Yuanran Qiu, Wei Xu, Zechao Hu, Junqiang Fu, Mengxuan He
Vibration induced by marine power devices (MPD) transmitting to the hull structure is one of the most important factors that cause ship vibration and underwater sound radiation. Vibration isolation technologies (VIT) are widely applied to reduce the vibration transmission. However, the overweight issue of VIT for marine power devices is a currently challenging engineering problem. The current reserve of lightweight and high-efficiency VIT for MPD and relevant theoretical and design research are seriously insufficient. This article first elaborates the causes of the overweight problem of VIT for MPD: (1) failing to grasp the quantitative law; (2) single vibration suppression mechanism. Then, it systematically sorts out the technical methods and application examples with potential to solve the overweight problem, such as dynamic optimization design, lightweight material method, novel intermediate mass structures, distributed dynamic vibration absorbers (DDVAs), locally resonant structures (LRS), particle damping (PD), quasizero stiffness isolators (QZSI), and active vibration control (AVC) technologies. Finally, the future development of lightweight VIT for MPD is prospected. It can be used as a reference for marine vessel vibration attenuation research and engineering design.
船用动力装置（MPD）传递到船体结构引起的振动是造成船舶振动和水下声辐射的最重要因素之一。隔振技术（VIT）被广泛应用于减少振动传播。然而，船用动力装置的隔振技术超重问题是目前具有挑战性的工程问题。目前，用于 MPD 的轻质高效 VIT 储备以及相关理论和设计研究严重不足。本文首先阐述了船用动力装置 VIT 超重问题的成因：（1）定量规律把握不准；（2）振动抑制机理单一。然后，系统梳理了动态优化设计、轻量化材料法、新型中间质量结构、分布式动态吸振器（DDVA）、局部共振结构（LRS）、颗粒阻尼（PD）、准零刚度隔振器（QZSI）、主动振动控制（AVC）技术等有可能解决超重问题的技术方法和应用实例。最后，对 MPD 轻质 VIT 的未来发展进行了展望。它可为海洋船舶减振研究和工程设计提供参考。
{"title":"Review of Lightweight Vibration Isolation Technologies for Marine Power Devices","authors":"Yuanran Qiu, Wei Xu, Zechao Hu, Junqiang Fu, Mengxuan He","doi":"10.1155/2024/1076935","DOIUrl":"https://doi.org/10.1155/2024/1076935","url":null,"abstract":"Vibration induced by marine power devices (MPD) transmitting to the hull structure is one of the most important factors that cause ship vibration and underwater sound radiation. Vibration isolation technologies (VIT) are widely applied to reduce the vibration transmission. However, the overweight issue of VIT for marine power devices is a currently challenging engineering problem. The current reserve of lightweight and high-efficiency VIT for MPD and relevant theoretical and design research are seriously insufficient. This article first elaborates the causes of the overweight problem of VIT for MPD: (1) failing to grasp the quantitative law; (2) single vibration suppression mechanism. Then, it systematically sorts out the technical methods and application examples with potential to solve the overweight problem, such as dynamic optimization design, lightweight material method, novel intermediate mass structures, distributed dynamic vibration absorbers (DDVAs), locally resonant structures (LRS), particle damping (PD), quasizero stiffness isolators (QZSI), and active vibration control (AVC) technologies. Finally, the future development of lightweight VIT for MPD is prospected. It can be used as a reference for marine vessel vibration attenuation research and engineering design.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139374214","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}
To address the degradation of diagnostic performance due to data distribution differences and the scarcity of labeled fault data, this study has focused on transfer learning-based cross-domain fault diagnosis, which attracts considerable attention. However, deep transfer learning-based methods often present a challenge due to their time-consuming and costly nature, particularly in tuning hyperparameters. For this issue, on the basis of classical features-based transfer learning method, this study introduces a new framework for bearing fault diagnosis based on supervised joint distribution adaptation and feature refinement. It first utilizes ensemble empirical mode decomposition to process raw signals, and statistical features extraction is implemented. Then, a new feature refinement module is designed to refine domain adaptation features from high-dimensional feature set by evaluating the fault distinguishability and working-condition invariance of feature data. Next, it proposes a supervised joint distribution adaptation method to conduct improved joint distribution alignment that preserves neighborhood relationships within a manifold subspace. Finally, an adaptive classifier is trained to predict fault labels of feature data across varying working conditions. To prove the cross-domain fault diagnosis performance and superiority of the proposed methods, two bearing datasets are applied for experiments, and the experimental results verify that the model built by the proposed framework can achieve desirable diagnosis performance under different working conditions and that it apparently outperforms comparative models.
{"title":"A New Framework Based on Supervised Joint Distribution Adaptation for Bearing Fault Diagnosis across Diverse Working Conditions","authors":"Chengyao Liu, Fei Dong","doi":"10.1155/2024/8296809","DOIUrl":"https://doi.org/10.1155/2024/8296809","url":null,"abstract":"To address the degradation of diagnostic performance due to data distribution differences and the scarcity of labeled fault data, this study has focused on transfer learning-based cross-domain fault diagnosis, which attracts considerable attention. However, deep transfer learning-based methods often present a challenge due to their time-consuming and costly nature, particularly in tuning hyperparameters. For this issue, on the basis of classical features-based transfer learning method, this study introduces a new framework for bearing fault diagnosis based on supervised joint distribution adaptation and feature refinement. It first utilizes ensemble empirical mode decomposition to process raw signals, and statistical features extraction is implemented. Then, a new feature refinement module is designed to refine domain adaptation features from high-dimensional feature set by evaluating the fault distinguishability and working-condition invariance of feature data. Next, it proposes a supervised joint distribution adaptation method to conduct improved joint distribution alignment that preserves neighborhood relationships within a manifold subspace. Finally, an adaptive classifier is trained to predict fault labels of feature data across varying working conditions. To prove the cross-domain fault diagnosis performance and superiority of the proposed methods, two bearing datasets are applied for experiments, and the experimental results verify that the model built by the proposed framework can achieve desirable diagnosis performance under different working conditions and that it apparently outperforms comparative models.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139084746","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}
High accuracy and stability in mechanical transmission are crucial for various applications. In spite of the validity of mechanical enhancements, control algorithms’ fulfilment offers a cost-effective and efficient approach to mitigating the effects of noise signals. This study presents a hybrid algorithm that combines EMD with the least mean square (LMS) error to achieve online denoising. Within the algorithm, consecutive mean square error (CMSE) and the 2-norm metric are employed to assess the similarity between intrinsic mode functions (IMFs) and the original signal; therefore, IMFs are separated into three distinct components: noise components, information components, and mixed components. The denoised signal is obtained by partial reconstruction. Subsequently, the denoised signal is employed as a reference signal in the LMS algorithm, which is utilized for practical processing. The performance evaluation of the developed algorithm employs simulation and experimental signals. The obtained results illustrate that the presented approach achieves sufficient accuracy and stability.
{"title":"A Denoising Algorithm Combined with EMD and LMS for Precise Transmission Signal","authors":"Lei Song, Yongjun Cao, Yushan Zhou, Dongdong You","doi":"10.1155/2023/8853345","DOIUrl":"https://doi.org/10.1155/2023/8853345","url":null,"abstract":"High accuracy and stability in mechanical transmission are crucial for various applications. In spite of the validity of mechanical enhancements, control algorithms’ fulfilment offers a cost-effective and efficient approach to mitigating the effects of noise signals. This study presents a hybrid algorithm that combines EMD with the least mean square (LMS) error to achieve online denoising. Within the algorithm, consecutive mean square error (CMSE) and the <svg height=\"8.8423pt\" style=\"vertical-align:-0.2064009pt\" version=\"1.1\" viewbox=\"-0.0498162 -8.6359 6.16729 8.8423\" width=\"6.16729pt\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g transform=\"matrix(.013,0,0,-0.013,0,0)\"></path></g></svg>2-norm metric are employed to assess the similarity between intrinsic mode functions (IMFs) and the original signal; therefore, IMFs are separated into three distinct components: noise components, information components, and mixed components. The denoised signal is obtained by partial reconstruction. Subsequently, the denoised signal is employed as a reference signal in the LMS algorithm, which is utilized for practical processing. The performance evaluation of the developed algorithm employs simulation and experimental signals. The obtained results illustrate that the presented approach achieves sufficient accuracy and stability.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139066252","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}
María Teresa Tejedor Sastre, Alexandre Leblanc, Antoine Lavie, Christian Vanhille
This paper presents the development of a numerical model able to track in time the behavior of nonlinear focused ultrasound when interacting with tiny gas bubbles in a liquid. Our goal here is to analyze the frequency components of the waves by developing a model that can easily be adapted to the geometrical restrictions and complexities that come out in several application frameworks (sonochemistry, medicine, and engineering). We thus model the behavior of nonlinear focused ultrasound propagating in a liquid with gas bubbles by means of the finite-element method in an axisymmetric three-dimensional domain and the generalized- method in the time domain. The model solves a differential system derived for the nonlinear interaction of acoustic waves and gas bubble oscillations. The high nonlinearity and dispersion of the bubbly medium hugely affect the behavior of the finite-amplitude waves. These characteristics are used here to generate frequency components of the signals that do not exist at the source through nonlinear mixing (parametric antenna). The ability of the model to work with complex geometries, which is the main advantage of the method, is illustrated through the simulation of nonlinear focused ultrasound in a medium excited from two spherical sources in opposite directions.
{"title":"Modeling and Simulation of Parametric Nonlinear Focused Ultrasound in Three-Dimensional Bubbly Liquids with Axial Symmetry by a Finite-Element Model","authors":"María Teresa Tejedor Sastre, Alexandre Leblanc, Antoine Lavie, Christian Vanhille","doi":"10.1155/2023/1777961","DOIUrl":"https://doi.org/10.1155/2023/1777961","url":null,"abstract":"This paper presents the development of a numerical model able to track in time the behavior of nonlinear focused ultrasound when interacting with tiny gas bubbles in a liquid. Our goal here is to analyze the frequency components of the waves by developing a model that can easily be adapted to the geometrical restrictions and complexities that come out in several application frameworks (sonochemistry, medicine, and engineering). We thus model the behavior of nonlinear focused ultrasound propagating in a liquid with gas bubbles by means of the finite-element method in an axisymmetric three-dimensional domain and the generalized-<svg height=\"6.1673pt\" style=\"vertical-align:-0.2063904pt\" version=\"1.1\" viewbox=\"-0.0498162 -5.96091 7.51131 6.1673\" width=\"7.51131pt\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g transform=\"matrix(.013,0,0,-0.013,0,0)\"></path></g></svg> method in the time domain. The model solves a differential system derived for the nonlinear interaction of acoustic waves and gas bubble oscillations. The high nonlinearity and dispersion of the bubbly medium hugely affect the behavior of the finite-amplitude waves. These characteristics are used here to generate frequency components of the signals that do not exist at the source through nonlinear mixing (parametric antenna). The ability of the model to work with complex geometries, which is the main advantage of the method, is illustrated through the simulation of nonlinear focused ultrasound in a medium excited from two spherical sources in opposite directions.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139066362","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}
Jie Zhang, Shoushi Gao, Yifeng He, Tao Yang, Tong Li, Yihui Yan, Jianping Sun
This study addresses the issue of large deformation in soft rock roadways, using the 50213 tailgate of Guantun Coal Mine as a case study. Field investigations were conducted to assess the condition of roadway bolts, anchor cables, and the internal damage characteristics of the surrounding rock. The upper bound method of limit analysis in plastic mechanics was utilized to construct a failure model for the surrounding rock and derive the upper limit solution of roof failure by integrating the principle of virtual work and variational extremum theorem. Physical similarity simulations were employed to investigate the fracture distribution and evolution law of the surrounding rock. Based on the deformation and instability mechanism of the roadway, optimized support parameters for soft rock roadways were proposed and verified through numerical simulation. The results indicate that the surrounding rock of the sharp corner of the roadway is initially destroyed and develops upward with increasing stress. The interconnected horizontal separation cracks at the anchorage end of the anchor cable and shear fracture zones at the two corners ultimately lead to the overall instability of the anchorage arch. Furthermore, the theoretical calculation boundary exhibited significant similarity with the failure evolution law and distribution pattern. Following the adoption of the optimized support scheme, roof subsidence decreased by 46.7% compared to the original scheme, and the amount of movement on both sides decreased by 36.2%. The control effect of the surrounding rock was favorable, and its internal stability was significantly improved, thereby effectively resolving the issue of large deformation in soft rock roadways.
{"title":"Study on the Upper Limit of Roof Failure in Soft Rock Roadway","authors":"Jie Zhang, Shoushi Gao, Yifeng He, Tao Yang, Tong Li, Yihui Yan, Jianping Sun","doi":"10.1155/2023/3837106","DOIUrl":"https://doi.org/10.1155/2023/3837106","url":null,"abstract":"This study addresses the issue of large deformation in soft rock roadways, using the 50213 tailgate of Guantun Coal Mine as a case study. Field investigations were conducted to assess the condition of roadway bolts, anchor cables, and the internal damage characteristics of the surrounding rock. The upper bound method of limit analysis in plastic mechanics was utilized to construct a failure model for the surrounding rock and derive the upper limit solution of roof failure by integrating the principle of virtual work and variational extremum theorem. Physical similarity simulations were employed to investigate the fracture distribution and evolution law of the surrounding rock. Based on the deformation and instability mechanism of the roadway, optimized support parameters for soft rock roadways were proposed and verified through numerical simulation. The results indicate that the surrounding rock of the sharp corner of the roadway is initially destroyed and develops upward with increasing stress. The interconnected horizontal separation cracks at the anchorage end of the anchor cable and shear fracture zones at the two corners ultimately lead to the overall instability of the anchorage arch. Furthermore, the theoretical calculation boundary exhibited significant similarity with the failure evolution law and distribution pattern. Following the adoption of the optimized support scheme, roof subsidence decreased by 46.7% compared to the original scheme, and the amount of movement on both sides decreased by 36.2%. The control effect of the surrounding rock was favorable, and its internal stability was significantly improved, thereby effectively resolving the issue of large deformation in soft rock roadways.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139056515","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}
Liangting Wang, Zhishan Zheng, Zheng Xiahou, Xijian Chao, Ming Xia
In order to study the dynamic mechanical properties of concrete under freeze-thaw cycles, uniaxial impact compression tests were conducted on concrete specimens with different number of freeze-thaw cycles (0, 25, 50, 75, and 100) using a 50 mm diameter split Hopkinson pressure bar (SHPB) test device at an impact air pressure of 0.4 MPa and combined with a CT scanning system to analyze the internal fissures of concrete specimens before and after freeze-thaw cycles. The results showed the following. (1) The concrete specimens were divided into linear elastic stage, plastic stage, and damage stage under the freeze-thaw cycle, and the macroscopic mechanical parameters of the specimens were weakened with the increase of the number of freeze-thaw cycles. (2) Freeze-thaw intensified the expansion and penetration of the internal fracture of the specimens, and the CT scan results showed that the internal fracture parameters of the concrete specimens were increased with the increase of the number of freeze-thaw cycles, and the structural characteristics of the internal fracture show gradually complex expansion and evolution characteristics. (3) The degree of damage was defined at the fine level, which increased with the number of freeze-thaw cycles, establishing an intrinsic link between the fine deterioration of concrete specimens and the loss of macroscopic parameters under freeze-thaw cycles. The results are of great significance to further elucidate the internal structural characteristics of concrete material damage under freeze-thaw conditions and to reveal the damage deterioration mechanism.
{"title":"Study on the Dynamic Properties of Concrete under Freeze-Thaw Cycles and CT Fine View Damage","authors":"Liangting Wang, Zhishan Zheng, Zheng Xiahou, Xijian Chao, Ming Xia","doi":"10.1155/2023/6357286","DOIUrl":"https://doi.org/10.1155/2023/6357286","url":null,"abstract":"In order to study the dynamic mechanical properties of concrete under freeze-thaw cycles, uniaxial impact compression tests were conducted on concrete specimens with different number of freeze-thaw cycles (0, 25, 50, 75, and 100) using a 50 mm diameter split Hopkinson pressure bar (SHPB) test device at an impact air pressure of 0.4 MPa and combined with a CT scanning system to analyze the internal fissures of concrete specimens before and after freeze-thaw cycles. The results showed the following. (1) The concrete specimens were divided into linear elastic stage, plastic stage, and damage stage under the freeze-thaw cycle, and the macroscopic mechanical parameters of the specimens were weakened with the increase of the number of freeze-thaw cycles. (2) Freeze-thaw intensified the expansion and penetration of the internal fracture of the specimens, and the CT scan results showed that the internal fracture parameters of the concrete specimens were increased with the increase of the number of freeze-thaw cycles, and the structural characteristics of the internal fracture show gradually complex expansion and evolution characteristics. (3) The degree of damage was defined at the fine level, which increased with the number of freeze-thaw cycles, establishing an intrinsic link between the fine deterioration of concrete specimens and the loss of macroscopic parameters under freeze-thaw cycles. The results are of great significance to further elucidate the internal structural characteristics of concrete material damage under freeze-thaw conditions and to reveal the damage deterioration mechanism.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139056828","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}
To cope with the deterioration of vehicle dynamic performance induced by the increased mass and vertical stiffness of selected nonpneumatic wheels (NPWs), this study proposed a new vibration damping system (NVDS) based on the dynamic vibration absorber (DVA). First, a quarter-vehicle model containing the effective vertical stiffness of the NPW is established. Then, the effect of increased wheel mass and stiffness on vehicle dynamic performance is investigated from various aspects. To improve the handling performance of the vehicle with NPWs, a DVA-based NVDS is proposed. The sensitivities of handling performance and ride comfort to parameter changes are investigated to determine the selection range of parameters. The multiobjective genetic algorithm (GA) is employed to determine the optimal parameters of NVDS. The results obtained under different road excitations indicate that the proposed NVDS can significantly enhance the handling performance and ride comfort of the vehicle.
{"title":"Design and Optimization of a New Vibration Damping System for the Driving Characteristics of the Selected Case of Replacing Pneumatic Wheels with Nonpneumatic Wheels","authors":"Renkai Ding, Ping Wang, Ruochen Wang, Dong Sun","doi":"10.1155/2023/6050633","DOIUrl":"https://doi.org/10.1155/2023/6050633","url":null,"abstract":"To cope with the deterioration of vehicle dynamic performance induced by the increased mass and vertical stiffness of selected nonpneumatic wheels (NPWs), this study proposed a new vibration damping system (NVDS) based on the dynamic vibration absorber (DVA). First, a quarter-vehicle model containing the effective vertical stiffness of the NPW is established. Then, the effect of increased wheel mass and stiffness on vehicle dynamic performance is investigated from various aspects. To improve the handling performance of the vehicle with NPWs, a DVA-based NVDS is proposed. The sensitivities of handling performance and ride comfort to parameter changes are investigated to determine the selection range of parameters. The multiobjective genetic algorithm (GA) is employed to determine the optimal parameters of NVDS. The results obtained under different road excitations indicate that the proposed NVDS can significantly enhance the handling performance and ride comfort of the vehicle.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138947057","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}
During the launch process of an electromagnetic railgun, the armature is subjected to the ampere force and moves along the rail with variable acceleration. In this period, the rail is excited by time varying moving loads and generates lateral vibration. For analysis, the rail is simplified as an Euler–Bernoulli beam, and the nonlinear dynamic equation of the beam under time varying moving loads is established. The electromagnetic repulsive force between rails, the contact pressure between the armature and the rail, and the thermal expansion pressure acting on the rail are taken into account. The lateral vibration response of the rail is achieved by using the analytical method combined with numerical integration. The variable motion of the armature during launch is also illustrated. Furthermore, the study of the effects of structure parameters on the vibration amplitude of the rail is performed. The research results can provide a theoretical basis for the structural optimization and vibration reduction of electromagnetic railguns.
{"title":"Dynamic Response and Parameter Analysis of Electromagnetic Railguns under Time Varying Moving Loads","authors":"Lilan Liu, Xukai Zhang, Jiayi Wang","doi":"10.1155/2023/4351878","DOIUrl":"https://doi.org/10.1155/2023/4351878","url":null,"abstract":"During the launch process of an electromagnetic railgun, the armature is subjected to the ampere force and moves along the rail with variable acceleration. In this period, the rail is excited by time varying moving loads and generates lateral vibration. For analysis, the rail is simplified as an Euler–Bernoulli beam, and the nonlinear dynamic equation of the beam under time varying moving loads is established. The electromagnetic repulsive force between rails, the contact pressure between the armature and the rail, and the thermal expansion pressure acting on the rail are taken into account. The lateral vibration response of the rail is achieved by using the analytical method combined with numerical integration. The variable motion of the armature during launch is also illustrated. Furthermore, the study of the effects of structure parameters on the vibration amplitude of the rail is performed. The research results can provide a theoretical basis for the structural optimization and vibration reduction of electromagnetic railguns.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138743183","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}
Daniele Kauctz Monteiro, Letícia Fleck Fadel Miguel, Gustavo Zeni, Tiago Becker, Giovanni Souza de Andrade, Rodrigo Rodrigues de Barros
This paper presents a structural health monitoring method based on artificial neural networks (ANNs) capable of detecting, locating, and quantifying damage in a single stage. The proposed framework employs a supervised neural network model that uses input factors calculated by modal parameters (natural frequencies or mode shapes), and output factors that represent the damage situation of elements or regions in a structural system. Unlike many papers in the literature that test damage detection methods only in numerical examples or simple experimental tests, this work also assesses the presented method in a real structure showing that it has potential for applications in real practical situations. Three different cases are evaluated through the methodology: numerical simulations, an experimental lab structure, and a real bridge. Initially, a cantilever beam and a 10-bar truss were numerically analyzed under ambient vibrations with different damage scenarios and noise levels. Afterward, the method is assessed in an experimental beam structure and in the Z24 bridge benchmark. The numerical simulations showed that the methodology is promising for identifying, locating, and quantifying single and multiple damages in a single stage, even with noise in the acceleration signals and changes in the first vibration mode of 0.015%. In addition, the Z24 bridge study confirmed that the damage detection method can localize damage in real civil structures considering only natural frequencies in the input factors, despite a mean difference of 4.08% between the frequencies in the healthy and damaged conditions.
{"title":"Detection, Localization, and Quantification of Damage in Structures via Artificial Neural Networks","authors":"Daniele Kauctz Monteiro, Letícia Fleck Fadel Miguel, Gustavo Zeni, Tiago Becker, Giovanni Souza de Andrade, Rodrigo Rodrigues de Barros","doi":"10.1155/2023/8829298","DOIUrl":"https://doi.org/10.1155/2023/8829298","url":null,"abstract":"This paper presents a structural health monitoring method based on artificial neural networks (ANNs) capable of detecting, locating, and quantifying damage in a single stage. The proposed framework employs a supervised neural network model that uses input factors calculated by modal parameters (natural frequencies or mode shapes), and output factors that represent the damage situation of elements or regions in a structural system. Unlike many papers in the literature that test damage detection methods only in numerical examples or simple experimental tests, this work also assesses the presented method in a real structure showing that it has potential for applications in real practical situations. Three different cases are evaluated through the methodology: numerical simulations, an experimental lab structure, and a real bridge. Initially, a cantilever beam and a 10-bar truss were numerically analyzed under ambient vibrations with different damage scenarios and noise levels. Afterward, the method is assessed in an experimental beam structure and in the Z24 bridge benchmark. The numerical simulations showed that the methodology is promising for identifying, locating, and quantifying single and multiple damages in a single stage, even with noise in the acceleration signals and changes in the first vibration mode of 0.015%. In addition, the Z24 bridge study confirmed that the damage detection method can localize damage in real civil structures considering only natural frequencies in the input factors, despite a mean difference of 4.08% between the frequencies in the healthy and damaged conditions.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138742588","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 main purpose of this article is to investigate the bursting oscillations of the medical shaking tables resulted from friction in practical application. Using the theoretical method of linear loading, the analytic expression of friction acting on an eccentric turntable is derived in detail. Besides, through numerical simulation, the decisive role of friction in bursting oscillations is verified. On this basis, several practical operation plans are proposed to eliminate harmful vibrations. Last but not least, the effectiveness of theoretical methods is validated through example calculations in cases with special parameters.
{"title":"Bursting Oscillation Mechanisms of a Desktop Medical Shaker with Eccentric Turntables Affected by Dry Friction","authors":"Rui Qu, Xin Xia","doi":"10.1155/2023/8374444","DOIUrl":"https://doi.org/10.1155/2023/8374444","url":null,"abstract":"The main purpose of this article is to investigate the bursting oscillations of the medical shaking tables resulted from friction in practical application. Using the theoretical method of linear loading, the analytic expression of friction acting on an eccentric turntable is derived in detail. Besides, through numerical simulation, the decisive role of friction in bursting oscillations is verified. On this basis, several practical operation plans are proposed to eliminate harmful vibrations. Last but not least, the effectiveness of theoretical methods is validated through example calculations in cases with special parameters.","PeriodicalId":21915,"journal":{"name":"Shock and Vibration","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138580187","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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