training cycle were measured. The location of the AE source inside the coil was calculated from the difference in arrival time between sensors, and the results were plotted on an expansion plan of the coil. High-amplitude AE events appeared in areas assumed to have sufficiently high internal stress to cause concentration of strain energy.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85430219","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}
Particle manipulation and patterning have gained tremendous attention in chemical, biomedical, and manufacturing studies. Hydrogels are usually used for applications in soft robots, biosensing, as well as tissue engineering. In this study, we investigated a nanoparticle manipulation method based on standing surface acoustic waves (SAWs). The SAW device consists of a piezoelectric lithium niobate (LiNbO3) substrate with a pair of interdigital transducers (IDTs). Finite element simulations were performed to understand the mechanisms of the SAW device as well as reveal the acoustic pressure field and electric potential field generated by the device. In addition to numerical studies, proof-of-concept experiments were performed by using a fabricated SAW device for patterning both silicon dioxide (SiO2) nanoparticles and multi-walled carbon nanotubes (MWCNTs) in a hydrogel solution.
{"title":"Alignment of Nanomaterials in Hydrogels by Using Standing Surface Acoustic Wave-Enable","authors":"Jiali Li, Luyu Bo, Teng Li, Zhenhua Tian","doi":"10.1115/imece2022-97095","DOIUrl":"https://doi.org/10.1115/imece2022-97095","url":null,"abstract":"\u0000 Particle manipulation and patterning have gained tremendous attention in chemical, biomedical, and manufacturing studies. Hydrogels are usually used for applications in soft robots, biosensing, as well as tissue engineering. In this study, we investigated a nanoparticle manipulation method based on standing surface acoustic waves (SAWs). The SAW device consists of a piezoelectric lithium niobate (LiNbO3) substrate with a pair of interdigital transducers (IDTs). Finite element simulations were performed to understand the mechanisms of the SAW device as well as reveal the acoustic pressure field and electric potential field generated by the device. In addition to numerical studies, proof-of-concept experiments were performed by using a fabricated SAW device for patterning both silicon dioxide (SiO2) nanoparticles and multi-walled carbon nanotubes (MWCNTs) in a hydrogel solution.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"106 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87900505","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}
Steel strands have the advantages of good bending performance, strong impact resistance, stable and reliable operation, etc. As a load-bearing structure, the health of steel strands directly affects the stability and safety of the entire structure. Therefore, detecting the damage to in-service steel strands is extremely important. Due to the influence of the helical structure, the contact effect between the wires, and the influence of the applied load, it is difficult to solve the wave problem of the steel strands using the governing equations and boundary conditions from a purely theoretical point of view. The Floquet Boundary Conditions (Floquet BC) method can replace the whole with a single repeatable substructure without rewriting the equilibrium equation, which is more general and simpler than the SAFE method. The advantage of Floquet BC is that only the propagation term is considered, and it is very suitable for irregular waveguides such as steel strands. In this paper, the Floquet BC method is used to analyze the dispersion characteristics of the helical curved rod and the steel strands in the torsional coordinate system, and the results obtained are the same as those obtained by the SAFE method.
{"title":"Investigation on Dispersion Characteristics of Elastic Waves in Steel Strands Based on Floquet Boundary Conditions Method","authors":"Hongyan Zhang, Jian Li, Shili Chen, Yang Liu","doi":"10.1115/imece2022-96717","DOIUrl":"https://doi.org/10.1115/imece2022-96717","url":null,"abstract":"\u0000 Steel strands have the advantages of good bending performance, strong impact resistance, stable and reliable operation, etc. As a load-bearing structure, the health of steel strands directly affects the stability and safety of the entire structure. Therefore, detecting the damage to in-service steel strands is extremely important. Due to the influence of the helical structure, the contact effect between the wires, and the influence of the applied load, it is difficult to solve the wave problem of the steel strands using the governing equations and boundary conditions from a purely theoretical point of view. The Floquet Boundary Conditions (Floquet BC) method can replace the whole with a single repeatable substructure without rewriting the equilibrium equation, which is more general and simpler than the SAFE method. The advantage of Floquet BC is that only the propagation term is considered, and it is very suitable for irregular waveguides such as steel strands. In this paper, the Floquet BC method is used to analyze the dispersion characteristics of the helical curved rod and the steel strands in the torsional coordinate system, and the results obtained are the same as those obtained by the SAFE method.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74966762","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 fatigue test employing vibration-based fatigue known as the “Free-Free” has been in use inside the Turbine Engine Fatigue Facility (TEFF) of the Air Force Research Laboratory. The vibration-setup utilizes free boundary conditions by suspending a specimen on its nodal line that when excited, allows for deflection in its first bending mode. The excitation source is an electromagnet coil that attracts and repels a permanent magnet located on the specimen. The experimental specimens, 0.4 mm cold-rolled Ti6Al-4V, are thin specimens representative of geometries that undergo large amounts of cyclic loading during system operations expected for supersonic and hypersonic aerospace technologies. The Free-Free offers an ideal solution to addressing key structural assessment needs for these critical technologies. In the past, the Free-Frees’ usage in the TEFF has resulted in inconsistent experimental setups that lead to increased risk in data repeatability. Diagnosing the known and unknown inconsistencies in the vibration test setup and strategizing solutions to fix the issues are of the utmost concern. Complications in the test setup parameters are artifacts of the uniqueness of the Free-Free test itself. Therefore, a greater understanding of how to achieve reliable and consistent Free-Free fatigue results is crucial for the advancement of aerospace structures and systems.
{"title":"Developing a Consistent Resonance-Induced Fatigue Testing Method on Novel Freely Supported Specimens","authors":"L. Napper","doi":"10.1115/imece2022-95222","DOIUrl":"https://doi.org/10.1115/imece2022-95222","url":null,"abstract":"\u0000 A fatigue test employing vibration-based fatigue known as the “Free-Free” has been in use inside the Turbine Engine Fatigue Facility (TEFF) of the Air Force Research Laboratory. The vibration-setup utilizes free boundary conditions by suspending a specimen on its nodal line that when excited, allows for deflection in its first bending mode. The excitation source is an electromagnet coil that attracts and repels a permanent magnet located on the specimen. The experimental specimens, 0.4 mm cold-rolled Ti6Al-4V, are thin specimens representative of geometries that undergo large amounts of cyclic loading during system operations expected for supersonic and hypersonic aerospace technologies. The Free-Free offers an ideal solution to addressing key structural assessment needs for these critical technologies. In the past, the Free-Frees’ usage in the TEFF has resulted in inconsistent experimental setups that lead to increased risk in data repeatability. Diagnosing the known and unknown inconsistencies in the vibration test setup and strategizing solutions to fix the issues are of the utmost concern. Complications in the test setup parameters are artifacts of the uniqueness of the Free-Free test itself. Therefore, a greater understanding of how to achieve reliable and consistent Free-Free fatigue results is crucial for the advancement of aerospace structures and systems.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"375 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84943838","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}
There are many applications and sectors in today’s era where noise pollution is reaching very high levels. This prolonged noise exposure leads to a detrimental health effect. This may cause loss of concentration, working efficiency, headache, increased blood pressure level, annoyance, and even workplace accidents. Hence, the need to reduce the high noise level is becoming a significant issue. Varieties of absorbing materials are being used in the recent age for noise reduction and sound attenuation. Most of the acoustic enclosures consist of polyurethane foam as a sound absorber. The noise control is achieved by modifying the noise source characteristics, path modification, or muffling at the receiver. The best way to control noise is noise absorption, where acoustic materials are designed to absorb sound. Polyurethane foam is widely accepted because of its good properties like wide absorption frequency range, structural stabilization, low cost, easy handling, and moisture resistance. It has been observed that the sound absorption coefficient (SAC) depends on the thickness of polyurethane foam and the air gap. This paper discusses the different acoustic properties of various acoustic structures consisting of the perforated panel, air gap, and polyurethane foam for the frequency range of 100–4000 Hz. Different combinations of acoustic structures are proposed to observe the effect of absorptivity in terms of sound attenuation. The effect of layer sequence on the acoustic absorption of the structure has been investigated. The relation between the thickness of the material, air gap, and SAC are also analyzed. FEA can accurately analyze the absorption characteristics at normal incidence of sound-absorbing structure. The acoustic structure consisting of polyurethane foam gives the maximum value of SAC for a frequency range of 2300–4000 Hz. The acoustic structure consisting of the perforated panel, air gap, and polyurethane foam give the maximum SAC value for the lower frequency range of 100 to 2300 Hz. In the current study, it has been seen that the acoustic structure consisting of polyurethane foam with an air gap gives the minimum value of SAC. The SAC varies with the air gap and thickness of the foam. The study affirmed that using the perforated panels in acoustic structure gives the maximum value of SAC in the lower frequency range. The SAC of a material is calculated with an analytical method and verified with the experimental method and FEA software. For verification of SAC for different acoustic structures, COMSOL Multiphysics 5.5 results are seen to be in good agreement with a maximum difference of 8.1% with that of the experimental results.
{"title":"Effect of Air Gap, Thickness of Polyurethane (PU) Foam, and Perforated Panel on Sound Absorption Coefficient for Acoustic Structures","authors":"Chetan Patil, Ratnakar R. Ghorpade, R. Askhedkar","doi":"10.1115/imece2022-96880","DOIUrl":"https://doi.org/10.1115/imece2022-96880","url":null,"abstract":"\u0000 There are many applications and sectors in today’s era where noise pollution is reaching very high levels. This prolonged noise exposure leads to a detrimental health effect. This may cause loss of concentration, working efficiency, headache, increased blood pressure level, annoyance, and even workplace accidents. Hence, the need to reduce the high noise level is becoming a significant issue. Varieties of absorbing materials are being used in the recent age for noise reduction and sound attenuation. Most of the acoustic enclosures consist of polyurethane foam as a sound absorber. The noise control is achieved by modifying the noise source characteristics, path modification, or muffling at the receiver. The best way to control noise is noise absorption, where acoustic materials are designed to absorb sound. Polyurethane foam is widely accepted because of its good properties like wide absorption frequency range, structural stabilization, low cost, easy handling, and moisture resistance. It has been observed that the sound absorption coefficient (SAC) depends on the thickness of polyurethane foam and the air gap.\u0000 This paper discusses the different acoustic properties of various acoustic structures consisting of the perforated panel, air gap, and polyurethane foam for the frequency range of 100–4000 Hz. Different combinations of acoustic structures are proposed to observe the effect of absorptivity in terms of sound attenuation. The effect of layer sequence on the acoustic absorption of the structure has been investigated. The relation between the thickness of the material, air gap, and SAC are also analyzed. FEA can accurately analyze the absorption characteristics at normal incidence of sound-absorbing structure. The acoustic structure consisting of polyurethane foam gives the maximum value of SAC for a frequency range of 2300–4000 Hz. The acoustic structure consisting of the perforated panel, air gap, and polyurethane foam give the maximum SAC value for the lower frequency range of 100 to 2300 Hz.\u0000 In the current study, it has been seen that the acoustic structure consisting of polyurethane foam with an air gap gives the minimum value of SAC. The SAC varies with the air gap and thickness of the foam. The study affirmed that using the perforated panels in acoustic structure gives the maximum value of SAC in the lower frequency range. The SAC of a material is calculated with an analytical method and verified with the experimental method and FEA software. For verification of SAC for different acoustic structures, COMSOL Multiphysics 5.5 results are seen to be in good agreement with a maximum difference of 8.1% with that of the experimental results.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90871872","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 stress state of engineering structures is the key information for the reliability evaluation. However, conventional ultrasonic method is not suitable for local stress measurement. The dispersion characteristics of Lamb wave acoustoelasticity show that higher-order Lamb waves near cut-off frequency possess higher sensitivity to stress. Considering that the proximity of zero-group-velocity (ZGV) mode and the cut-off frequency and its sensitivity to local material property, a local stress measurement method based on ZGV mode is proposed for thin plates. An oblique incident ultrasonic system was built for experimental validation. The wedges were tailored made based on the Snell’s law to efficiently excite and receive the signal of S1-ZGV mode. The frequency of S1-ZGV was obtained by spectra analysis after filtering out the direct wave part. Tensile experiments were carried out on a uniform 6061 aluminum plate with 3mm to obtain the calibration curve between S1-ZGV frequency and stress level. Then a step-wise plate was designed to generate different stress at two positions on a tensile testing machine. The stresses were then evaluated by the calibrated frequency-stress coefficient. The measured stresses agreed well with the calculated stress, proving that S1-ZGV method is effective for local stress measurement in thin plates.
{"title":"Experimental Study on Stress Measurement Based on Zero-Group-Velocity (ZGV) Lamb Waves","authors":"He Pancong, Yuan Maodan, Ji Xuanrong, Xu Weiming","doi":"10.1115/imece2022-95409","DOIUrl":"https://doi.org/10.1115/imece2022-95409","url":null,"abstract":"\u0000 The stress state of engineering structures is the key information for the reliability evaluation. However, conventional ultrasonic method is not suitable for local stress measurement. The dispersion characteristics of Lamb wave acoustoelasticity show that higher-order Lamb waves near cut-off frequency possess higher sensitivity to stress. Considering that the proximity of zero-group-velocity (ZGV) mode and the cut-off frequency and its sensitivity to local material property, a local stress measurement method based on ZGV mode is proposed for thin plates. An oblique incident ultrasonic system was built for experimental validation. The wedges were tailored made based on the Snell’s law to efficiently excite and receive the signal of S1-ZGV mode. The frequency of S1-ZGV was obtained by spectra analysis after filtering out the direct wave part. Tensile experiments were carried out on a uniform 6061 aluminum plate with 3mm to obtain the calibration curve between S1-ZGV frequency and stress level. Then a step-wise plate was designed to generate different stress at two positions on a tensile testing machine. The stresses were then evaluated by the calibrated frequency-stress coefficient. The measured stresses agreed well with the calculated stress, proving that S1-ZGV method is effective for local stress measurement in thin plates.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88907415","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}
Utku Güngör, A. Kurt, Mert Lale, Furkan Acar, R. M. Görgülüarslan, H. Ö. Ünver
Meta-materials are artificial materials that perform superior properties in addition to natural behavior. Regardless of their chemical properties, metamaterials show high performance due to their geometric orientation. There are mechanical metamaterials that are used in vibration and acoustic fields, the main subject of which is wave transmission. The propagation of mechanical waves, which can cause problems such as structural damage, fatigue, poor performance, and discomfort in the industry, can be prevented or reduced by using meta-materials. Mechanical waves of various frequencies can be reduced or eliminated by locally resonant metamaterials obtained by adding various masses to viscoelastic materials. Metamaterials can be designed by modifying various lattice structures. Higher performance metamaterials are designed in this study by modifying the lattice structures used in the literature for vibration isolation. Finite element analyzes are carried out to show the transmissibility performance of the designed meta-lattice structures.
{"title":"Design and Numerical Analysis of Locally-Resonant Meta-Lattice Structure for Vibration Attenuation","authors":"Utku Güngör, A. Kurt, Mert Lale, Furkan Acar, R. M. Görgülüarslan, H. Ö. Ünver","doi":"10.1115/imece2022-95206","DOIUrl":"https://doi.org/10.1115/imece2022-95206","url":null,"abstract":"\u0000 Meta-materials are artificial materials that perform superior properties in addition to natural behavior. Regardless of their chemical properties, metamaterials show high performance due to their geometric orientation. There are mechanical metamaterials that are used in vibration and acoustic fields, the main subject of which is wave transmission. The propagation of mechanical waves, which can cause problems such as structural damage, fatigue, poor performance, and discomfort in the industry, can be prevented or reduced by using meta-materials. Mechanical waves of various frequencies can be reduced or eliminated by locally resonant metamaterials obtained by adding various masses to viscoelastic materials. Metamaterials can be designed by modifying various lattice structures. Higher performance metamaterials are designed in this study by modifying the lattice structures used in the literature for vibration isolation. Finite element analyzes are carried out to show the transmissibility performance of the designed meta-lattice structures.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73492506","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}
Matthew Cunha, Richard Martel, Philip Chagnon, Benjamin Jackson, James McCusker, Gloria Ma
This paper presents the development of an Autonomous Undersea Vehicle (AUV) that is capable of an acoustically stealth delivery of a payload. The payload is composed of a black box noise maker and the goal of this “stealth mission” is to minimize the amplitude of the acoustic signal emitting from the noise maker. Various approaches are utilized to reduce the transmission of sound produced by the payload. The design incorporates a vacuum chamber to minimize the noise transmitted through air molecules surrounding the noise maker by removing the air. In addition to a vacuum chamber, both active and passive vibration damping techniques are considered as viable methods of vibration damping, further reducing the sound output. The applied passive damping system has the advantage of using simple mechanical devices, which provides significant advantages in the application to an undersea vehicle with power and space constraints. To complete the mission, a vacuum chamber with a passive vibration damping system was developed and tested by sending the payload through a sound measuring choke point which validated the efficiency of the proposed design.
{"title":"Electro-Mechanical Design of a Vacuum Chamber With Vibration and Noise Damping Capabilities on an Autonomous Undersea Vehicle","authors":"Matthew Cunha, Richard Martel, Philip Chagnon, Benjamin Jackson, James McCusker, Gloria Ma","doi":"10.1115/imece2022-96018","DOIUrl":"https://doi.org/10.1115/imece2022-96018","url":null,"abstract":"\u0000 This paper presents the development of an Autonomous Undersea Vehicle (AUV) that is capable of an acoustically stealth delivery of a payload. The payload is composed of a black box noise maker and the goal of this “stealth mission” is to minimize the amplitude of the acoustic signal emitting from the noise maker.\u0000 Various approaches are utilized to reduce the transmission of sound produced by the payload. The design incorporates a vacuum chamber to minimize the noise transmitted through air molecules surrounding the noise maker by removing the air. In addition to a vacuum chamber, both active and passive vibration damping techniques are considered as viable methods of vibration damping, further reducing the sound output. The applied passive damping system has the advantage of using simple mechanical devices, which provides significant advantages in the application to an undersea vehicle with power and space constraints. To complete the mission, a vacuum chamber with a passive vibration damping system was developed and tested by sending the payload through a sound measuring choke point which validated the efficiency of the proposed design.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"71 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86080417","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}
J. Karlberg, A. Milo, Finnur Pind, Runar Unnthorsson
Human echolocation is a method mainly used within the blind community to navigate using sound emission and analysing the returning echoes from the surrounding environment. Echolocation is predominantly trained by orientation and mobility instructors at visual rehabilitation centres. However, systematic guidelines or protocols focusing on the requirements of room acoustic simulations to accurately represent the auditory cues necessary in a virtual training environment for echolocation have not yet been developed. This paper sets out to investigate the use of geometrical acoustic (GA) calculations for a virtual echolocation training system comparing the measurements from the Benchmark for Room Acoustical Simulation (BRAS) dataset with other GA calculations outcomes. Three simple and one complex test scenes are chosen from the dataset. The calculation settings are optimised for each test scene considering the complexity of the scene, room volume and acoustic phenomena. The monaural room impulse responses from the simulations are analysed with respect to the timing of the reflections and the level relations between the reflections and the resulting frequency response for each scene. These are subsequently compared with each measured counterpart. The paper discusses the results, their limitations, and provides recommendations on the use of GA calculation tools for echolocation training scopes.
{"title":"Preserving Auditory Cues for Human Echolocation Training: A Geometrical Acoustics Study Using a Benchmark Dataset (BRAS)","authors":"J. Karlberg, A. Milo, Finnur Pind, Runar Unnthorsson","doi":"10.1115/imece2022-97044","DOIUrl":"https://doi.org/10.1115/imece2022-97044","url":null,"abstract":"\u0000 Human echolocation is a method mainly used within the blind community to navigate using sound emission and analysing the returning echoes from the surrounding environment. Echolocation is predominantly trained by orientation and mobility instructors at visual rehabilitation centres. However, systematic guidelines or protocols focusing on the requirements of room acoustic simulations to accurately represent the auditory cues necessary in a virtual training environment for echolocation have not yet been developed.\u0000 This paper sets out to investigate the use of geometrical acoustic (GA) calculations for a virtual echolocation training system comparing the measurements from the Benchmark for Room Acoustical Simulation (BRAS) dataset with other GA calculations outcomes. Three simple and one complex test scenes are chosen from the dataset. The calculation settings are optimised for each test scene considering the complexity of the scene, room volume and acoustic phenomena.\u0000 The monaural room impulse responses from the simulations are analysed with respect to the timing of the reflections and the level relations between the reflections and the resulting frequency response for each scene. These are subsequently compared with each measured counterpart. The paper discusses the results, their limitations, and provides recommendations on the use of GA calculation tools for echolocation training scopes.","PeriodicalId":23648,"journal":{"name":"Volume 1: Acoustics, Vibration, and Phononics","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84146865","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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