Xiaonan Zhang, You-liang Ding, Han-wei Zhao, Letian Yi
The weigh‐in‐motion (WIM) system and the structural health monitoring (SHM) system have been used as two separate modules playing different roles in bridge operation and providing different information for bridge maintenance. This study proposes a novel bridge safety condition assessment method that utilizes long‐term monitoring data from the WIM system and the SHM system. The method uses the slope of the established vehicle load and vehicle‐induced strain mapping model as the evaluation indicator for bridge condition assessment and early warning by clustering and Bayesian linear regression. The proposed method is verified with the continuous monitoring data of a concrete box girder bridge. The results show that the slope indicator of the mapping model changes with the variation of bridge performance, which is stable and can reflect the bridge state in time. The evaluation method can integrate the WIM system with the SHM system and evaluate the bridge health condition based on the correspondence between the two systems, which can make full use of the data.
{"title":"Long‐term bridge performance assessment using clustering and Bayesian linear regression for vehicle load and strain mapping model","authors":"Xiaonan Zhang, You-liang Ding, Han-wei Zhao, Letian Yi","doi":"10.1002/stc.3118","DOIUrl":"https://doi.org/10.1002/stc.3118","url":null,"abstract":"The weigh‐in‐motion (WIM) system and the structural health monitoring (SHM) system have been used as two separate modules playing different roles in bridge operation and providing different information for bridge maintenance. This study proposes a novel bridge safety condition assessment method that utilizes long‐term monitoring data from the WIM system and the SHM system. The method uses the slope of the established vehicle load and vehicle‐induced strain mapping model as the evaluation indicator for bridge condition assessment and early warning by clustering and Bayesian linear regression. The proposed method is verified with the continuous monitoring data of a concrete box girder bridge. The results show that the slope indicator of the mapping model changes with the variation of bridge performance, which is stable and can reflect the bridge state in time. The evaluation method can integrate the WIM system with the SHM system and evaluate the bridge health condition based on the correspondence between the two systems, which can make full use of the data.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88945154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Among various countermeasures for suppressing bridge stay cable vibrations, installation of external dampers near the lower cable end is the most common practice. Compared to the limitations of passive dampers, especially when attached to superlong cables, semi‐active magneto‐rheological (MR) dampers operated by smart controllers manifest superior control performance. In this study, an adaptive output‐only control scheme is proposed for cable vibration control using semi‐active MR dampers. The controller is designed based on the simple adaptive control (SAC) algorithm. Only one collocated acceleration sensor is used in the control feedback loop. The adverse effect of using acceleration feedback on the control performance is eliminated by adding a stability compensator to the SAC structure. A novel iterative process is formulated to optimize the SAC parameters. The required command voltage of MR damper for generating the control force is obtained by developing a real‐time force tracking strategy. The performance of the proposed control system is evaluated through a numerical example by inspecting the dynamic response of a full‐size stay cable when subjected consecutively to ambient excitation, wind excitation, and free vibration. The robustness of the proposed control scheme against abrupt system changes and contamination in the sensor data are investigated. Results show that the proposed control strategy can effectively mitigate cable vibration under various types of excitation. The controller is proved robust against unexpected changes in the system properties and loads, as well as the presence of sensor noise. Moreover, MR dampers are found to be effective in suppressing multimode cable vibrations.
{"title":"Semi‐active adaptive control of stay cable vibrations using MR dampers","authors":"M. Javanbakht, Shaohong Cheng, F. Ghrib","doi":"10.1002/stc.3121","DOIUrl":"https://doi.org/10.1002/stc.3121","url":null,"abstract":"Among various countermeasures for suppressing bridge stay cable vibrations, installation of external dampers near the lower cable end is the most common practice. Compared to the limitations of passive dampers, especially when attached to superlong cables, semi‐active magneto‐rheological (MR) dampers operated by smart controllers manifest superior control performance. In this study, an adaptive output‐only control scheme is proposed for cable vibration control using semi‐active MR dampers. The controller is designed based on the simple adaptive control (SAC) algorithm. Only one collocated acceleration sensor is used in the control feedback loop. The adverse effect of using acceleration feedback on the control performance is eliminated by adding a stability compensator to the SAC structure. A novel iterative process is formulated to optimize the SAC parameters. The required command voltage of MR damper for generating the control force is obtained by developing a real‐time force tracking strategy. The performance of the proposed control system is evaluated through a numerical example by inspecting the dynamic response of a full‐size stay cable when subjected consecutively to ambient excitation, wind excitation, and free vibration. The robustness of the proposed control scheme against abrupt system changes and contamination in the sensor data are investigated. Results show that the proposed control strategy can effectively mitigate cable vibration under various types of excitation. The controller is proved robust against unexpected changes in the system properties and loads, as well as the presence of sensor noise. Moreover, MR dampers are found to be effective in suppressing multimode cable vibrations.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86087933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Under the working conditions of aero‐engine, the three‐dimensional composite deformation of the blade is caused by the centrifugal force generated by high‐speed rotation and the load generated by gas scouring. Aiming at the problem of three‐dimensional composite deformation on the surface of aero‐engine blades under high‐speed rotation, a three‐dimensional deformation measurement method based on stroboscopic structure digital image correlation method is proposed, and a method for eliminating rigid body displacement induced by the trigger error of the stroboscope is proposed. First, the laser trigger‐stroboscopic irradiation system is used to freeze the high‐speed rotating blade under a specific phase. Then, the binocular vision system is used to collect the surface image of the rotating blade. Finally, the digital image correlation method is used to measure the surface deformation field of the high‐speed rotating blade. In this paper, the experimental platform is built and the displacement field and main strain field of the blade surface under high‐speed rotating state are measured. The experimental results show that the stroboscopic structure digital image correlation measurement system and method have realized displacement measurement accuracy of 2 μm and strain measurement accuracy of 100 μɛ and have realized the surface deformation measurement of the ducted turbine fan blade under the condition of 6000 rpm (CFM56‐7 engine N1 speed). The results show that the method is effective and can provide a reliable measurement method for the deformation measurement of high‐speed rotating blades in large engine manufacturing enterprises such as Aero Engine Corporation of China.
{"title":"Three‐dimensional deformation measurement of aero‐engine high‐speed rotating blade surface based on stroboscopic structure digital image correlation method","authors":"Huilin Wu, Chuanzhi Sun, Zhenjiang Yu, Yingjie Mei, Xiaoming Wang, Huiping Ma, Limin Zou, Yongmeng Liu, Jiubin Tan","doi":"10.1002/stc.3117","DOIUrl":"https://doi.org/10.1002/stc.3117","url":null,"abstract":"Under the working conditions of aero‐engine, the three‐dimensional composite deformation of the blade is caused by the centrifugal force generated by high‐speed rotation and the load generated by gas scouring. Aiming at the problem of three‐dimensional composite deformation on the surface of aero‐engine blades under high‐speed rotation, a three‐dimensional deformation measurement method based on stroboscopic structure digital image correlation method is proposed, and a method for eliminating rigid body displacement induced by the trigger error of the stroboscope is proposed. First, the laser trigger‐stroboscopic irradiation system is used to freeze the high‐speed rotating blade under a specific phase. Then, the binocular vision system is used to collect the surface image of the rotating blade. Finally, the digital image correlation method is used to measure the surface deformation field of the high‐speed rotating blade. In this paper, the experimental platform is built and the displacement field and main strain field of the blade surface under high‐speed rotating state are measured. The experimental results show that the stroboscopic structure digital image correlation measurement system and method have realized displacement measurement accuracy of 2 μm and strain measurement accuracy of 100 μɛ and have realized the surface deformation measurement of the ducted turbine fan blade under the condition of 6000 rpm (CFM56‐7 engine N1 speed). The results show that the method is effective and can provide a reliable measurement method for the deformation measurement of high‐speed rotating blades in large engine manufacturing enterprises such as Aero Engine Corporation of China.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75917971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For design of tuned mass‐damper‐inerter (TMDI) in flexible multi‐degrees‐of‐freedom (MDOF) structures, the classic 2‐DOF model is incapable of accounting for the background flexibility that comes from non‐resonant modes, leading to an unbalance in the frequency response of the flexible structure‐TMDI system. This becomes more critical for the grounded TMDI attached to a lower floor (a practical installation location). This paper proposes a set of closed‐form formulas for optimal design of the grounded TMDI based on equal modal damping principle. An analogue 2‐DOF model accounting for the background flexibility of the structure is first constructed. The root locus analysis is then performed, and three optimal frequency‐tuning formulas are derived by the equal modal damping ratio criterion corresponding to three different damping levels of TMDI. A straightforward approach for determining the optimal TMDI damping ratio is proposed based on the bifurcation point present in the root locus. All the derived optimal design formulas turn out to be dependent on the structural inherent property. The effectiveness of the proposed closed‐form formulas are assessed via both frequency‐domain and time‐history (with earthquake ground motions) analyses of a 10‐story building. Results indicate that the proposed design formulas leads to superior performance of the grounded TMDI compared to the conventional formula ignoring background flexibility. When equal modal damping of the system is guaranteed, an excellent level of vibration reduction of structural seismic responses can be achieved.
{"title":"Equal modal damping‐based optimal design of a grounded tuned mass‐damper‐inerter for flexible structures","authors":"Bei Chen, Zili Zhang, Xugang Hua","doi":"10.1002/stc.3106","DOIUrl":"https://doi.org/10.1002/stc.3106","url":null,"abstract":"For design of tuned mass‐damper‐inerter (TMDI) in flexible multi‐degrees‐of‐freedom (MDOF) structures, the classic 2‐DOF model is incapable of accounting for the background flexibility that comes from non‐resonant modes, leading to an unbalance in the frequency response of the flexible structure‐TMDI system. This becomes more critical for the grounded TMDI attached to a lower floor (a practical installation location). This paper proposes a set of closed‐form formulas for optimal design of the grounded TMDI based on equal modal damping principle. An analogue 2‐DOF model accounting for the background flexibility of the structure is first constructed. The root locus analysis is then performed, and three optimal frequency‐tuning formulas are derived by the equal modal damping ratio criterion corresponding to three different damping levels of TMDI. A straightforward approach for determining the optimal TMDI damping ratio is proposed based on the bifurcation point present in the root locus. All the derived optimal design formulas turn out to be dependent on the structural inherent property. The effectiveness of the proposed closed‐form formulas are assessed via both frequency‐domain and time‐history (with earthquake ground motions) analyses of a 10‐story building. Results indicate that the proposed design formulas leads to superior performance of the grounded TMDI compared to the conventional formula ignoring background flexibility. When equal modal damping of the system is guaranteed, an excellent level of vibration reduction of structural seismic responses can be achieved.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80488237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
System identification is primarily studied for unidirectional excitation using the Bouc–Wen model, neglecting the torsional coupling, even though real structure experiences multidirectional seismic excitation. Moreover, the high damping rubber bearings exhibit bidirectional effects, thereby requiring coupled biaxial Bouc–Wen (BBW) model and demand the estimation of model parameters for structural health monitoring. The current work presents three numerical case studies followed by experimental validation to demonstrate the applicability and efficacy of Bayesian filters named constraint unscented Kalman filter (CUKF) in identifying model parameters for the nondeteriorating system as well as deteriorating systems. With limited measurements and increased states, a two‐stage framework of the CUKF is used to enhance the performance in identifying the hysteresis parameters and system dynamics of the nondeteriorating systems. For the deteriorating system, the Paris–Erdogan law is coupled with the stiffness in the BBW model to introduce degradation as per the acceleration fatigue crack growth. The degradation parameters and deteriorating stiffness is captured through CUKF accurately. The application of CUKF to the experimental responses proves the robustness of the algorithm for coupled biaxial hysteresis system. Additionally, a unified structural health monitoring (SHM) framework is proposed for condition monitoring during extreme events and long‐term periodic maintenance through ambient vibrations. Overall, the result concludes that CUKF is a reliable Bayesian estimator for coupled biaxial hysteresis systems and demonstrates promising potential in identifying fatigue‐induced deterioration.
{"title":"Application of constrained unscented Kalman filter (CUKF) for system identification of coupled hysteresis under bidirectional excitation","authors":"Shivam Ojha, Nur M. M. Kalimullah, A. Shelke","doi":"10.1002/stc.3115","DOIUrl":"https://doi.org/10.1002/stc.3115","url":null,"abstract":"System identification is primarily studied for unidirectional excitation using the Bouc–Wen model, neglecting the torsional coupling, even though real structure experiences multidirectional seismic excitation. Moreover, the high damping rubber bearings exhibit bidirectional effects, thereby requiring coupled biaxial Bouc–Wen (BBW) model and demand the estimation of model parameters for structural health monitoring. The current work presents three numerical case studies followed by experimental validation to demonstrate the applicability and efficacy of Bayesian filters named constraint unscented Kalman filter (CUKF) in identifying model parameters for the nondeteriorating system as well as deteriorating systems. With limited measurements and increased states, a two‐stage framework of the CUKF is used to enhance the performance in identifying the hysteresis parameters and system dynamics of the nondeteriorating systems. For the deteriorating system, the Paris–Erdogan law is coupled with the stiffness in the BBW model to introduce degradation as per the acceleration fatigue crack growth. The degradation parameters and deteriorating stiffness is captured through CUKF accurately. The application of CUKF to the experimental responses proves the robustness of the algorithm for coupled biaxial hysteresis system. Additionally, a unified structural health monitoring (SHM) framework is proposed for condition monitoring during extreme events and long‐term periodic maintenance through ambient vibrations. Overall, the result concludes that CUKF is a reliable Bayesian estimator for coupled biaxial hysteresis systems and demonstrates promising potential in identifying fatigue‐induced deterioration.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73555873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nondestructive detection and sizing of internal cracks initiated in reinforced concrete have been critical problems. Geometric characterization of internal cracks and delaminations contributes to predicting their propagation path and failure pattern followed by structural prognostics. There have been limited studies on quantitative detection and characterization of vertical cracks in concrete using wave‐based NDE techniques. This study focuses on solving the problem of imaging deep internal crack planes in the concrete medium by leveraging the ultrasonic shear horizontal (SH) waves from a transducer array. Post‐processing the array full matrix capture (FMC) data with both total focusing method (TFM) and plane wave imaging (PWI) reveals their efficiency in mapping planar defects inclined between 0° and 60°. However, their performance on vertical/near‐vertical defects is found to be inferior with imaging limited to the tip of the defect planes. Further, half‐skip modes of wave dispersion have been adopted in addition to the directly scattered pulses for imaging the vertical and near‐vertical cracks. We propose an imaging framework based on the outcomes of our investigation on the best suitable methodology to detect and map planar defects like cracks inclined in the range of 0–90°. Statistical quantification of defect inclinations from the reconstructed images is compared to the ground‐truth orientations, and they are found to be 94%–99% accurate. Besides accuracy, the computational efficiency of the proposed techniques makes them desirable and reliable for quick on‐site inspections on built infrastructure.
{"title":"An ultrasonic wave‐based framework for imaging internal cracks in concrete","authors":"Sai Teja Kuchipudi, D. Ghosh","doi":"10.1002/stc.3108","DOIUrl":"https://doi.org/10.1002/stc.3108","url":null,"abstract":"Nondestructive detection and sizing of internal cracks initiated in reinforced concrete have been critical problems. Geometric characterization of internal cracks and delaminations contributes to predicting their propagation path and failure pattern followed by structural prognostics. There have been limited studies on quantitative detection and characterization of vertical cracks in concrete using wave‐based NDE techniques. This study focuses on solving the problem of imaging deep internal crack planes in the concrete medium by leveraging the ultrasonic shear horizontal (SH) waves from a transducer array. Post‐processing the array full matrix capture (FMC) data with both total focusing method (TFM) and plane wave imaging (PWI) reveals their efficiency in mapping planar defects inclined between 0° and 60°. However, their performance on vertical/near‐vertical defects is found to be inferior with imaging limited to the tip of the defect planes. Further, half‐skip modes of wave dispersion have been adopted in addition to the directly scattered pulses for imaging the vertical and near‐vertical cracks. We propose an imaging framework based on the outcomes of our investigation on the best suitable methodology to detect and map planar defects like cracks inclined in the range of 0–90°. Statistical quantification of defect inclinations from the reconstructed images is compared to the ground‐truth orientations, and they are found to be 94%–99% accurate. Besides accuracy, the computational efficiency of the proposed techniques makes them desirable and reliable for quick on‐site inspections on built infrastructure.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80073942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Actuator control plays an important role for real‐time testing based experimental techniques such as real‐time hybrid simulation (RTHS). Accurate modeling of actuator dynamics can be challenging due to the complexity and nonlinearity of the servo‐hydraulic system. In this study, nonlinear autoregressive with external input (NARX) modeling is introduced to emulate the servo‐hydraulic dynamics. The command and measured displacements of the actuator are used as input and output of the NARX model. The coefficients of the NARX model of different orders are determined online through ordinary least square regression in a real‐time manner. Data weight is further proposed to account for most recent variation in command and measured displacements. Real‐time tests with predefined random and chirp signals are conducted to evaluate the performance of proposed NARX model‐based compensation of different orders, window length, and data weight. The efficacy and robustness of proposed NARX model‐based compensation are further verified through computational simulation of a RTHS benchmark model. Both numerical simulation and laboratory experiments demonstrate that the proposed method enables effective negation of servo‐hydraulic dynamics for real‐time testing.
{"title":"Data‐driven nonlinear autoregressive with external input model‐based compensation for real‐time testing","authors":"Weijie Xu, Cheng Chen, Xiaoshu Gao, Menghui Chen, T. Guo, Chang Peng","doi":"10.1002/stc.3119","DOIUrl":"https://doi.org/10.1002/stc.3119","url":null,"abstract":"Actuator control plays an important role for real‐time testing based experimental techniques such as real‐time hybrid simulation (RTHS). Accurate modeling of actuator dynamics can be challenging due to the complexity and nonlinearity of the servo‐hydraulic system. In this study, nonlinear autoregressive with external input (NARX) modeling is introduced to emulate the servo‐hydraulic dynamics. The command and measured displacements of the actuator are used as input and output of the NARX model. The coefficients of the NARX model of different orders are determined online through ordinary least square regression in a real‐time manner. Data weight is further proposed to account for most recent variation in command and measured displacements. Real‐time tests with predefined random and chirp signals are conducted to evaluate the performance of proposed NARX model‐based compensation of different orders, window length, and data weight. The efficacy and robustness of proposed NARX model‐based compensation are further verified through computational simulation of a RTHS benchmark model. Both numerical simulation and laboratory experiments demonstrate that the proposed method enables effective negation of servo‐hydraulic dynamics for real‐time testing.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86071553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nonlinear wave mixing provides a potential method to evaluate localized micro‐damage in structures. The wave mixing technique has some unique advantages over the nonlinear ultrasonic technique based on the higher harmonic generation, such as frequency selectivity, which can separate harmonic components generated due to instrumentation. In this paper, we numerically studied the frequency mixing response induced by the nonlinear interaction of two primary Rayleigh waves in a concrete material. The nonlinearity considered in the present study is due to crack‐wave interaction, which is often called contact acoustic nonlinearity (CAN). A limited number of experimental studies were conducted on concrete prisms to evaluate surface cracks. Both numerical and experimental results illustrate the generation of the second‐ and third‐order combined harmonics, which can be utilized to detect and localize subsurface cracks in concrete structures. The newly discovered third‐order combined harmonics, which result from the mutual interaction between the primary Rayleigh waves and their induced second‐harmonic waves, can be exploited to characterize micro‐damage in various applications.
{"title":"Nonlinear ultrasonic evaluation of damaged concrete based on mixed harmonic generation","authors":"Mohammed Aslam, P. Nagarajan, Mini Remanan","doi":"10.1002/stc.3110","DOIUrl":"https://doi.org/10.1002/stc.3110","url":null,"abstract":"Nonlinear wave mixing provides a potential method to evaluate localized micro‐damage in structures. The wave mixing technique has some unique advantages over the nonlinear ultrasonic technique based on the higher harmonic generation, such as frequency selectivity, which can separate harmonic components generated due to instrumentation. In this paper, we numerically studied the frequency mixing response induced by the nonlinear interaction of two primary Rayleigh waves in a concrete material. The nonlinearity considered in the present study is due to crack‐wave interaction, which is often called contact acoustic nonlinearity (CAN). A limited number of experimental studies were conducted on concrete prisms to evaluate surface cracks. Both numerical and experimental results illustrate the generation of the second‐ and third‐order combined harmonics, which can be utilized to detect and localize subsurface cracks in concrete structures. The newly discovered third‐order combined harmonics, which result from the mutual interaction between the primary Rayleigh waves and their induced second‐harmonic waves, can be exploited to characterize micro‐damage in various applications.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81898174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the increasing use of composite materials in modern structures, the defect detection of carbon fiber‐reinforced plastics (CFRP) with ultrasonic waves is always a hot topic. Theoretical and experimental results demonstrate that the out‐of‐plane displacement of A0 mode of Lamb waves is dominant at low‐frequency ranges. Different types of defects including artificial defects, holes and cracks for flat plates, and artificial defects for a curved and stiffened (C&S)–CFRP plate are diagnosed. A shape compensatory matrix is introduced based on the symmetry of the structural features for C&S–CFRP plate. Then the statistical models of different types of defects are established and the probability‐based defect size estimation is carried out. For flat plates, the maximum relative errors are 16.3% for localization and 20.0% for size estimation. For the C&S–CFRP plate, the maximum relative errors are 11.7% for localization and 7.5% for size estimation. Therefore, a level three structural health monitoring system with defect localization and quantification functions is well‐established using PZT sensor layers.
{"title":"Localization and quantification of different types of defects in composite structures with SMART sensor layers","authors":"Xiao Liu, Xianping Zeng, Yinghong Yu, Bowen Zhao, Yishou Wang, X. Qing","doi":"10.1002/stc.3043","DOIUrl":"https://doi.org/10.1002/stc.3043","url":null,"abstract":"With the increasing use of composite materials in modern structures, the defect detection of carbon fiber‐reinforced plastics (CFRP) with ultrasonic waves is always a hot topic. Theoretical and experimental results demonstrate that the out‐of‐plane displacement of A0 mode of Lamb waves is dominant at low‐frequency ranges. Different types of defects including artificial defects, holes and cracks for flat plates, and artificial defects for a curved and stiffened (C&S)–CFRP plate are diagnosed. A shape compensatory matrix is introduced based on the symmetry of the structural features for C&S–CFRP plate. Then the statistical models of different types of defects are established and the probability‐based defect size estimation is carried out. For flat plates, the maximum relative errors are 16.3% for localization and 20.0% for size estimation. For the C&S–CFRP plate, the maximum relative errors are 11.7% for localization and 7.5% for size estimation. Therefore, a level three structural health monitoring system with defect localization and quantification functions is well‐established using PZT sensor layers.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"151 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79864590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vibrations' mitigation of linear structures, subjected to random excitations, using linear tuned mass dampers (TMDs), has been widely adopted in the field of structural dynamics. Although the TMDs are reliable and constitute a very efficient low‐cost solution, their dynamic parameters should be carefully tuned in order to guarantee optimal performances. Several optimization methods can be used such as the reliability‐based optimization (RBO) of the TMD parameters. Even though the efficiency of the RBO strategy is proven, its main drawback shows up when addressing a multi‐degree of freedom structure. Indeed, only the targeted vibrating mode exhibiting the largest amplitude is controlled whereas the other modes, with relatively smaller vibrating magnitudes, remain uncontrolled. In the present work a new band‐limited BL‐RBO criterion is presented. The new criterion is based on the evaluation of the spectral moments of the structural response, which are required for the failure probability estimation, evaluated on a limited frequency band. The efficiency of the proposed method in controlling a 20‐storey shear building subjected to a seismic excitation has been compared to others from the open literature. It has shown good capabilities in performing a multimodal control of the vibrating structure with uncertainties. The robust multimodal control has been performed using several TMDs (two TMDs per resonant mode), mounted in parallel configuration, and the obtained results showed satisfactory attenuations in the vicinity of the targeted modes.
{"title":"A band‐limited reliability‐based robust multimodal optimization of tuned mass dampers","authors":"E. Mrabet, M. H. El Ouni, N. Ben Kahla","doi":"10.1002/stc.3105","DOIUrl":"https://doi.org/10.1002/stc.3105","url":null,"abstract":"Vibrations' mitigation of linear structures, subjected to random excitations, using linear tuned mass dampers (TMDs), has been widely adopted in the field of structural dynamics. Although the TMDs are reliable and constitute a very efficient low‐cost solution, their dynamic parameters should be carefully tuned in order to guarantee optimal performances. Several optimization methods can be used such as the reliability‐based optimization (RBO) of the TMD parameters. Even though the efficiency of the RBO strategy is proven, its main drawback shows up when addressing a multi‐degree of freedom structure. Indeed, only the targeted vibrating mode exhibiting the largest amplitude is controlled whereas the other modes, with relatively smaller vibrating magnitudes, remain uncontrolled. In the present work a new band‐limited BL‐RBO criterion is presented. The new criterion is based on the evaluation of the spectral moments of the structural response, which are required for the failure probability estimation, evaluated on a limited frequency band. The efficiency of the proposed method in controlling a 20‐storey shear building subjected to a seismic excitation has been compared to others from the open literature. It has shown good capabilities in performing a multimodal control of the vibrating structure with uncertainties. The robust multimodal control has been performed using several TMDs (two TMDs per resonant mode), mounted in parallel configuration, and the obtained results showed satisfactory attenuations in the vicinity of the targeted modes.","PeriodicalId":22049,"journal":{"name":"Structural Control and Health Monitoring","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75044417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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