Pub Date : 2025-02-04DOI: 10.1016/j.ymssp.2025.112417
Jinshan Huang , Ying Lei , Xiongjun Yang , Xianzhi Li , Kangqian Xu , Feng Wang , Xinghua Chen
Distributed dynamic loads (DDLs) have attracted much attention due to their widespread existence in engineering. However, it remains difficult to measure them directly. Existing DDL identification algorithms have some limitations in terms of dimensionality reduction of DDLs, model order reduction, and robustness. In this study, these issues were addressed and resolved. First, the dimension of continuously DDLs was reduced by combining Lagrange piecewise linear interpolation with the finite element model (FEM), which avoids the dilemma of selecting the type and number of the basis functions. Second, the order of the original model was reduced by combining the substructure method with the complex modal analysis, which avoids the need for repeated transformation between the physical and modal spaces. Finally, with the discrete scheme of the continuous state equation as the factor to be optimized, an adaptive generalized Kalman filtering algorithm with unknown input (AGKF-UI) was derived using the principle of minimum-variance unbiased estimation (MVUE); this step improved the robustness of the identification algorithm. The effectiveness of the proposed method was verified by applying it to three examples: a 20-story shear frame structure, a three-span continuous beam and a plate shell structure. The superiority of the proposed method was demonstrated by comparing it with existing methods.
{"title":"Robust identification of distributed dynamic loads acting on multi-degree-of-freedom structures based on sparse measurement","authors":"Jinshan Huang , Ying Lei , Xiongjun Yang , Xianzhi Li , Kangqian Xu , Feng Wang , Xinghua Chen","doi":"10.1016/j.ymssp.2025.112417","DOIUrl":"10.1016/j.ymssp.2025.112417","url":null,"abstract":"<div><div>Distributed dynamic loads (DDLs) have attracted much attention due to their widespread existence in engineering. However, it remains difficult to measure them directly. Existing DDL identification algorithms have some limitations in terms of dimensionality reduction of DDLs, model order reduction, and robustness. In this study, these issues were addressed and resolved. First, the dimension of continuously DDLs was reduced by combining Lagrange piecewise linear interpolation with the finite element model (FEM), which avoids the dilemma of selecting the type and number of the basis functions. Second, the order of the original model was reduced by combining the substructure method with the complex modal analysis, which avoids the need for repeated transformation between the physical and modal spaces. Finally, with the discrete scheme of the continuous state equation as the factor to be optimized, an adaptive generalized Kalman filtering algorithm with unknown input (AGKF-UI) was derived using the principle of minimum-variance unbiased estimation (MVUE); this step improved the robustness of the identification algorithm. The effectiveness of the proposed method was verified by applying it to three examples: a 20-story shear frame structure, a three-span continuous beam and a plate shell structure. The superiority of the proposed method was demonstrated by comparing it with existing methods.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"228 ","pages":"Article 112417"},"PeriodicalIF":7.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162013","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 : 2025-02-04DOI: 10.1016/j.ymssp.2025.112414
Guanggang Ji , Shaohua Li , Guizhen Feng , Zhengchuan Li , Xiaoguan Shen
With the aim of enhancing the ride comfort and handling stability of vehicles, an improved Takagi-Sugeno (T-S) fuzzy Smith predictive time-delay compensation control strategy (ITSFS) is proposed. Firstly, the vehicle semi-active suspension model with time-delay is established, and the influence of different time-delay sizes is analyzed. Then, combining the theory of time-delay differential equations, the improved Smith predictive time-delay compensation controller is designed. Finally, by combining the semi-active suspension T-S fuzzy controller with the improved Smith predictive time-delay compensation controller, an improved T-S fuzzy Smith predictive time-delay compensation controller for the semi-active suspension system is established. The simulation and experimental results under different operating conditions show that the proposed control strategy can effectively reduce the impact of time-delay on the vehicle semi-active suspension system, significantly improve the dynamic performance of the semi-active suspension system, and have strong adaptive ability to operating conditions. It provides a new method and idea for the research of the semi-active suspension and its control system.
{"title":"Time-delay compensation control and stability analysis of vehicle semi-active suspension systems","authors":"Guanggang Ji , Shaohua Li , Guizhen Feng , Zhengchuan Li , Xiaoguan Shen","doi":"10.1016/j.ymssp.2025.112414","DOIUrl":"10.1016/j.ymssp.2025.112414","url":null,"abstract":"<div><div>With the aim of enhancing the ride comfort and handling stability of vehicles, an improved Takagi-Sugeno (T-S) fuzzy Smith predictive time-delay compensation control strategy (ITSFS) is proposed. Firstly, the vehicle semi-active suspension model with time-delay is established, and the influence of different time-delay sizes is analyzed. Then, combining the theory of time-delay differential equations, the improved Smith predictive time-delay compensation controller is designed. Finally, by combining the semi-active suspension T-S fuzzy controller with the improved Smith predictive time-delay compensation controller, an improved T-S fuzzy Smith predictive time-delay compensation controller for the semi-active suspension system is established. The simulation and experimental results under different operating conditions show that the proposed control strategy can effectively reduce the impact of time-delay on the vehicle semi-active suspension system, significantly improve the dynamic performance of the semi-active suspension system, and have strong adaptive ability to operating conditions. It provides a new method and idea for the research of the semi-active suspension and its control system.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"228 ","pages":"Article 112414"},"PeriodicalIF":7.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162036","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}
The modal analysis of electric stators based on energy principles has been extensively studied. However, existing methods often involve complexities in constructing axial mode shape functions to accommodate various boundary conditions (BCs). This paper presents a weak-form quadrature element method (QEM) for the modal analysis of motor stators, where Lagrange interpolation polynomials are used to construct axial mode shape functions, and Gauss–Lobatto-Legendre (GLL) quadrature is employed to perform the differentiations and integrations in the energy formulation. This approach significantly simplifies the derivation of characteristic equation coefficients and allows for the easy application of different BCs. The effectiveness of the proposed method is validated through modal experiments on both cylindrical shells and real motor stators under various BCs. Due to the invariance of basis in linear space, QEM achieves the same level of accuracy as other series expansion methods, provided that the polynomial order is consistent. This has been demonstrated through comparisons with both the power series expansion method and Chebyshev polynomial expansion method reported in recent literatures. Furthermore, this study identifies a notable computational error in (2,1) mode frequency of cylindrical shells and motor stators under free boundaries. Mutual validations with the transfer matrix method and exact solutions demonstrate that this error does not arise from the solution method itself but is instead inherent to the underlying shell theory.
{"title":"A weak-form quadrature element method for modal analysis of electric motor stators","authors":"Xudong Li, Chenyu Huang, Shihao Zhao, Shuheng Qiu, Wei Liu, Jinhua Chen, Chi Zhang","doi":"10.1016/j.ymssp.2025.112380","DOIUrl":"10.1016/j.ymssp.2025.112380","url":null,"abstract":"<div><div>The modal analysis of electric stators based on energy principles has been extensively studied. However, existing methods often involve complexities in constructing axial mode shape functions to accommodate various boundary conditions (BCs). This paper presents a weak-form quadrature element method (QEM) for the modal analysis of motor stators, where Lagrange interpolation polynomials are used to construct axial mode shape functions, and Gauss–Lobatto-Legendre (GLL) quadrature is employed to perform the differentiations and integrations in the energy formulation. This approach significantly simplifies the derivation of characteristic equation coefficients and allows for the easy application of different BCs. The effectiveness of the proposed method is validated through modal experiments on both cylindrical shells and real motor stators under various BCs. Due to the invariance of basis in linear space, QEM achieves the same level of accuracy as other series expansion methods, provided that the polynomial order is consistent. This has been demonstrated through comparisons with both the power series expansion method and Chebyshev polynomial expansion method reported in recent literatures. Furthermore, this study identifies a notable computational error in (2,1) mode frequency of cylindrical shells and motor stators under free boundaries. Mutual validations with the transfer matrix method and exact solutions demonstrate that this error does not arise from the solution method itself but is instead inherent to the underlying shell theory.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"228 ","pages":"Article 112380"},"PeriodicalIF":7.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162012","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}
The rapid development of the laser ultrasonic technology has promoted non-contact in situ testing of the mechanical properties of materials in high-temperature environments, pursuing enhanced efficiency, precision, and applicability. This paper proposes a laser ultrasound-based technique for characterizing the mechanical properties of materials at high temperatures, and it was applied to determine the variation in the elastic properties of a coating-substrate structure (chromium-Inconel 625) with the temperature. The determination of the mechanical properties of the substrate at different temperatures relies on accurate measurements of the longitudinal and surface wave velocities. The longitudinal wave velocities were modified by considering the effect of thermal expansion on the material thickness during temperature changes, and the mechanical properties of the substrate (Inconel 625) were accurately inverted in the temperature range of 25–1200 °C. It is particularly essential to obtain the mechanical properties of the substrate to measure the elastic constants of the coating. An improved method for inverting the elastic constants of coatings based on dispersion curves is proposed, and a procedure to determine the coating properties is developed based on the Fast Fourier Transform and Green Function Method. The elastic constants of the coating (chromium) at temperatures ranging from 25 °C to 500 °C were accurately measured using the scanning laser source method. This study provides a significant detection scheme for the in situ measurement of mechanical parameters under high-temperature conditions.
{"title":"Mechanical properties measurement of chromium coatings based on laser ultrasonic technology in high-temperature conditions","authors":"Jiajian Meng , Xianke Li , Junrong Li , Haomiao Fang , Zhiyuan Zhu , Zerui Zhao , Enpei Zhao , LiLi Cheng , Jianhai Zhang , Hongwei Zhao","doi":"10.1016/j.ymssp.2025.112421","DOIUrl":"10.1016/j.ymssp.2025.112421","url":null,"abstract":"<div><div>The rapid development of the laser ultrasonic technology has promoted non-contact in situ testing of the mechanical properties of materials in high-temperature environments, pursuing enhanced efficiency, precision, and applicability. This paper proposes a laser ultrasound-based technique for characterizing the mechanical properties of materials at high temperatures, and it was applied to determine the variation in the elastic properties of a coating-substrate structure (chromium-Inconel 625) with the temperature. The determination of the mechanical properties of the substrate at different temperatures relies on accurate measurements of the longitudinal and surface wave velocities. The longitudinal wave velocities were modified by considering the effect of thermal expansion on the material thickness during temperature changes, and the mechanical properties of the substrate (Inconel 625) were accurately inverted in the temperature range of 25–1200 °C. It is particularly essential to obtain the mechanical properties of the substrate to measure the elastic constants of the coating. An improved method for inverting the elastic constants of coatings based on dispersion curves is proposed, and a procedure to determine the coating properties is developed based on the Fast Fourier Transform and Green Function Method. The elastic constants of the coating (chromium) at temperatures ranging from 25 °C to 500 °C were accurately measured using the scanning laser source method. This study provides a significant detection scheme for the in situ measurement of mechanical parameters under high-temperature conditions.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"228 ","pages":"Article 112421"},"PeriodicalIF":7.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162037","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 : 2025-02-03DOI: 10.1016/j.ymssp.2025.112374
Keaton Coletti , R. Benjamin Davis , Ryan Schultz
This paper develops a novel method for reconstructing the full-field response of structural dynamic systems using sparse measurements. The singular value decomposition is applied to a frequency response matrix relating the structural response to physical loads, base motion, or modal loads. The left singular vectors form a non-physical reduced basis that can be used for response reconstruction with far fewer sensors than existing methods. The contributions of the singular vectors to measured response are termed singular-vector loads (SVLs) and are used in a regularized Bayesian framework to generate full-field response estimates and confidence intervals. The reconstruction framework is applicable to the estimation of single data records and power spectral densities from multiple records. Reconstruction is successfully performed in configurations where the number of SVLs to identify is less than, equal to, and greater than the number of sensors used for reconstruction. In a simulation featuring a seismically excited shear structure, SVL reconstruction significantly outperforms modal FRF-based reconstruction and successfully estimates full-field responses with as few as two uniaxial accelerometers. SVL reconstruction is further verified in a simulation featuring an acoustically excited cylinder. Finally, response reconstruction and uncertainty quantification are performed on an experimental structure with three shaker inputs and 27 triaxial accelerometer outputs.
{"title":"Structural response reconstruction using a system-equivalent singular vector basis","authors":"Keaton Coletti , R. Benjamin Davis , Ryan Schultz","doi":"10.1016/j.ymssp.2025.112374","DOIUrl":"10.1016/j.ymssp.2025.112374","url":null,"abstract":"<div><div>This paper develops a novel method for reconstructing the full-field response of structural dynamic systems using sparse measurements. The singular value decomposition is applied to a frequency response matrix relating the structural response to physical loads, base motion, or modal loads. The left singular vectors form a non-physical reduced basis that can be used for response reconstruction with far fewer sensors than existing methods. The contributions of the singular vectors to measured response are termed singular-vector loads (SVLs) and are used in a regularized Bayesian framework to generate full-field response estimates and confidence intervals. The reconstruction framework is applicable to the estimation of single data records and power spectral densities from multiple records. Reconstruction is successfully performed in configurations where the number of SVLs to identify is less than, equal to, and greater than the number of sensors used for reconstruction. In a simulation featuring a seismically excited shear structure, SVL reconstruction significantly outperforms modal FRF-based reconstruction and successfully estimates full-field responses with as few as two uniaxial accelerometers. SVL reconstruction is further verified in a simulation featuring an acoustically excited cylinder. Finally, response reconstruction and uncertainty quantification are performed on an experimental structure with three shaker inputs and 27 triaxial accelerometer outputs.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"227 ","pages":"Article 112374"},"PeriodicalIF":7.9,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135380","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 : 2025-02-02DOI: 10.1016/j.ymssp.2025.112420
Taylan Karaağaçlı, Furkan K. Çelik
{"title":"Corrigendum to “Modal analysis of non-conservative systems with friction-induced strong nonlinear damping by using response-controlled testing” [Mech. Syst. Signal Process. 221 (2024) 111718]","authors":"Taylan Karaağaçlı, Furkan K. Çelik","doi":"10.1016/j.ymssp.2025.112420","DOIUrl":"10.1016/j.ymssp.2025.112420","url":null,"abstract":"","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"227 ","pages":"Article 112420"},"PeriodicalIF":7.9,"publicationDate":"2025-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349924","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 : 2025-02-01DOI: 10.1016/j.ymssp.2024.112090
Robert B. Randall , Jérôme Antoni
Simon Braun was one of the first to recognise the special requirements for processing of signals from mechanical systems, which was why he launched the journal Mechanical Systems and Signal Processing. Mechanical engineers are typically not well trained in signal processing, so signal processing specialists are often recruited from other areas, e.g. electrical engineering, speech processing, acoustics, which often have different requirements. A very important application area of signal processing in mechanical engineering (and mechatronics) is robotics and active control. This requires causal processing in real-time, but that places restrictions on the results, since causal filters have poor characteristics and phase distortion. There are also problems with differentiation, integration, and Hilbert transformation when performed directly in the time domain. Machine Condition Monitoring is another very important area of signal processing for mechanical engineers. This paper shows that causal signal processing is not only not required for Machine Condition Monitoring, even for online monitoring of critical machines, but gives problems and distortions that can be avoided with non-causal signal processing. The paper illustrates the advantages gained using non-causal processing, mostly based on FFT (fast Fourier transform) analysis, for ideal filtration with zero phase shift, as well as error-free differentiation/integration and Hilbert transformation via the frequency domain. However, the circularity of the (non-causal) FFT algorithm gives “wraparound effects”, which must be mitigated. The paper has a short discussion of the situations, apart from active control, where causal processing is of advantage, such as octave-based filtration, and real-time zoom as a precursor to FFT analysis. Finally, the paper discusses the special requirements of machine health indicators obtained by signal processing, because unlike structural health monitoring, they are based more on changes in forcing functions, varying greatly between different machines and components, and not just on dynamic (i.e. modal) properties.
{"title":"Choosing the right signal processing tools for mechanical systems","authors":"Robert B. Randall , Jérôme Antoni","doi":"10.1016/j.ymssp.2024.112090","DOIUrl":"10.1016/j.ymssp.2024.112090","url":null,"abstract":"<div><div>Simon Braun was one of the first to recognise the special requirements for processing of signals from mechanical systems, which was why he launched the journal Mechanical Systems and Signal Processing. Mechanical engineers are typically not well trained in signal processing, so signal processing specialists are often recruited from other areas, e.g. electrical engineering, speech processing, acoustics, which often have different requirements. A very important application area of signal processing in mechanical engineering (and mechatronics) is robotics and active control. This requires causal processing in real-time, but that places restrictions on the results, since causal filters have poor characteristics and phase distortion. There are also problems with differentiation, integration, and Hilbert transformation when performed directly in the time domain. Machine Condition Monitoring is another very important area of signal processing for mechanical engineers. This paper shows that causal signal processing is not only not required for Machine Condition Monitoring, even for online monitoring of critical machines, but gives problems and distortions that can be avoided with non-causal signal processing. The paper illustrates the advantages gained using non-causal processing, mostly based on FFT (fast Fourier transform) analysis, for ideal filtration with zero phase shift, as well as error-free differentiation/integration and Hilbert transformation via the frequency domain. However, the circularity of the (non-causal) FFT algorithm gives “wraparound effects”, which must be mitigated. The paper has a short discussion of the situations, apart from active control, where causal processing is of advantage, such as octave-based filtration, and real-time zoom as a precursor to FFT analysis. Finally, the paper discusses the special requirements of machine health indicators obtained by signal processing, because unlike structural health monitoring, they are based more on changes in forcing functions, varying greatly between different machines and components, and not just on dynamic (i.e. modal) properties.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"224 ","pages":"Article 112090"},"PeriodicalIF":7.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143094446","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 : 2025-02-01DOI: 10.1016/j.ymssp.2025.112338
Julian Staiger , Rafael S.O. Dias , Alessandro Zucchini , Milena Martarelli , Frank Naets
In this paper, we investigate the usage of the augmented Kalman filter to solve inverse problems by exploiting modal state-space models to characterize forces in a virtual point. Modular engineering approaches require precise interface force characterization, which is challenging to obtain in operation due to the inaccessibility of the interface. However, forces transmitting through connecting components play a crucial role in sound & vibration engineering as well as in lifetime analysis and control. In this work, we compare the estimation of forces transmitting through a rubber mount by using two different strategies that rely on the use of the Virtual Point Transformation (VPT) method. In the first strategy, the forces of interest are determined by applying VPT to transform the estimated set of applied forces. Conversely, in the second methodology, the forces of interest are directly estimated by exploiting input-reduced models defined using the VPT method. This strategy requires the use of an augmented state-space representation of input-reduced models, which is derived in this article. Moreover, a novel approach to determine state-space models reduced into virtual points is proposed, leading to the computation of lower-order models compared to the ones computed with the state-of-the-art technique. The frequency-dependent estimation error of the Augmented Kalman Filter (AKF) scheme, stemming from modelling errors, is derived in a general sense for the cases where displacement and acceleration measurements are exploited. It is shown that the VPT introduces a frequency-dependent error term that biases the estimation obtained with the input-reduced model. This theoretical frequency-dependent error is illustrated in a numerical example, and the results obtained using unreduced and input-reduced models are compared and analysed. Subsequently, an experimental example is analysed, focusing on an industrial rubber bushing. The excitation effects of the forces applied in this component are reconstructed at pre-defined virtual points in both time and frequency domains. Good input estimates are obtained for all kinds of excitation in the time and frequency domains. However, it is found that the results obtained with the input-reduced model are less accurate due to the frequency-dependent error stemming from the VPT, which validates the performed theoretical analysis on the frequency-dependent estimation error of the AKF.
{"title":"Advancements and frequency domain error analysis for state-input estimation in virtual points via the augmented Kalman filter","authors":"Julian Staiger , Rafael S.O. Dias , Alessandro Zucchini , Milena Martarelli , Frank Naets","doi":"10.1016/j.ymssp.2025.112338","DOIUrl":"10.1016/j.ymssp.2025.112338","url":null,"abstract":"<div><div>In this paper, we investigate the usage of the augmented Kalman filter to solve inverse problems by exploiting modal state-space models to characterize forces in a virtual point. Modular engineering approaches require precise interface force characterization, which is challenging to obtain in operation due to the inaccessibility of the interface. However, forces transmitting through connecting components play a crucial role in sound & vibration engineering as well as in lifetime analysis and control. In this work, we compare the estimation of forces transmitting through a rubber mount by using two different strategies that rely on the use of the Virtual Point Transformation (VPT) method. In the first strategy, the forces of interest are determined by applying VPT to transform the estimated set of applied forces. Conversely, in the second methodology, the forces of interest are directly estimated by exploiting input-reduced models defined using the VPT method. This strategy requires the use of an augmented state-space representation of input-reduced models, which is derived in this article. Moreover, a novel approach to determine state-space models reduced into virtual points is proposed, leading to the computation of lower-order models compared to the ones computed with the state-of-the-art technique. The frequency-dependent estimation error of the Augmented Kalman Filter (AKF) scheme, stemming from modelling errors, is derived in a general sense for the cases where displacement and acceleration measurements are exploited. It is shown that the VPT introduces a frequency-dependent error term that biases the estimation obtained with the input-reduced model. This theoretical frequency-dependent error is illustrated in a numerical example, and the results obtained using unreduced and input-reduced models are compared and analysed. Subsequently, an experimental example is analysed, focusing on an industrial rubber bushing. The excitation effects of the forces applied in this component are reconstructed at pre-defined virtual points in both time and frequency domains. Good input estimates are obtained for all kinds of excitation in the time and frequency domains. However, it is found that the results obtained with the input-reduced model are less accurate due to the frequency-dependent error stemming from the VPT, which validates the performed theoretical analysis on the frequency-dependent estimation error of the AKF.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"227 ","pages":"Article 112338"},"PeriodicalIF":7.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077500","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 : 2025-02-01DOI: 10.1016/j.ymssp.2025.112369
Weiqi Tong , Chenheng Lin , Kelin Wu , Linlin Cao , Rui Wu , Dazhuan Wu
The propeller noise is the primary source of radiated noise from surface ships and submarines. Demodulation techniques such as Detection of Envelope Modulation On Noise (DEMON), narrowband demodulation, and cyclostationary analysis can be used to analyze this noise. However, capturing the characteristic modulation frequencies within the envelope spectrum can be challenging due to far-field effects and complex interference noise. To tackle this challenge, this paper proposes an advanced spectral quantity called the Periodic Sparsity Envelope Spectrum (PSES), which is specifically designed to extract the specific characteristic frequencies of underwater propellers. Firstly, the exact characteristic frequencies are determined using correlated kurtosis with prior knowledge of candidate frequencies. Secondly, a novel adaptive weighting function is proposed based on the periodic sparsity of spectral coherence along the cyclic frequency axis. Moreover, the equal-scale Receiver Operating Characteristic (eROC) indicator is developed to evaluate the demodulation capabilities of different methods and facilitate the automatic detection of the characteristic modulation frequencies of propellers. Ultimately, simulations and experiments on propellers of the water tunnel as well as merchant ships are conducted to verify the effectiveness and superiority of the proposed PSES method.
{"title":"Periodic sparsity envelope spectrum: An advanced spectral quantity for passive acoustic detection of underwater propeller based on prior information of candidate frequencies","authors":"Weiqi Tong , Chenheng Lin , Kelin Wu , Linlin Cao , Rui Wu , Dazhuan Wu","doi":"10.1016/j.ymssp.2025.112369","DOIUrl":"10.1016/j.ymssp.2025.112369","url":null,"abstract":"<div><div>The propeller noise is the primary source of radiated noise from surface ships and submarines. Demodulation techniques such as Detection of Envelope Modulation On Noise (DEMON), narrowband demodulation, and cyclostationary analysis can be used to analyze this noise. However, capturing the characteristic modulation frequencies within the envelope spectrum can be challenging due to far-field effects and complex interference noise. To tackle this challenge, this paper proposes an advanced spectral quantity called the Periodic Sparsity Envelope Spectrum (PSES), which is specifically designed to extract the specific characteristic frequencies of underwater propellers. Firstly, the exact characteristic frequencies are determined using correlated kurtosis with prior knowledge of candidate frequencies. Secondly, a novel adaptive weighting function is proposed based on the periodic sparsity of spectral coherence along the cyclic frequency axis. Moreover, the equal-scale Receiver Operating Characteristic (eROC) indicator is developed to evaluate the demodulation capabilities of different methods and facilitate the automatic detection of the characteristic modulation frequencies of propellers. Ultimately, simulations and experiments on propellers of the water tunnel as well as merchant ships are conducted to verify the effectiveness and superiority of the proposed PSES method.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"227 ","pages":"Article 112369"},"PeriodicalIF":7.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077503","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 : 2025-02-01DOI: 10.1016/j.ymssp.2025.112407
Hongbing Wang, Shiqian Chen, Wanming Zhai
Recently, an adaptive divide-and-conquer method called variational generalized nonlinear mode decomposition (VGNMD) has been proposed to simultaneously extract chirp modes and dispersive modes from non-stationary signals. However, similar to numerous signal analysis techniques, the VGNMD is unsuitable for analyzing complicated non-stationary signals with crossed modes in mechanical systems because it is based on the assumption that signal modes are strictly separated in the time–frequency (TF) plane. In this paper, an improved VGNMD (I-VGNMD) method is proposed to address this issue. Firstly, considering the advantages of mathematical morphology in image feature extraction, the I-VGNMD introduces a TF-skeleton extraction technique to obtain complete TF skeletons containing crossing features from the TF distribution of the signal. Next, according to the pixel connectivity, a weighted directional skeleton tracking strategy is developed to adaptively select the skeleton tracking path and correctly separate the crossed TF skeletons. Finally, the separated independent skeletons are used as initial instantaneous frequencies or group delays to drive the divide-and-conquer decomposition framework of VGNMD for accurate mode reconstruction. Simulated examples and real-life applications to railway wheel/rail fault diagnosis and rotating target detection are considered to demonstrate the effectiveness of the proposed method.
{"title":"Improved variational generalized nonlinear mode decomposition for separating crossed chirp modes and dispersive modes of non-stationary signals in mechanical systems","authors":"Hongbing Wang, Shiqian Chen, Wanming Zhai","doi":"10.1016/j.ymssp.2025.112407","DOIUrl":"10.1016/j.ymssp.2025.112407","url":null,"abstract":"<div><div>Recently, an adaptive divide-and-conquer method called variational generalized nonlinear mode decomposition (VGNMD) has been proposed to simultaneously extract chirp modes and dispersive modes from non-stationary signals. However, similar to numerous signal analysis techniques, the VGNMD is unsuitable for analyzing complicated non-stationary signals with crossed modes in mechanical systems because it is based on the assumption that signal modes are strictly separated in the time–frequency (TF) plane. In this paper, an improved VGNMD (I-VGNMD) method is proposed to address this issue. Firstly, considering the advantages of mathematical morphology in image feature extraction, the I-VGNMD introduces a TF-skeleton extraction technique to obtain complete TF skeletons containing crossing features from the TF distribution of the signal. Next, according to the pixel connectivity, a weighted directional skeleton tracking strategy is developed to adaptively select the skeleton tracking path and correctly separate the crossed TF skeletons. Finally, the separated independent skeletons are used as initial instantaneous frequencies or group delays to drive the divide-and-conquer decomposition framework of VGNMD for accurate mode reconstruction. Simulated examples and real-life applications to railway wheel/rail fault diagnosis and rotating target detection are considered to demonstrate the effectiveness of the proposed method.</div></div>","PeriodicalId":51124,"journal":{"name":"Mechanical Systems and Signal Processing","volume":"227 ","pages":"Article 112407"},"PeriodicalIF":7.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077634","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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