Yukun Li, Longsheng Wang, S. Zhao, Jinglong Chang, Keren Shen, Shanyao Wang, Xiaojian Cao, Yixuan Wang
Excessive residual stress of the girth weld in pipes will directly damage the pipe strength during its operation. Accurate measurement and effective reduction of the residual stress can ensure the safety of natural gas pipes during their service. In this paper, an X80-type large-diameter natural gas pipe section with girth welds is taken as the research object. The coercive force method is used to characterize the residual stress of the girth weld and its surroundings, and then the distribution law of the residual stress of the girth weld and its surroundings is obtained based on the measurement results of the Blind-hole method; the ultrasonic impact method was used to reduce the girth weld residual stress, and the effect of the ultrasonic impact method on the residual stress reduction was studied by comparing changes of the distribution characteristics of the coercive force in the girth weld and its surroundings before and after the residual stress reduction in the natural gas pipes. Lastly, the in-situ test specimen is made to carry out the uniaxial tensile test so as to study the effect of the ultrasonic impact method on the tensile mechanical properties of pipe welds. This study clarifies the influence law of the ultrasonic impact on the mechanical properties of weld toe materials, and provided technical theoretical guidance for the reduction of field residual stress in natural gas pipes.
{"title":"Research on reduction of residual stress in girth welds of large-diameter natural gas pipes by ultrasonic","authors":"Yukun Li, Longsheng Wang, S. Zhao, Jinglong Chang, Keren Shen, Shanyao Wang, Xiaojian Cao, Yixuan Wang","doi":"10.1093/jom/ufac038","DOIUrl":"https://doi.org/10.1093/jom/ufac038","url":null,"abstract":"Excessive residual stress of the girth weld in pipes will directly damage the pipe strength during its operation. Accurate measurement and effective reduction of the residual stress can ensure the safety of natural gas pipes during their service. In this paper, an X80-type large-diameter natural gas pipe section with girth welds is taken as the research object. The coercive force method is used to characterize the residual stress of the girth weld and its surroundings, and then the distribution law of the residual stress of the girth weld and its surroundings is obtained based on the measurement results of the Blind-hole method; the ultrasonic impact method was used to reduce the girth weld residual stress, and the effect of the ultrasonic impact method on the residual stress reduction was studied by comparing changes of the distribution characteristics of the coercive force in the girth weld and its surroundings before and after the residual stress reduction in the natural gas pipes. Lastly, the in-situ test specimen is made to carry out the uniaxial tensile test so as to study the effect of the ultrasonic impact method on the tensile mechanical properties of pipe welds. This study clarifies the influence law of the ultrasonic impact on the mechanical properties of weld toe materials, and provided technical theoretical guidance for the reduction of field residual stress in natural gas pipes.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61541371","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}
Wire bonding is a key integrated circuit (IC) interconnect technology, and it adheres metal wires to the IC pad and substrate by applying significant compression and energic loading. On the other hand, the Cu/low-k technology of the advanced IC industry is driven by the market demands of small size, and low resistance-capacitance delay applications. Because material properties of Cu/low-k back end of line (BEOL) exhibit significant differences from the conventional Al-based system, 3 new reliability failure modes are introduced after the wire bonding process, including the Al pad lift, Cu pad lift and the nanoscaled Cu diffusion barrier crack. To study the mechanical characteristics of the Cu/low-k BEOL under the wire bonding process loading, this research establishes a set of transient numerical models with mesh control and computation acceleration techniques. The mechanical characteristics of the wire bonding process and the differences between the conventional and Cu/low-k BEOLs are analyzed via the detailed analysis of the historical stress plots over the wire bonding process time. Moreover, the risks of wire bonding induced the failure modes against different Cu/low-k designs are studied by the proper mechanical indices, and optimized design trends are suggested.
{"title":"Investigation of the mechanical characteristics of the Cu/low-k BEOL under wire bonding process loading","authors":"Cadmus C A Yuan, H. M. Chang, K. Chiang","doi":"10.1093/jom/ufac044","DOIUrl":"https://doi.org/10.1093/jom/ufac044","url":null,"abstract":"Wire bonding is a key integrated circuit (IC) interconnect technology, and it adheres metal wires to the IC pad and substrate by applying significant compression and energic loading. On the other hand, the Cu/low-k technology of the advanced IC industry is driven by the market demands of small size, and low resistance-capacitance delay applications. Because material properties of Cu/low-k back end of line (BEOL) exhibit significant differences from the conventional Al-based system, 3 new reliability failure modes are introduced after the wire bonding process, including the Al pad lift, Cu pad lift and the nanoscaled Cu diffusion barrier crack. To study the mechanical characteristics of the Cu/low-k BEOL under the wire bonding process loading, this research establishes a set of transient numerical models with mesh control and computation acceleration techniques. The mechanical characteristics of the wire bonding process and the differences between the conventional and Cu/low-k BEOLs are analyzed via the detailed analysis of the historical stress plots over the wire bonding process time. Moreover, the risks of wire bonding induced the failure modes against different Cu/low-k designs are studied by the proper mechanical indices, and optimized design trends are suggested.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61541462","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}
This paper presents a theoretical analysis of steady-state creeping flow in a composite porous domain with coupling heat transfer. The problem arises in thermal cloaking studies in which it is desirable to hide an obstacle from the surrounding hydrodynamic and thermal fields, by suitably covering the obstacle with a cloak having specific material properties. The particular system under investigation consists of a porous composite region, with a thermal-hydro field driven by imposed temperature and pressure difference in the surrounding. Both two dimensional circular and three-dimensional axisymmetric spherical annuli are considered. Under the validity of Darcy law for a porous medium, an exact solution satisfying the continuity, momentum and energy equations at any Péclet number is derived. The analytical results have been numerically verified using the commercial code COMSOL.
{"title":"Analytical solution of cloaking in creeping flow inside composite porous media with simultaneous heat transfer","authors":"W. Yeung, Fu-Sui Hung, V. Mai, Ruey-Jen Yang","doi":"10.1093/jom/ufac029","DOIUrl":"https://doi.org/10.1093/jom/ufac029","url":null,"abstract":"This paper presents a theoretical analysis of steady-state creeping flow in a composite porous domain with coupling heat transfer. The problem arises in thermal cloaking studies in which it is desirable to hide an obstacle from the surrounding hydrodynamic and thermal fields, by suitably covering the obstacle with a cloak having specific material properties. The particular system under investigation consists of a porous composite region, with a thermal-hydro field driven by imposed temperature and pressure difference in the surrounding. Both two dimensional circular and three-dimensional axisymmetric spherical annuli are considered. Under the validity of Darcy law for a porous medium, an exact solution satisfying the continuity, momentum and energy equations at any Péclet number is derived. The analytical results have been numerically verified using the commercial code COMSOL.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61540569","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}
The subject of seismic metamaterials, inspired from novel ideas in optics and acoustics, has attracted great attention in the last decade for potential applications in earthquake engineering. Simple structure systems, like beams and plates, with periodically attached mechanical resonators provide a simple physical model to interpret the existence of certain frequency bandgap in dispersion relations and to simulate the mechanism of flexural energy attenuation. In this work, we consider simple structure systems of beams and plates with periodically attached resonators. The resonator is composed of a spring, a damper and a mass attached along the beam direction. We utilize the Timoshenko beam model and the Mindlin plate theory to incorporate the shear effect. The plane wave expansion method together with the Bloch theorem is used to expand the governing field into an eigenvalue problem of an infinite complex system, allowing us to characterize the band structures of the dispersion relations. Local resonance and Bragg bandgaps are identified and examined. The effect of thickness ratios, the damping ratio and the shear modulus are exemplified to demonstrate how these factors will affect the formation of bandgaps. This formulation demonstrates a feasibility that a periodic array of mechanical resonators together with suitable material and geometric parameters of beams and plates can be designed to tune with the dispersion behavior in the control of flexure waves. This study may open up new potential in the control of wave propagation in complex continuum systems through the interaction of adequately designed resonators.
{"title":"Bandgaps for flexural waves in infinite beams and plates with a periodic array of resonators","authors":"Jing-Heng Chen, I-Chein Chao, Tungyang Chen","doi":"10.1093/jom/ufac033","DOIUrl":"https://doi.org/10.1093/jom/ufac033","url":null,"abstract":"The subject of seismic metamaterials, inspired from novel ideas in optics and acoustics, has attracted great attention in the last decade for potential applications in earthquake engineering. Simple structure systems, like beams and plates, with periodically attached mechanical resonators provide a simple physical model to interpret the existence of certain frequency bandgap in dispersion relations and to simulate the mechanism of flexural energy attenuation. In this work, we consider simple structure systems of beams and plates with periodically attached resonators. The resonator is composed of a spring, a damper and a mass attached along the beam direction. We utilize the Timoshenko beam model and the Mindlin plate theory to incorporate the shear effect. The plane wave expansion method together with the Bloch theorem is used to expand the governing field into an eigenvalue problem of an infinite complex system, allowing us to characterize the band structures of the dispersion relations. Local resonance and Bragg bandgaps are identified and examined. The effect of thickness ratios, the damping ratio and the shear modulus are exemplified to demonstrate how these factors will affect the formation of bandgaps. This formulation demonstrates a feasibility that a periodic array of mechanical resonators together with suitable material and geometric parameters of beams and plates can be designed to tune with the dispersion behavior in the control of flexure waves. This study may open up new potential in the control of wave propagation in complex continuum systems through the interaction of adequately designed resonators.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61541315","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}
The Stroh formalism is a complex variable formulation developed originally for solving the problems of two-dimensional linear anisotropic elasticity. By separation of the third variable for the linear variation of displacements along the thickness direction, it was proved to be applicable for the problems with coupled stretching-bending deformation. By the Radon transform which maps a three-dimensional solid to a two-dimensional plane, it can be applied to the three-dimensional deformation. By the elastic-viscoelastic correspondence principle, it is also valid for the viscoelastic materials in the Laplace domain. By expansion of the matrix dimension, it can be generalized to the coupled-field materials such as piezoelectric, piezomagnetic and magneto-electro-elastic materials. By introducing a small perturbation on the material constants, it can also be applied to the degenerate materials such as isotropic materials. Thus, in this paper, the Stroh formalism for several different types of materials (anisotropic elastic, piezoelectric, piezomagnetic, magneto-electro-elastic, viscoelastic) and deformations (two-dimensional, coupled stretching-bending, three-dimensional) are organized together and presented in the same mathematical form.
{"title":"Stroh formalism for various types of materials and deformations","authors":"C. Hwu, W. Becker","doi":"10.1093/jom/ufac031","DOIUrl":"https://doi.org/10.1093/jom/ufac031","url":null,"abstract":"The Stroh formalism is a complex variable formulation developed originally for solving the problems of two-dimensional linear anisotropic elasticity. By separation of the third variable for the linear variation of displacements along the thickness direction, it was proved to be applicable for the problems with coupled stretching-bending deformation. By the Radon transform which maps a three-dimensional solid to a two-dimensional plane, it can be applied to the three-dimensional deformation. By the elastic-viscoelastic correspondence principle, it is also valid for the viscoelastic materials in the Laplace domain. By expansion of the matrix dimension, it can be generalized to the coupled-field materials such as piezoelectric, piezomagnetic and magneto-electro-elastic materials. By introducing a small perturbation on the material constants, it can also be applied to the degenerate materials such as isotropic materials. Thus, in this paper, the Stroh formalism for several different types of materials (anisotropic elastic, piezoelectric, piezomagnetic, magneto-electro-elastic, viscoelastic) and deformations (two-dimensional, coupled stretching-bending, three-dimensional) are organized together and presented in the same mathematical form.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61540715","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}
S. Hsiau, K. Hutter, Li-Shin Lu, Andreas Teufel, S. Chou, L. Sheng
Experiments were performed in an Couette ring shear cell with particles from the food industry of nearly spherical geometry and nominal diameters between 2.0 and 6.7 mm and with quartz grains with 2.1 to 3.3 mm diameter to examine whether rapid shear flow would give rise to an appreciable change in the granular properties. In particular, it was suspected that surface roughness would change during shearing and lead to changes in the values of the internal and wall friction angles. Measuring these angles corroborated the supposition that abrasion of the particles reduced their frictional resistance, both via the internal and wall friction angles. This demonstrates that roughness changes may occur in granular flows and should in those situations not be ignored in the theoretical descriptions.
{"title":"Discovery and study of abrasion behavior in granular shear flow","authors":"S. Hsiau, K. Hutter, Li-Shin Lu, Andreas Teufel, S. Chou, L. Sheng","doi":"10.1093/jom/ufac032","DOIUrl":"https://doi.org/10.1093/jom/ufac032","url":null,"abstract":"Experiments were performed in an Couette ring shear cell with particles from the food industry of nearly spherical geometry and nominal diameters between 2.0 and 6.7 mm and with quartz grains with 2.1 to 3.3 mm diameter to examine whether rapid shear flow would give rise to an appreciable change in the granular properties. In particular, it was suspected that surface roughness would change during shearing and lead to changes in the values of the internal and wall friction angles. Measuring these angles corroborated the supposition that abrasion of the particles reduced their frictional resistance, both via the internal and wall friction angles. This demonstrates that roughness changes may occur in granular flows and should in those situations not be ignored in the theoretical descriptions.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61540752","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}
In contrast to building structures, little attention has been paid to the seismic performance of non-structures in buildings, especially of eccentric non-structures. This paper attempts to explore the rocking and overturning of eccentric blocks, which could be the equipment or non-structural components in buildings, subjected to horizontal vibration. In the present study, a non-structure is regarded as a rigid block with tunable mass eccentricity, and the contact friction is assumed to be large enough to prevent the rigid block from sliding. A free shaking test is first carried out to determine the value of the coefficient of restitution. Force oscillations are then investigated to determine the critical time and acceleration when the eccentric blocks fall down under the swept-frequency oscillation. Finally, an actual acceleration from the seismic records is executed on each of the eccentric blocks to measure and to explore the corresponding toppling probability. It is found that the toppling of blocks is not necessarily linked to the magnitude of the peak ground acceleration.
{"title":"On the response of eccentric non-structures subjected to horizontal oscillation","authors":"Liang-Shen Su, Chi-Hao Lin, Kuo-Ching Chen","doi":"10.1093/jom/ufac040","DOIUrl":"https://doi.org/10.1093/jom/ufac040","url":null,"abstract":"In contrast to building structures, little attention has been paid to the seismic performance of non-structures in buildings, especially of eccentric non-structures. This paper attempts to explore the rocking and overturning of eccentric blocks, which could be the equipment or non-structural components in buildings, subjected to horizontal vibration. In the present study, a non-structure is regarded as a rigid block with tunable mass eccentricity, and the contact friction is assumed to be large enough to prevent the rigid block from sliding. A free shaking test is first carried out to determine the value of the coefficient of restitution. Force oscillations are then investigated to determine the critical time and acceleration when the eccentric blocks fall down under the swept-frequency oscillation. Finally, an actual acceleration from the seismic records is executed on each of the eccentric blocks to measure and to explore the corresponding toppling probability. It is found that the toppling of blocks is not necessarily linked to the magnitude of the peak ground acceleration.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61541513","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}
Chun-Kai Huang, Chia-Jui Hu, I-Chia Chang, Pei-Chun Lin
The development and investigation of a quadruped robot's dynamic bounding and pronking gaits using a sagittal planar model that captures the robot's natural dynamics are presented. The proposed reduced-order model, termed the Two-rolling-leg (TRL) model, is a 3-DOF planar rigid-body model consisting of two half-circular compliant legs with pure rolling contact. Throughout the non-dimensional steps-to-fall and fixed-point analysis, the model with feasible intrinsic parameters can passively perform the periodic dynamic behavior of bounding and pronking, revealing a relationship between the body parameters and the preferred dynamic behaviors. Dynamic bounding and pronking on a quadruped robot were initiated by developing a model-based control strategy based on the searched periodic dynamic behaviors of the TRL model. The experimental results showed that the robot can initiate its dynamic bounding and pronking behaviors at various forward speeds merely by causing the motor to track a preset trajectory derived from the fixed-point motion of the TRL model using position control. The higher success rate of the robot in stable bounding than in pronking is in line with the results from the analysis of the model. This paper confirms that the dynamic multi-gait locomotion of a quadrupedal robot can be initiated by utilizing a reduced-order model for control guidance and that the body configuration plays an important role in determining the characteristics of the dynamic behaviors.
{"title":"A passive planar model with rolling contact and its application for bounding and pronking on a quadruped robot","authors":"Chun-Kai Huang, Chia-Jui Hu, I-Chia Chang, Pei-Chun Lin","doi":"10.1093/jom/ufac046","DOIUrl":"https://doi.org/10.1093/jom/ufac046","url":null,"abstract":"The development and investigation of a quadruped robot's dynamic bounding and pronking gaits using a sagittal planar model that captures the robot's natural dynamics are presented. The proposed reduced-order model, termed the Two-rolling-leg (TRL) model, is a 3-DOF planar rigid-body model consisting of two half-circular compliant legs with pure rolling contact. Throughout the non-dimensional steps-to-fall and fixed-point analysis, the model with feasible intrinsic parameters can passively perform the periodic dynamic behavior of bounding and pronking, revealing a relationship between the body parameters and the preferred dynamic behaviors. Dynamic bounding and pronking on a quadruped robot were initiated by developing a model-based control strategy based on the searched periodic dynamic behaviors of the TRL model. The experimental results showed that the robot can initiate its dynamic bounding and pronking behaviors at various forward speeds merely by causing the motor to track a preset trajectory derived from the fixed-point motion of the TRL model using position control. The higher success rate of the robot in stable bounding than in pronking is in line with the results from the analysis of the model. This paper confirms that the dynamic multi-gait locomotion of a quadrupedal robot can be initiated by utilizing a reduced-order model for control guidance and that the body configuration plays an important role in determining the characteristics of the dynamic behaviors.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61542028","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}
Free vibration of a single-walled carbon nanotube (SWCNT) embedded in an elastic medium is studied on the basis of the nonlocal Timoshenko beam model. Influences of the slenderness ratios, the boundary conditions, the atomic structures and the stiffness of the embedded medium on the natural frequencies and mode shapes of SWCNT are examined. The nonlocal effect is significant for the higher modes of SWCNT with a small slenderness ratio embedded in a soft elastic medium, and it softens the SWCNT except for the fundamental frequency of the clamped–free SWCNT.
{"title":"Free vibration of a single-walled carbon nanotube based on the nonlocal Timoshenko beam model","authors":"Yu-Chi Su, TS Cho","doi":"10.1093/jom/ufab028","DOIUrl":"https://doi.org/10.1093/jom/ufab028","url":null,"abstract":"\u0000 Free vibration of a single-walled carbon nanotube (SWCNT) embedded in an elastic medium is studied on the basis of the nonlocal Timoshenko beam model. Influences of the slenderness ratios, the boundary conditions, the atomic structures and the stiffness of the embedded medium on the natural frequencies and mode shapes of SWCNT are examined. The nonlocal effect is significant for the higher modes of SWCNT with a small slenderness ratio embedded in a soft elastic medium, and it softens the SWCNT except for the fundamental frequency of the clamped–free SWCNT.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2021-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43404157","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}
An understanding of the characteristics and mechanisms of structural vibrations produced by underwater vehicles is required to reduce sound radiation in submarine environments. In this study, experiments were performed using a continuously running machine to produce low-frequency vibrations in a submerged, watertight, steel circular cylinder in the centre of a 176 × 8 × 4 m3 towing tank, and the underwater radiation sound field was measured. Finite element method simulations of the system were also performed and showed good agreement with the experimental results. The wall effects of the towing tank were simulated in detail by changing the alternative impedances of the wall. The reflection and acoustic impedance of the towing tank walls were found to significantly affect the underwater sound field in both the experiments and simulations. An analytical solution was used to verify the frequency range applied in the simulation analysis. The results of this study provide a measurement procedure and a simulation method, which can be used to evaluate the underwater radiation sound field from the vehicle machine running in the water at wall boundary environment.
{"title":"On underwater sound radiation in a towing tank induced by continuous machine vibration in a steel circular cylinder","authors":"Wu C, Too G.","doi":"10.1093/jom/ufab026","DOIUrl":"https://doi.org/10.1093/jom/ufab026","url":null,"abstract":"<span><div>Abstract</div>An understanding of the characteristics and mechanisms of structural vibrations produced by underwater vehicles is required to reduce sound radiation in submarine environments. In this study, experiments were performed using a continuously running machine to produce low-frequency vibrations in a submerged, watertight, steel circular cylinder in the centre of a 176 × 8 × 4 m<sup>3</sup> towing tank, and the underwater radiation sound field was measured. Finite element method simulations of the system were also performed and showed good agreement with the experimental results. The wall effects of the towing tank were simulated in detail by changing the alternative impedances of the wall. The reflection and acoustic impedance of the towing tank walls were found to significantly affect the underwater sound field in both the experiments and simulations. An analytical solution was used to verify the frequency range applied in the simulation analysis. The results of this study provide a measurement procedure and a simulation method, which can be used to evaluate the underwater radiation sound field from the vehicle machine running in the water at wall boundary environment.</span>","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2021-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138536398","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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