Due to the tower cranes usually working in an outdoor environment, it is generally unavoidable for the obstacle to exist in the transportation path. Thus, it is critical for the tower crane systems to guarantee their safety and efficiency simultaneously. In this paper, for the 4DOF tower cranes, a novel adaptive tracking control approach is proposed by considering obstacle-avoidance trajectory planning. The state constraint equations are established firstly, by involving the auxiliary terms. And, the optimal time trajectory with physical constraints is obtained by the dichotomy method. Then, the fuzzy neural network is employed to handle the obstacle-avoidance trajectories generation problem under the different final positions and obstacle positions. An adaptive tracking control method with error constraints is further given to guarantee the precise tracking of the trolley and the jib. It is noteworthy that the proposed method not only constrains the state variables within predefined ranges but also constructs an improved trajectory planning method for the first time to avoid collisions. Additionally, the stability of the system is theoretically proven by the Lyapunov technique and LaSalle’s invariance principle. Finally, several experimental results demonstrate the superiority of the proposed method over comparative approaches in terms of effectiveness and robustness.
{"title":"Obstacle-avoidance trajectory planning based adaptive tracking control for 4DOF tower cranes with tracking error constraints","authors":"Wei Peng, Hui Guo, Menghua Zhang, Chengdong Li, Fang Shang, Zhi Li","doi":"10.1016/j.ymssp.2024.112109","DOIUrl":"https://doi.org/10.1016/j.ymssp.2024.112109","url":null,"abstract":"Due to the tower cranes usually working in an outdoor environment, it is generally unavoidable for the obstacle to exist in the transportation path. Thus, it is critical for the tower crane systems to guarantee their safety and efficiency simultaneously. In this paper, for the 4DOF tower cranes, a novel adaptive tracking control approach is proposed by considering obstacle-avoidance trajectory planning. The state constraint equations are established firstly, by involving the auxiliary terms. And, the optimal time trajectory with physical constraints is obtained by the dichotomy method. Then, the fuzzy neural network is employed to handle the obstacle-avoidance trajectories generation problem under the different final positions and obstacle positions. An adaptive tracking control method with error constraints is further given to guarantee the precise tracking of the trolley and the jib. It is noteworthy that the proposed method not only constrains the state variables within predefined ranges but also constructs an improved trajectory planning method for the first time to avoid collisions. Additionally, the stability of the system is theoretically proven by the Lyapunov technique and LaSalle’s invariance principle. Finally, several experimental results demonstrate the superiority of the proposed method over comparative approaches in terms of effectiveness and robustness.","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"249 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.ymssp.2024.112119
Zejun Zheng, Dongli Song, Weihua Zhang, Xiao Xu, Chao Ma, Wang Cui
The dynamic parameters of high-speed train axle box bearing have time-varying characteristics, it is necessary to investigate the influence of time-varying characteristics on the dynamic response of the bearing. In this paper, based on the time-varying characteristics of the internal and external dynamic parameters of the bearing, a two-degree-of-freedom dynamic model of axle box bearing is established. The dynamic responses of bearings with different ranges of outer raceway defects are analyzed, and the similarities and differences between the varying compliance vibration and outer ring raceway defect fault vibration are compared. The results show that these two vibration modes have the same characteristic frequency, but the contact force between rollers and raceways and vibration acceleration amplitudes are greatly different. Finally, the effectiveness of the established dynamic model is verified through monitoring signal on the operation high-speed railway line.
{"title":"Dynamic response analysis of high-speed train axle box bearing by considering time-varying dynamic parameters","authors":"Zejun Zheng, Dongli Song, Weihua Zhang, Xiao Xu, Chao Ma, Wang Cui","doi":"10.1016/j.ymssp.2024.112119","DOIUrl":"https://doi.org/10.1016/j.ymssp.2024.112119","url":null,"abstract":"The dynamic parameters of high-speed train axle box bearing have time-varying characteristics, it is necessary to investigate the influence of time-varying characteristics on the dynamic response of the bearing. In this paper, based on the time-varying characteristics of the internal and external dynamic parameters of the bearing, a two-degree-of-freedom dynamic model of axle box bearing is established. The dynamic responses of bearings with different ranges of outer raceway defects are analyzed, and the similarities and differences between the varying compliance vibration and outer ring raceway defect fault vibration are compared. The results show that these two vibration modes have the same characteristic frequency, but the contact force between rollers and raceways and vibration acceleration amplitudes are greatly different. Finally, the effectiveness of the established dynamic model is verified through monitoring signal on the operation high-speed railway line.","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"99 1","pages":""},"PeriodicalIF":8.4,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.ymssp.2024.112078
Jingjing Wang , Yuqiang Zheng , Yuhong Ma
This study introduces movable-track nonlinear energy sinks (MT-NESs) featuring customizable restoring forces. MT-NESs employ a novel track-spring configuration where the track parts themselves act as the movable mass, significantly reducing device dimensions and weight. The paper commences with the development of MT-NESs. A small-scale MT-NES is then experimentally realized on a two-story structure under impulsive excitation, validating the accuracy of the numerical model. Subsequently, a design example for seismic protection of the structure is presented, where the track shape, and thus the restoring force of the MT-NES, is designed for specific structure and excitation conditions. Comparative analyses with counterpart devices under seismic and impulsive excitations demonstrate the robust performance of the designed MT-NES, which closely aligns with the design objectives. This study underscores the flexibility of MT-NESs in generating customizable restoring forces within a compact configuration, positioning them as effective solutions for addressing control challenges beyond the capabilities of conventional mass dampers.
{"title":"Movable-track nonlinear energy sinks with customizable restoring forces","authors":"Jingjing Wang , Yuqiang Zheng , Yuhong Ma","doi":"10.1016/j.ymssp.2024.112078","DOIUrl":"10.1016/j.ymssp.2024.112078","url":null,"abstract":"<div><div>This study introduces movable-track nonlinear energy sinks (MT-NESs) featuring customizable restoring forces. MT-NESs employ a novel track-spring configuration where the track parts themselves act as the movable mass, significantly reducing device dimensions and weight. The paper commences with the development of MT-NESs. A small-scale MT-NES is then experimentally realized on a two-story structure under impulsive excitation, validating the accuracy of the numerical model. Subsequently, a design example for seismic protection of the structure is presented, where the track shape, and thus the restoring force of the MT-NES, is designed for specific structure and excitation conditions. Comparative analyses with counterpart devices under seismic and impulsive excitations demonstrate the robust performance of the designed MT-NES, which closely aligns with the design objectives. This study underscores the flexibility of MT-NESs in generating customizable restoring forces within a compact configuration, positioning them as effective solutions for addressing control challenges beyond the capabilities of conventional mass dampers.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112078"},"PeriodicalIF":7.9,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.ymssp.2024.112037
Nasser Ghaderi , Navid Hasheminejad , Seppe Sels , Bart Ribbens , Joris Dirckx , Steve Vanlanduit
This paper provides a comprehensive investigation into characterizing viscoelastic properties in soft materials, focusing on silicone. Conventional measurement techniques such as tensile testing and dynamic mechanical analysis prove inadequate for soft materials. The proposed method utilizes Rayleigh surface wave propagation, employing a laser Doppler vibrometer to measure phase speed and amplitude, induced by air jet pulses in a contactless manner. Usually, a contact probe is used for excitation, which results a higher signal to noise ratio. The study involves a regression analysis to obtain dispersion curves, filtering outcomes with a coefficient of determination threshold above 95% as a quality indicator for the measurements. Mechanical parameters, including complex dynamic modulus and shear modulus components, are determined from Rayleigh and shear complex wave-numbers. Repeatability assessments, including changes in measuring direction, underscore the stability of the experimental setup and sample uniformity. Noteworthy is the comparison of results from the Surface Wave Elastography (SWE) method through an experimental test, a novel aspect in this study. The evaluation method, based on a spring–damper model rooted in the exact solution of Newton’s second law differential equation, serves as a reference. The comparison of mean storage modulus values between the SWE method and the free-loading mass method revealed errors of 6.36% and 10.23% for two tested samples.
本文以硅胶为重点，对表征软材料的粘弹性能进行了全面研究。传统的测量技术，如拉伸测试和动态机械分析，对于软材料是不够的。所提出的方法利用瑞利表面波传播，使用激光多普勒测振仪以非接触方式测量喷气脉冲诱导的相位速度和振幅。通常情况下，使用接触式探头进行激励，信噪比较高。研究涉及回归分析，以获得频散曲线，过滤确定系数阈值高于 95% 的结果，作为测量的质量指标。机械参数，包括复合动态模量和剪切模量成分，由瑞利和剪切复合波数确定。重复性评估（包括测量方向的改变）强调了实验装置的稳定性和样品的均匀性。值得注意的是通过实验测试对表面波弹性成像（SWE）方法的结果进行了比较，这也是本研究的一个新颖之处。该评估方法基于牛顿第二定律微分方程精确解法的弹簧-阻尼模型，可作为参考。通过比较 SWE 法和自由载荷质量法的平均存储模量值，发现两个测试样品的误差分别为 6.36% 和 10.23%。
{"title":"Soft material characterization through surface wave elastography using a laser Doppler vibrometer","authors":"Nasser Ghaderi , Navid Hasheminejad , Seppe Sels , Bart Ribbens , Joris Dirckx , Steve Vanlanduit","doi":"10.1016/j.ymssp.2024.112037","DOIUrl":"10.1016/j.ymssp.2024.112037","url":null,"abstract":"<div><div>This paper provides a comprehensive investigation into characterizing viscoelastic properties in soft materials, focusing on silicone. Conventional measurement techniques such as tensile testing and dynamic mechanical analysis prove inadequate for soft materials. The proposed method utilizes Rayleigh surface wave propagation, employing a laser Doppler vibrometer to measure phase speed and amplitude, induced by air jet pulses in a contactless manner. Usually, a contact probe is used for excitation, which results a higher signal to noise ratio. The study involves a regression analysis to obtain dispersion curves, filtering outcomes with a coefficient of determination threshold above 95% as a quality indicator for the measurements. Mechanical parameters, including complex dynamic modulus and shear modulus components, are determined from Rayleigh and shear complex wave-numbers. Repeatability assessments, including changes in measuring direction, underscore the stability of the experimental setup and sample uniformity. Noteworthy is the comparison of results from the Surface Wave Elastography (SWE) method through an experimental test, a novel aspect in this study. The evaluation method, based on a spring–damper model rooted in the exact solution of Newton’s second law differential equation, serves as a reference. The comparison of mean storage modulus values between the SWE method and the free-loading mass method revealed errors of 6.36% and 10.23% for two tested samples.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112037"},"PeriodicalIF":7.9,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.ymssp.2024.112014
Min Wan, Chuan-Jing Shen, Xiang Qu, Yun Yang, Wei-Hong Zhang
Existing regenerative chatter models orienting for the robotic milling processes only considered the structure mode-induced low frequency vibrations in the plane. This article experimentally reports that obvious -directional low frequency vibrations exist in robotic milling processes with weakly rigid postures, and they can cause multi-cutting phenomenon. Just because of this phenomenon, obvious axial tool-workpiece separation and over-cut phenomena are experimentally observed. This confirms that besides the low frequency vibrations in the plane, those in relation to the direction also greatly affect the stability of the robotic milling process. Hence, a comprehensive dynamic model is systematically established to couple the influences of the low frequency vibrations in relation to both plane and direction of the robotic milling process. The low frequency vibrations in relation to the three directions are quantitatively characterized, and then combined to analyze the radial and axial tool-workpiece separations. For the convenience of study, the tool-workpiece engagement region along the axial depth of cut is divided into a static cutting region and a dynamic cutting region. It is theoretically clarified that the axial over-cut phenomenon (AOCP) leads to an obvious stepped shape of the dynamic cutting region. The multiple delay items, which are redistributed by the complex tool-workpiece engagement states, are derived and then integrated to establish the dynamic governing equation. Subsequently, the principle for obtaining stability lobe diagrams (SLDs) of the robotic milling processes is formulated. A series of robotic milling experiments under different weakly rigid postures confirm that the proposed model can give good prediction accuracy of SLDs.
现有的面向机器人铣削过程的再生颤振模型只考虑了结构模式在 XY 平面上引起的低频振动。本文的实验报告表明，在刚性较弱的机器人铣削过程中，存在明显的 Z 方向低频振动，并会引起多切现象。正因为这种现象，实验观察到了明显的轴向刀具-工件分离和过切现象。这证实了除了 XY 平面的低频振动外，与 Z 方向相关的振动也会极大地影响机器人铣削过程的稳定性。因此，我们系统地建立了一个综合动态模型，以耦合机器人铣削过程中与 XY 平面和 Z 方向有关的低频振动的影响。对与三个方向相关的低频振动进行定量表征，然后结合分析刀具与工件的径向和轴向分离。为便于研究，将刀具与工件沿轴向切深的啮合区域划分为静态切削区域和动态切削区域。理论上，轴向过切现象（AOCP）会导致动态切削区域出现明显的阶梯形状。推导出复杂的刀具与工件啮合状态重新分布的多个延迟项，并对其进行积分，从而建立了动态调控方程。随后，提出了获得机器人铣削过程稳定叶图（SLD）的原理。在不同的弱刚性姿态下进行的一系列机器人铣削实验证实，所提出的模型能提供良好的 SLD 预测精度。
{"title":"Chatter stability of the robotic milling process involving the influences of low frequency vibrations in three directions","authors":"Min Wan, Chuan-Jing Shen, Xiang Qu, Yun Yang, Wei-Hong Zhang","doi":"10.1016/j.ymssp.2024.112014","DOIUrl":"10.1016/j.ymssp.2024.112014","url":null,"abstract":"<div><div>Existing regenerative chatter models orienting for the robotic milling processes only considered the structure mode-induced low frequency vibrations in the <span><math><mrow><mi>X</mi><mi>Y</mi></mrow></math></span> plane. This article experimentally reports that obvious <span><math><mi>Z</mi></math></span>-directional low frequency vibrations exist in robotic milling processes with weakly rigid postures, and they can cause multi-cutting phenomenon. Just because of this phenomenon, obvious axial tool-workpiece separation and over-cut phenomena are experimentally observed. This confirms that besides the low frequency vibrations in the <span><math><mrow><mi>X</mi><mi>Y</mi></mrow></math></span> plane, those in relation to the <span><math><mi>Z</mi></math></span> direction also greatly affect the stability of the robotic milling process. Hence, a comprehensive dynamic model is systematically established to couple the influences of the low frequency vibrations in relation to both <span><math><mrow><mi>X</mi><mi>Y</mi></mrow></math></span> plane and <span><math><mi>Z</mi></math></span> direction of the robotic milling process. The low frequency vibrations in relation to the three directions are quantitatively characterized, and then combined to analyze the radial and axial tool-workpiece separations. For the convenience of study, the tool-workpiece engagement region along the axial depth of cut is divided into a static cutting region and a dynamic cutting region. It is theoretically clarified that the axial over-cut phenomenon (AOCP) leads to an obvious stepped shape of the dynamic cutting region. The multiple delay items, which are redistributed by the complex tool-workpiece engagement states, are derived and then integrated to establish the dynamic governing equation. Subsequently, the principle for obtaining stability lobe diagrams (SLDs) of the robotic milling processes is formulated. A series of robotic milling experiments under different weakly rigid postures confirm that the proposed model can give good prediction accuracy of SLDs.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112014"},"PeriodicalIF":7.9,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.ymssp.2024.112038
Tomasz Haniszewski , Sławomir Bucki , Jerzy Margielewicz , Damian Gąska , Yang Kuang , Grzegorz Litak
This paper presents research on a new type of energy harvester consisting of two parts – the classical tristable system based on a flexible beam and permanent magnets, supplemented by the second part: an additional nonlinear support made of ethylene propylene diene monomer (EPDM). This support is used to amplify the vibration amplitude. As part of this work, laboratory tests on the EPDM material are performed to determine the strain curve. Then, finite element modeling (FEM) software is applied to determine the characteristics of the designed three shapes of the amplifiers and the efficiency of energy harvesting from the vibrations is tested based on the developed dimensionless model. The results are presented with regard to the effective value of the voltage induced on the piezoelectric electrodes and the efficiency factor that compares the tristable energy harvester with the structure developed in this paper. The obtained results allow for the conclusion that the average values of harvested energy over the entire frequency range ω characterize the system, in which the amplifier is two to six times more effective than the system without it. The best results are achieved for a solution based on a full cross-section. Moreover, the introduction of a nonlinear mechanical amplifier caused the classic system based on a magnetic section to obtain the so-called broadband effect over a wide spectrum of frequencies.
{"title":"Energy harvesting system with a hyperelastic mechanical vibration amplifier","authors":"Tomasz Haniszewski , Sławomir Bucki , Jerzy Margielewicz , Damian Gąska , Yang Kuang , Grzegorz Litak","doi":"10.1016/j.ymssp.2024.112038","DOIUrl":"10.1016/j.ymssp.2024.112038","url":null,"abstract":"<div><div>This paper presents research on a new type of energy harvester consisting of two parts – the classical tristable system based on a flexible beam and permanent magnets, supplemented by the second part: an additional nonlinear support made of ethylene propylene diene monomer (EPDM). This support is used to amplify the vibration amplitude. As part of this work, laboratory tests on the EPDM material are performed to determine the strain curve. Then, finite element modeling (FEM) software is applied to determine the characteristics of the designed three shapes of the amplifiers and the efficiency of energy harvesting from the vibrations is tested based on the developed dimensionless model. The results are presented with regard to the effective value of the voltage induced on the piezoelectric electrodes and the efficiency factor that compares the tristable energy harvester with the structure developed in this paper. The obtained results allow for the conclusion that the average values of harvested energy over the entire frequency range <em>ω</em> characterize the system, in which the amplifier is two to six times more effective than the system without it. The best results are achieved for a solution based on a full cross-section. Moreover, the introduction of a nonlinear mechanical amplifier caused the classic system based on a magnetic section to obtain the so-called broadband effect over a wide spectrum of frequencies.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112038"},"PeriodicalIF":7.9,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.ymssp.2024.112036
Bi Li , Zhinong Li , Deqiang He
Previous researchers’ Bearing Fault Diagnosis (BFD) methods often employ signal processing techniques to handle one-dimensional vibration signals, enabling the emergence of recognizable Bearing Fault Features (BFFs) in the Cartesian coordinate system. However, due to noise interference or limited by the manifestation of BFFs, these BFFs often require highly specialized personnel to identify and extract them, making the achievement of fully automated bearing fault diagnosis extremely challenging. Hence, a fully automatic BFD method based on Improved Polar Coordinate (IPC) image texture is proposed. Firstly, the proposed IPC algorithm transforms vibration signals into IPC images with easily recognizable BFFs in the polar coordinate system. Then, automatic image filtering, image texture enhancement, and texture feature extraction are achieved through methods in the field of image processing. Finally, automatic BFD experiments are conducted using extracted IPC image texture features and a neural network. The entire BFD process is fully automatic, and the methods employed are relatively simple and easy to implement, which is highly advantageous for promoting and implementing a real-time fault monitoring system. Experimental results show that the proposed fully automated BFD method based on IPC image texture is effective, achieving an average diagnostic accuracy of 99.4%. This surpasses the 95.0% accuracy of a similar method based on symmetrical polar coordinate image texture and the 98.9% accuracy of an advanced method based on refined composite multi-scale dispersion entropy. Moreover, the proposed method also has significant advantages in diagnosis efficiency compared to the advanced method.
{"title":"A fully automatic bearing fault diagnosis method based on an improved polar coordinate image texture","authors":"Bi Li , Zhinong Li , Deqiang He","doi":"10.1016/j.ymssp.2024.112036","DOIUrl":"10.1016/j.ymssp.2024.112036","url":null,"abstract":"<div><div>Previous researchers’ Bearing Fault Diagnosis (BFD) methods often employ signal processing techniques to handle one-dimensional vibration signals, enabling the emergence of recognizable Bearing Fault Features (BFFs) in the Cartesian coordinate system. However, due to noise interference or limited by the manifestation of BFFs, these BFFs often require highly specialized personnel to identify and extract them, making the achievement of fully automated bearing fault diagnosis extremely challenging. Hence, a fully automatic BFD method based on Improved Polar Coordinate (IPC) image texture is proposed. Firstly, the proposed IPC algorithm transforms vibration signals into IPC images with easily recognizable BFFs in the polar coordinate system. Then, automatic image filtering, image texture enhancement, and texture feature extraction are achieved through methods in the field of image processing. Finally, automatic BFD experiments are conducted using extracted IPC image texture features and a neural network. The entire BFD process is fully automatic, and the methods employed are relatively simple and easy to implement, which is highly advantageous for promoting and implementing a real-time fault monitoring system. Experimental results show that the proposed fully automated BFD method based on IPC image texture is effective, achieving an average diagnostic accuracy of 99.4%. This surpasses the 95.0% accuracy of a similar method based on symmetrical polar coordinate image texture and the 98.9% accuracy of an advanced method based on refined composite multi-scale dispersion entropy. Moreover, the proposed method also has significant advantages in diagnosis efficiency compared to the advanced method.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112036"},"PeriodicalIF":7.9,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Machine learning models face performance degradation when migrating to datasets with different distributions from training data. This challenge limits their applications because recollecting labeled data to retrain models is expensive and time-consuming. Domain generalization (DG) aims to learn a predictive model that can extract invariant features across source domains and then generalize to related but unseen target domains. However, most existing feature-invariant DG methods rely on unrealistic assumptions (e.g., stable feature distribution or no label shift) and simplify the problem to learn either invariant feature marginal or conditional distributions. In practice, both feature and label shifts may exist, rendering these assumptions invalid. This study develops a novel DG method to simultaneously consider conditional, marginal, and label shifts. With Bayes’ theorem, DG is interpreted as a posterior distribution alignment problem, which is derived by the likelihood function, evidence, and prior. The likelihood function and evidence correspond to feature conditional and marginal distributions, respectively, which are estimated by exploiting variational Bayesian inference. The conditional distributions across domains are aligned by minimizing the Kullback–Leibler divergence, and the marginal distributions across domains are aligned through moment minimization. The label prior shift is estimated by the label smoothing mechanism and class-wise prototype learning. Consequently, DG is achieved by aligning the label posterior distribution according to the Bayesian equation. Numerical and experimental examples demonstrate that the developed method outperforms state-of-the-art DG methods in damage detection of both mechanical and civil structures. The method can be extended to DG tasks in other fields.
{"title":"Maximizing model generalization under feature and label shifts for structural damage detection via Bayesian theory","authors":"Xiaoyou Wang , Jinyang Jiao , Xiaoqing Zhou , Yong Xia","doi":"10.1016/j.ymssp.2024.112052","DOIUrl":"10.1016/j.ymssp.2024.112052","url":null,"abstract":"<div><div>Machine learning models face performance degradation when migrating to datasets with different distributions from training data. This challenge limits their applications because recollecting labeled data to retrain models is expensive and time-consuming. Domain generalization (DG) aims to learn a predictive model that can extract invariant features across source domains and then generalize to related but unseen target domains. However, most existing feature-invariant DG methods rely on unrealistic assumptions (e.g., stable feature distribution or no label shift) and simplify the problem to learn either invariant feature marginal or conditional distributions. In practice, both feature and label shifts may exist, rendering these assumptions invalid. This study develops a novel DG method to simultaneously consider conditional, marginal, and label shifts. With Bayes’ theorem, DG is interpreted as a posterior distribution alignment problem, which is derived by the likelihood function, evidence, and prior. The likelihood function and evidence correspond to feature conditional and marginal distributions, respectively, which are estimated by exploiting variational Bayesian inference. The conditional distributions across domains are aligned by minimizing the Kullback–Leibler divergence, and the marginal distributions across domains are aligned through moment minimization. The label prior shift is estimated by the label smoothing mechanism and class-wise prototype learning. Consequently, DG is achieved by aligning the label posterior distribution according to the Bayesian equation. Numerical and experimental examples demonstrate that the developed method outperforms state-of-the-art DG methods in damage detection of both mechanical and civil structures. The method can be extended to DG tasks in other fields.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112052"},"PeriodicalIF":7.9,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.ymssp.2024.112061
Jia-Hao Nie , Dan Li , Hao Wang , Shu-Lin Xiang , Tao Yu , Jian-Xiao Mao
Towards more accurate and easy-to-implement damage detection in large-scale complex structures, a novel acoustic emission (AE) source location method is developed based on artificial potential field-guided rapidly-exploring random tree* (APF-RRT*) and genetic algorithm (GA). APF-RRT*, which combines the excellent obstacle avoidance ability of RRT* with the path planning efficiency of APF, is introduced to adaptively estimate the shortest distances from the damage source to AE sensors. The shortest distances are obtained as the actual propagation distances of waves and then embedded into the modified error function, where GA is employed as an optimization scheme to evaluate the source location via iterations. Through the experiment on a full-scale high-strength bolt joint plate with a series of bolt holes, the effectiveness and superiority of the proposed method were validated. It achieved a better source location performance with lower mean absolute error and standard deviation than the time-of-arrival (TOA) method, delta-T mapping method, and machine learning-improved methods based on Gaussian process (GP) and artificial neural network (ANN), respectively. The primary contributions of the proposed method lay in abandoning the straight-wave-propagation assumption of the traditional TOA method by adaptively taking into account the geometric obstacles in complex structures, and removing the need for a large amount of training data and burdensome pencil lead break (PLB) tests required by data-driven location methods.
为了更准确、更容易地对大型复杂结构进行损伤检测，我们开发了一种基于人工势场引导的快速探索随机树*（APF-RRT*）和遗传算法（GA）的新型声发射（AE）源定位方法。APF-RRT* 结合了 RRT* 的出色避障能力和 APF 的路径规划效率，用于自适应地估计损伤源到 AE 传感器的最短距离。最短距离作为波的实际传播距离，然后嵌入修正误差函数，采用 GA 作为优化方案，通过迭代来评估源位置。通过在带有一系列螺栓孔的全尺寸高强度螺栓连接板上进行实验，验证了所提方法的有效性和优越性。与到达时间（TOA）方法、delta-T 映射方法以及基于高斯过程（GP）和人工神经网络（ANN）的机器学习改进方法相比，该方法的平均绝对误差和标准偏差更小，具有更好的声源定位性能。所提方法的主要贡献在于摒弃了传统 TOA 方法的直波传播假设，自适应地考虑了复杂结构中的几何障碍，并且无需数据驱动定位方法所需的大量训练数据和繁琐的铅笔芯断裂（PLB）测试。
{"title":"Acoustic emission source location in complex structures based on artificial potential field-guided rapidly-exploring random tree* and genetic algorithm","authors":"Jia-Hao Nie , Dan Li , Hao Wang , Shu-Lin Xiang , Tao Yu , Jian-Xiao Mao","doi":"10.1016/j.ymssp.2024.112061","DOIUrl":"10.1016/j.ymssp.2024.112061","url":null,"abstract":"<div><div>Towards more accurate and easy-to-implement damage detection in large-scale complex structures, a novel acoustic emission (AE) source location method is developed based on artificial potential field-guided rapidly-exploring random tree* (APF-RRT*) and genetic algorithm (GA). APF-RRT*, which combines the excellent obstacle avoidance ability of RRT* with the path planning efficiency of APF, is introduced to adaptively estimate the shortest distances from the damage source to AE sensors. The shortest distances are obtained as the actual propagation distances of waves and then embedded into the modified error function, where GA is employed as an optimization scheme to evaluate the source location via iterations. Through the experiment on a full-scale high-strength bolt joint plate with a series of bolt holes, the effectiveness and superiority of the proposed method were validated. It achieved a better source location performance with lower mean absolute error and standard deviation than the time-of-arrival (TOA) method, delta-T mapping method, and machine learning-improved methods based on Gaussian process (GP) and artificial neural network (ANN), respectively. The primary contributions of the proposed method lay in abandoning the straight-wave-propagation assumption of the traditional TOA method by adaptively taking into account the geometric obstacles in complex structures, and removing the need for a large amount of training data and burdensome pencil lead break (PLB) tests required by data-driven location methods.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112061"},"PeriodicalIF":7.9,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-18DOI: 10.1016/j.ymssp.2024.112044
Wen-Rui Zhao , Xu-Yuan Song , Jin-Tong Han , Xiao-Dong Yang , Ye-Wei Zhang
This literature contributes to a theoretical formulation to insight into the rigid-flexible coupling vibration of composite laminated box structures (RFCLBs) in new energy hydrogen-electricity aircraft suffering from complex environments. To achieve this target, a creationary mass model distributed on the interface of the thin-walled box structures is utilized to simulate the RFCLBs by the simplified material coefficient matrix. Based on the Rayleigh-Ritz theory, the dynamic equations of RFCLBs in hygrothermal environments are derived. Owing to rigid mass, four novel vibration patterns which are different from traditional thin-walled box structures have been discovered. More specifically for the new vibration models, a series of theoretical and experiment investigations have been carried out to insight the forming and evolution mechanism of RFCLBs by considering the influence of various masses, sizes and hygrothermal environments in detail. The results indicate that the inherent characteristic of RFCLBs is sensitive to the mass of the rigid component. Under varying external excitations, the modal shapes of RFCLBs exhibit randomness contingent upon specific boundary conditions and their respective order. Additionally, temperature exerts a more pronounced effect on frequency than humidity, which might lead to some unpredictable vibration modes.
{"title":"The rigid-flexible coupling vibration of composite box structure in new energy hydrogen-electricity aircraft with complex circumstance: Theoretical formulation and experiment","authors":"Wen-Rui Zhao , Xu-Yuan Song , Jin-Tong Han , Xiao-Dong Yang , Ye-Wei Zhang","doi":"10.1016/j.ymssp.2024.112044","DOIUrl":"10.1016/j.ymssp.2024.112044","url":null,"abstract":"<div><div>This literature contributes to a theoretical formulation to insight into the rigid-flexible coupling vibration of composite laminated box structures (RFCLBs) in new energy hydrogen-electricity aircraft suffering from complex environments. To achieve this target, a creationary mass model distributed on the interface of the thin-walled box structures is utilized to simulate the RFCLBs by the simplified material coefficient matrix. Based on the Rayleigh-Ritz theory, the dynamic equations of RFCLBs in hygrothermal environments are derived. Owing to rigid mass, four novel vibration patterns which are different from traditional thin-walled box structures have been discovered. More specifically for the new vibration models, a series of theoretical and experiment investigations have been carried out to insight the forming and evolution mechanism of RFCLBs by considering the influence of various masses, sizes and hygrothermal environments in detail. The results indicate that the inherent characteristic of RFCLBs is sensitive to the mass of the rigid component. Under varying external excitations, the modal shapes of RFCLBs exhibit randomness contingent upon specific boundary conditions and their respective order. Additionally, temperature exerts a more pronounced effect on frequency than humidity, which might lead to some unpredictable vibration modes.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112044"},"PeriodicalIF":7.9,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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