Pub Date : 2023-01-12DOI: 10.1177/14613484231151273
Deshi Meng, Lijun Li, Zhenhua Wu
Acoustic metamaterials with both ventilation and broadband asymmetric absorption have demonstrated great scientific significance and promising applicability. In this work, we design an asymmetric absorbing cell (AAC) consisting of a pair of detuned Helmholtz resonators (HRs) connected by sound channels that allows airflow with a ventilation ratio (ventilation area divided by sound incidence area) of 40%, which can achieve near-perfect sound absorption in the operating frequency range when sound waves are incident from the left port. However, when incident on the right port, the acoustic absorption coefficient does not exceed 40% at most, so asymmetric absorption is achieved. In addition, we form parallel three-cell asymmetric absorber (PTAA) by paralleling three AACs, which have broadband asymmetric absorption compared to AAC. Furthermore, we design multi-asymmetric absorber (MAA), which can achieve broadband asymmetric absorption range from 1000 Hz to 1750 Hz, and also allow air circulation. Moreover, experimental validation is conducted to demonstrate the effectiveness of fabricated MAA by 3D printing technology. Our designs open potential possibilities for developing ventilated functional devices capable of absorbing sound asymmetrically.
{"title":"Helmholtz resonator-based acoustic metamaterials enabling broadband asymmetric sound absorption and ventilation","authors":"Deshi Meng, Lijun Li, Zhenhua Wu","doi":"10.1177/14613484231151273","DOIUrl":"https://doi.org/10.1177/14613484231151273","url":null,"abstract":"Acoustic metamaterials with both ventilation and broadband asymmetric absorption have demonstrated great scientific significance and promising applicability. In this work, we design an asymmetric absorbing cell (AAC) consisting of a pair of detuned Helmholtz resonators (HRs) connected by sound channels that allows airflow with a ventilation ratio (ventilation area divided by sound incidence area) of 40%, which can achieve near-perfect sound absorption in the operating frequency range when sound waves are incident from the left port. However, when incident on the right port, the acoustic absorption coefficient does not exceed 40% at most, so asymmetric absorption is achieved. In addition, we form parallel three-cell asymmetric absorber (PTAA) by paralleling three AACs, which have broadband asymmetric absorption compared to AAC. Furthermore, we design multi-asymmetric absorber (MAA), which can achieve broadband asymmetric absorption range from 1000 Hz to 1750 Hz, and also allow air circulation. Moreover, experimental validation is conducted to demonstrate the effectiveness of fabricated MAA by 3D printing technology. Our designs open potential possibilities for developing ventilated functional devices capable of absorbing sound asymmetrically.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"72 1","pages":"1242 - 1250"},"PeriodicalIF":2.3,"publicationDate":"2023-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90560782","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 measurements derived from damaged conditions are difficult to acquire in actual structures, which limits the applicability of supervised damage detection methods. In this study, an unsupervised damage detection method that leverages an improved generative adversarial network (IGAN) and cloud model (CM) is proposed. This method only needs the data in the healthy state of the structure for model training, which can solve the above problems. Firstly, an IGAN model is established, which uses the encoder-decoder-encoder generative network to encode, reconstruct and re-encode the structural response in healthy state. The essential features hidden in complex data are learned by minimizing the distance between the real response and the reconstructed response, and the distance between the latent vectors obtained after two different encodings. During the test phase, when unknown state data is input into the model, the differences of the latent features of the two different codes can be used to preliminarily judge whether the structure is damaged. In addition, CM theory is used to further quantify structural damage and solve the problem of damage misjudgment caused by measurement noise, model parameters, feature selection, and other uncertain factors. The effectiveness of the proposed damage detection method is verified by Phase I IASC-ASCE benchmark structure and a bridge health monitoring benchmark model. The results prove that the proposed method can accurately detect the damage that has occurred.
{"title":"Unsupervised structural damage detection based on an improved generative adversarial network and cloud model","authors":"Yong-peng Luo, Xu Guo, Lin-kun Wang, Jin-ling Zheng, Jingliang Liu, Fei-yu Liao","doi":"10.1177/14613484221150804","DOIUrl":"https://doi.org/10.1177/14613484221150804","url":null,"abstract":"The measurements derived from damaged conditions are difficult to acquire in actual structures, which limits the applicability of supervised damage detection methods. In this study, an unsupervised damage detection method that leverages an improved generative adversarial network (IGAN) and cloud model (CM) is proposed. This method only needs the data in the healthy state of the structure for model training, which can solve the above problems. Firstly, an IGAN model is established, which uses the encoder-decoder-encoder generative network to encode, reconstruct and re-encode the structural response in healthy state. The essential features hidden in complex data are learned by minimizing the distance between the real response and the reconstructed response, and the distance between the latent vectors obtained after two different encodings. During the test phase, when unknown state data is input into the model, the differences of the latent features of the two different codes can be used to preliminarily judge whether the structure is damaged. In addition, CM theory is used to further quantify structural damage and solve the problem of damage misjudgment caused by measurement noise, model parameters, feature selection, and other uncertain factors. The effectiveness of the proposed damage detection method is verified by Phase I IASC-ASCE benchmark structure and a bridge health monitoring benchmark model. The results prove that the proposed method can accurately detect the damage that has occurred.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"11 1","pages":"1501 - 1518"},"PeriodicalIF":2.3,"publicationDate":"2023-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87487325","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}
Pub Date : 2023-01-11DOI: 10.1177/14613484221126365
Yang Liu, Yang Xu, Zhi-hao Wang
Frequent vibration events on the long stay cables highlight the need to control their multi-mode vibrations. Compared to commonly used viscous dampers for cable vibration control, the negative stiffness damper (NSD) demonstrates its superior performance. However, a single NSD is incapable of providing sufficient supplemental damping for a super-long cable, especially for the multi-mode vibration mitigation. The combined internal high damping rubber (HDR) dampers and the external NSD for cable vibration control is proposed to achieve better multi-mode control performance in this study. First, the complex modal analysis of a taut cable coupled with an external NSD and two internal HDR dampers is conducted to reveal the coupling performance of the damping system. The asymptotic and iterative solutions of transcendental equation obtained in complex modal analysis are derived, respectively. Subsequently, the comparison of asymptotic and iterative solutions verifies the applicability of asymptotic solutions. Finally, parametric studies are performed to investigate the effect of the parameters of NSD and the coupling configuration on their combined control performance. Results show that the coupling schemes with different configurations can possess a wider effective modal range or a better damping effect in the narrower modal ranges according to different damping targets. It provides a diversified solution for multi-mode damping enhancement of stay cables.
{"title":"Free vibration of a taut cable with internal high damping rubber dampers and an external negative stiffness damper","authors":"Yang Liu, Yang Xu, Zhi-hao Wang","doi":"10.1177/14613484221126365","DOIUrl":"https://doi.org/10.1177/14613484221126365","url":null,"abstract":"Frequent vibration events on the long stay cables highlight the need to control their multi-mode vibrations. Compared to commonly used viscous dampers for cable vibration control, the negative stiffness damper (NSD) demonstrates its superior performance. However, a single NSD is incapable of providing sufficient supplemental damping for a super-long cable, especially for the multi-mode vibration mitigation. The combined internal high damping rubber (HDR) dampers and the external NSD for cable vibration control is proposed to achieve better multi-mode control performance in this study. First, the complex modal analysis of a taut cable coupled with an external NSD and two internal HDR dampers is conducted to reveal the coupling performance of the damping system. The asymptotic and iterative solutions of transcendental equation obtained in complex modal analysis are derived, respectively. Subsequently, the comparison of asymptotic and iterative solutions verifies the applicability of asymptotic solutions. Finally, parametric studies are performed to investigate the effect of the parameters of NSD and the coupling configuration on their combined control performance. Results show that the coupling schemes with different configurations can possess a wider effective modal range or a better damping effect in the narrower modal ranges according to different damping targets. It provides a diversified solution for multi-mode damping enhancement of stay cables.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"26 1","pages":"1018 - 1034"},"PeriodicalIF":2.3,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83530626","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}
Pub Date : 2023-01-10DOI: 10.1177/14613484221145183
Jiale Peng, Yushu Bian, Dongbo Tian, P. Liu, Zhihui Gao
Wind turbine drivetrains play a fundamental role in converting wind power into electrical energy. The gearbox is one of the most important and expensive components in a wind turbine drivetrain. Since flexible suspensions mounted on the gearbox are mainly designed for isolating vibration transfer to other turbine components, the gearbox itself still suffers from complicated whole-body vibration. In view of this, a vibration absorption method based on modal interaction is put forward to alleviate the whole-body vibration of the wind turbine gearbox with flexible suspensions. A vibration absorber with adjustable control parameters is utilized to establish modal coupling with the wind turbine gearbox. Internal resonance is analyzed and used to construct a modal interaction mechanism between the vibration absorber mode and the controlled gearbox mode. With the help of modal interaction, the vibration energy of the controlled gearbox mode is successfully absorbed by the vibration absorber mode and effectively dissipated by the damping of the vibration absorber mode. Through numerical simulations and virtual prototyping simulations, its vibration alleviation performance is verified. Since the proposed method is designed in terms of the controlled mode of the wind turbine gearbox rather than external excitations, it is suitable for applications in a complicated working environment. Besides, the proposed method aims to transfer and dissipate vibration energy through nonlinear modal interaction rather than suppress vibration via external energy, and thus can effectively deal with strong vibration problems. More importantly, it can easily work together with the existing vibration isolation method and further alleviate the whole-body vibration of the gearbox. This research will contribute to improving the reliability and service life of wind turbine gearboxes.
{"title":"Vibration alleviation for wind turbine gearbox with flexible suspensions based on modal interaction","authors":"Jiale Peng, Yushu Bian, Dongbo Tian, P. Liu, Zhihui Gao","doi":"10.1177/14613484221145183","DOIUrl":"https://doi.org/10.1177/14613484221145183","url":null,"abstract":"Wind turbine drivetrains play a fundamental role in converting wind power into electrical energy. The gearbox is one of the most important and expensive components in a wind turbine drivetrain. Since flexible suspensions mounted on the gearbox are mainly designed for isolating vibration transfer to other turbine components, the gearbox itself still suffers from complicated whole-body vibration. In view of this, a vibration absorption method based on modal interaction is put forward to alleviate the whole-body vibration of the wind turbine gearbox with flexible suspensions. A vibration absorber with adjustable control parameters is utilized to establish modal coupling with the wind turbine gearbox. Internal resonance is analyzed and used to construct a modal interaction mechanism between the vibration absorber mode and the controlled gearbox mode. With the help of modal interaction, the vibration energy of the controlled gearbox mode is successfully absorbed by the vibration absorber mode and effectively dissipated by the damping of the vibration absorber mode. Through numerical simulations and virtual prototyping simulations, its vibration alleviation performance is verified. Since the proposed method is designed in terms of the controlled mode of the wind turbine gearbox rather than external excitations, it is suitable for applications in a complicated working environment. Besides, the proposed method aims to transfer and dissipate vibration energy through nonlinear modal interaction rather than suppress vibration via external energy, and thus can effectively deal with strong vibration problems. More importantly, it can easily work together with the existing vibration isolation method and further alleviate the whole-body vibration of the gearbox. This research will contribute to improving the reliability and service life of wind turbine gearboxes.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"320 1","pages":"1390 - 1418"},"PeriodicalIF":2.3,"publicationDate":"2023-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76284927","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}
Pub Date : 2023-01-04DOI: 10.1177/14613484221149518
Y. El‐Dib, N. S. Elgazery, Nada S Gad
The impetus for the current investigation relates to the implementation of an efficient novel technique to obtain a time-delayed vibration control analytical solution. The current technique follows simple and easy-to-apply criteria. This technique is based on converting the nonlinear time-delayed Van der Pol (VDP)-Duffing oscillator to an equivalent linear one. Details of the conversion to an equivalent linear ordinary differential equation are mentioned. The convergence between the numerical outcomes and the analytic solution is achieved and gives a satisfying accuracy of the equivalent result.
{"title":"A novel technique to obtain a time-delayed vibration control analytical solution with simulation of He’s formula","authors":"Y. El‐Dib, N. S. Elgazery, Nada S Gad","doi":"10.1177/14613484221149518","DOIUrl":"https://doi.org/10.1177/14613484221149518","url":null,"abstract":"The impetus for the current investigation relates to the implementation of an efficient novel technique to obtain a time-delayed vibration control analytical solution. The current technique follows simple and easy-to-apply criteria. This technique is based on converting the nonlinear time-delayed Van der Pol (VDP)-Duffing oscillator to an equivalent linear one. Details of the conversion to an equivalent linear ordinary differential equation are mentioned. The convergence between the numerical outcomes and the analytic solution is achieved and gives a satisfying accuracy of the equivalent result.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"60 1","pages":"1379 - 1389"},"PeriodicalIF":2.3,"publicationDate":"2023-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82315507","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}
Pub Date : 2022-12-27DOI: 10.1177/14613484221148048
Thanh Q. Nguyen, Tuan-Anh Nguyen, Thuy T. Nguyen
A defective structure has been evaluated and identified in beam models’ deflection measurement signals in much research. However, many results have not been optimally exploited and evaluated to find new parameters for data excavation. This manuscript proposes a cumulative welding model and a cumulative circle of deflection signals for a defective beam under the impact of a moving force. Based on this evaluation model, the manuscript recognizes that the speed of the moving force will determine the regression speed of the received datasets, which is considered the basis for showing the working ability of a beam structure with defects. Moreover, the structure’s cumulative regression circle also shows its resilience in that structure after the impact of the load. The development of defects in the structure will depend on both the structure’s level and resilience after each bearing-load cycle. Our research has shown us that the method of evaluation and use of both the cumulative model and cumulative circle from the deflection’s measured value have yielded more results compared to the previous method. This research can evaluate many defects in different situations while simultaneously evaluating many types of structures.
{"title":"Structural health monitoring based on the cumulative function and cumulative circle of a defective beam under a moving load","authors":"Thanh Q. Nguyen, Tuan-Anh Nguyen, Thuy T. Nguyen","doi":"10.1177/14613484221148048","DOIUrl":"https://doi.org/10.1177/14613484221148048","url":null,"abstract":"A defective structure has been evaluated and identified in beam models’ deflection measurement signals in much research. However, many results have not been optimally exploited and evaluated to find new parameters for data excavation. This manuscript proposes a cumulative welding model and a cumulative circle of deflection signals for a defective beam under the impact of a moving force. Based on this evaluation model, the manuscript recognizes that the speed of the moving force will determine the regression speed of the received datasets, which is considered the basis for showing the working ability of a beam structure with defects. Moreover, the structure’s cumulative regression circle also shows its resilience in that structure after the impact of the load. The development of defects in the structure will depend on both the structure’s level and resilience after each bearing-load cycle. Our research has shown us that the method of evaluation and use of both the cumulative model and cumulative circle from the deflection’s measured value have yielded more results compared to the previous method. This research can evaluate many defects in different situations while simultaneously evaluating many types of structures.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"34 1","pages":"729 - 745"},"PeriodicalIF":2.3,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74068534","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}
Pub Date : 2022-12-26DOI: 10.1177/14613484221135866
Minghe Qu, Qing Yang, Shaopei Wu, Wangcai Ding, Jie Li, Guofang Li
The precision instruments and equipment are often utilized in low-frequency and micro-amplitude vibration systems, in which many vibration isolators of rubber materials are widely used. Ignoring the low-frequency amplitude will result in errors in the fatigue life design of the vibration isolators and predicting the dynamic response of each frequency band accurately becomes necessary. However, integer-order models cannot describe the frequency dependence of rubber materials, while the fractional-order models can describe it instead. On the other hand, the elastic restoring force is strongly nonlinear under large deformation, and the vibration of the nonlinear system contains multiple harmonic components. In order to solve those issues, the fractional nonlinear Nishimura model is used to characterize the constitutive relation of vibration isolators such as air springs, which are made of carbon black filled natural rubber. The high-order harmonic balance method is used to obtain the steady-state response of the vibration system, while the fourth-order Runge–Kutta method is applied to simulate the dynamic response of the system in the low-frequency region, and the Lyapunov exponent is used to determine the stability of the system. Furthermore, the influence of parameters on the amplitude–frequency characteristics of different frequency bands is also studied, and a method to solve the optimal damping coefficient is proposed based on the primary resonance amplitude–frequency curves. The results show that there is a diversity of periodic motions in the process of adjacent super-harmonic resonance transition. Numerical simulations also demonstrate that multi-periodic motions coexist in the system. The motion transition law between the polymorphic coexistence region and its adjacent regions is summarized.
{"title":"Analysis of super-harmonic resonance and periodic motion transition of fractional nonlinear vibration isolation system","authors":"Minghe Qu, Qing Yang, Shaopei Wu, Wangcai Ding, Jie Li, Guofang Li","doi":"10.1177/14613484221135866","DOIUrl":"https://doi.org/10.1177/14613484221135866","url":null,"abstract":"The precision instruments and equipment are often utilized in low-frequency and micro-amplitude vibration systems, in which many vibration isolators of rubber materials are widely used. Ignoring the low-frequency amplitude will result in errors in the fatigue life design of the vibration isolators and predicting the dynamic response of each frequency band accurately becomes necessary. However, integer-order models cannot describe the frequency dependence of rubber materials, while the fractional-order models can describe it instead. On the other hand, the elastic restoring force is strongly nonlinear under large deformation, and the vibration of the nonlinear system contains multiple harmonic components. In order to solve those issues, the fractional nonlinear Nishimura model is used to characterize the constitutive relation of vibration isolators such as air springs, which are made of carbon black filled natural rubber. The high-order harmonic balance method is used to obtain the steady-state response of the vibration system, while the fourth-order Runge–Kutta method is applied to simulate the dynamic response of the system in the low-frequency region, and the Lyapunov exponent is used to determine the stability of the system. Furthermore, the influence of parameters on the amplitude–frequency characteristics of different frequency bands is also studied, and a method to solve the optimal damping coefficient is proposed based on the primary resonance amplitude–frequency curves. The results show that there is a diversity of periodic motions in the process of adjacent super-harmonic resonance transition. Numerical simulations also demonstrate that multi-periodic motions coexist in the system. The motion transition law between the polymorphic coexistence region and its adjacent regions is summarized.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"7 1","pages":"771 - 788"},"PeriodicalIF":2.3,"publicationDate":"2022-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73279519","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}
Pub Date : 2022-12-24DOI: 10.1177/14613484221123181
S. Yabui, Hiroki Kotsuchihashi, T. Inoue
Steam turbines are used to generate thermal power in electric power plants. They are important industrial equipment that support societal infrastructure. The stable operation of steam turbines is necessary to maintain long-term electrical power supply. However, low-frequency vibration, which is referred to as steam-whirl-induced vibration, is a self-excited vibration that can damage turbines and hinders stable operation. Therefore, a prediction model and stable margin for steam-whirl-induced vibration in steam turbines should be developed. In this study, we propose a method for modeling steam-whirl-induced vibration using closed-loop system identification. This method directly creates a vibration model from the rotor displacement data. The gain, damping, and natural frequency of the vibration were calculated using this model. Moreover, an equation for the relationship between the damping and load was derived using the model, and the stable margin for increasing the load was estimated. Steam-whirl-induced vibration was modeled using the proposed method for the displacement data obtained from an actual steam turbine. The characteristics of the model are in good agreement with the experimental results, indicating the feasibility of using the model to predict steam-whirl-induced vibration.
{"title":"Analysis of low-frequency vibration in a steam turbine based on closed-loop system identification","authors":"S. Yabui, Hiroki Kotsuchihashi, T. Inoue","doi":"10.1177/14613484221123181","DOIUrl":"https://doi.org/10.1177/14613484221123181","url":null,"abstract":"Steam turbines are used to generate thermal power in electric power plants. They are important industrial equipment that support societal infrastructure. The stable operation of steam turbines is necessary to maintain long-term electrical power supply. However, low-frequency vibration, which is referred to as steam-whirl-induced vibration, is a self-excited vibration that can damage turbines and hinders stable operation. Therefore, a prediction model and stable margin for steam-whirl-induced vibration in steam turbines should be developed. In this study, we propose a method for modeling steam-whirl-induced vibration using closed-loop system identification. This method directly creates a vibration model from the rotor displacement data. The gain, damping, and natural frequency of the vibration were calculated using this model. Moreover, an equation for the relationship between the damping and load was derived using the model, and the stable margin for increasing the load was estimated. Steam-whirl-induced vibration was modeled using the proposed method for the displacement data obtained from an actual steam turbine. The characteristics of the model are in good agreement with the experimental results, indicating the feasibility of using the model to predict steam-whirl-induced vibration.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"20 1","pages":"525 - 538"},"PeriodicalIF":2.3,"publicationDate":"2022-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82363529","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}
Pub Date : 2022-12-23DOI: 10.1177/14613484221148047
Yuan Binxia, Hou Weiguang, Liu Jianben, Zhou Bing, Zhu Rui, Cao Lan
Low-frequency noise pollution in substations has a significant impact on the physical and mental health of workers. Reduction low-frequency noise pollution is an urgent problem to solve for researchers. In this paper, the different structures of Al2O3-polyurethane composites and micro-perforated plate were constructed, and the effects of cavity depth, perforated plate, and foam position on sound absorption properties were comprehensively investigated. The results showed that the position of perforated plate and the arrangement of resonance structure were the two most important factors affecting sound absorption performance. When the sound wave passed through the plexiglass plate–cavity–composites foam–perforated plate in turn, the peak position of sound absorption coefficient was located in the ultra-low frequency range. Meantime, the simulation study showed that the friction between the air column and the cavity wall in the perforated plate can consume sound energy to achieve sound absorption.
{"title":"Theoretical and experimental study on sound absorption performance of Al2O3-polyurethane foam and microperforated plate composite structure","authors":"Yuan Binxia, Hou Weiguang, Liu Jianben, Zhou Bing, Zhu Rui, Cao Lan","doi":"10.1177/14613484221148047","DOIUrl":"https://doi.org/10.1177/14613484221148047","url":null,"abstract":"Low-frequency noise pollution in substations has a significant impact on the physical and mental health of workers. Reduction low-frequency noise pollution is an urgent problem to solve for researchers. In this paper, the different structures of Al2O3-polyurethane composites and micro-perforated plate were constructed, and the effects of cavity depth, perforated plate, and foam position on sound absorption properties were comprehensively investigated. The results showed that the position of perforated plate and the arrangement of resonance structure were the two most important factors affecting sound absorption performance. When the sound wave passed through the plexiglass plate–cavity–composites foam–perforated plate in turn, the peak position of sound absorption coefficient was located in the ultra-low frequency range. Meantime, the simulation study showed that the friction between the air column and the cavity wall in the perforated plate can consume sound energy to achieve sound absorption.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"137 1","pages":"890 - 897"},"PeriodicalIF":2.3,"publicationDate":"2022-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78194090","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}
Pub Date : 2022-12-23DOI: 10.1177/14613484221148049
M. Alam, Nazmul Sharif, Md Helal Uddin Molla
Some strongly nonlinear oscillators have been investigated with the help of combined modified Lindstedt–Poincare and homotopy perturbation methods. The solutions are more accurate than those obtained by the modified Lindstedt–Poincare method. Moreover, the determination of solutions is simpler than usual homotopy perturbation methods. Some similarities and dissimilarities between the present method and other existing methods have also been discussed.
{"title":"Combination of modified Lindstedt-Poincare and homotopy perturbation methods","authors":"M. Alam, Nazmul Sharif, Md Helal Uddin Molla","doi":"10.1177/14613484221148049","DOIUrl":"https://doi.org/10.1177/14613484221148049","url":null,"abstract":"Some strongly nonlinear oscillators have been investigated with the help of combined modified Lindstedt–Poincare and homotopy perturbation methods. The solutions are more accurate than those obtained by the modified Lindstedt–Poincare method. Moreover, the determination of solutions is simpler than usual homotopy perturbation methods. Some similarities and dissimilarities between the present method and other existing methods have also been discussed.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"72 3 1","pages":"642 - 653"},"PeriodicalIF":2.3,"publicationDate":"2022-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85580836","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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