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11th European Workshop on Structural health monitoring, EWSHM 2024

作者： Zheng, Fei Yuan, Shenfang Qiu, Lei Ren, Yuanqiang Research Center of Structural Health Monitoring and Prognosis State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and Astronautics Nanjing China

The Guided Wave (GW)-based Multiple Signal Classification (MUSIC) method for damage imaging in composite structures offers high-resolution and flexible sensor array placement, demonstrating the considerable potential for precise damage localization. However, the application to aircraft composite structures, characterized by complex structural features, presents substantial challenges. These include pronounced anisotropy and diminished scattered signals from damaged sites. This paper presents a GW-MUSIC focusing algorithm for composite damage diagnosis. This method, designed for high localization accuracy, combines an anisotropy-compensated strategy to mitigate anisotropy while focusing on amplifying signals. Experimental validation on a composite structure demonstrated significant enhancements in localization precision, affirming the method's efficacy. © 2024 11th European Workshop on Structural health monitoring, EWSHM 2024. All rights reserved.

关键词： anisotropy compensation Composite structures damage localization GW-MUSIC focusing algorithm

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Study on Influence of Crack on the Blade Status Using FBGs

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Photonic Sensors 2018年第1期8卷 63-69页

作者： Gang XU Lei LIANG Jianzhi LI Huaping MEI Hongli LI Yijun LIU National Engineering Laboratory of Fiber Optic Sensing Technology Wuhan University of Technology Wuhan 430070 China The Key Laboratory for Health Monitoring and Control of Large Structures Shijiazhuang 050043 China School of Mechanical Engineering Hubei Engineering University Xiaogan 432000 China

The status detection for rotating parts is difficult since the sensor is influenced by the rotation in the inflammable, explosive, and strong magnetic environment. Based on the fiber Bragg grating sensing technology, this paper studies the influence of the natural frequency and deformation of a rotor blade affected by the size of crack in the blade. Test results show that the speed of the equipment and blade excited vibration frequency are two main factors or deformation and vibration frequency of the blade. With an increase in the crack depth, the blade deformation is increased while the stimulated natural frequency of the blade is decreased; at a low rotational speed, the deformation is mainly caused by the rotating speed of the blade. On the contrary, the vibration blade itself contributes to the deformation at a high speed. During the process of full speed rotation, the influence of the rotational speed on the blade deformation almost remains the same, and the influence of the natural vibration on blade deformation is increased with an increase in the rotational speed.

关键词： Rotor blade fiber Bragg grating crack depth rotational speed blade frequency blade deformation

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Probabilistic data mining for aircraft structural health monitoring 6

Probabilistic data mining for aircraft structural health mon...

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6th ECCOMAS European Conference on Computational Mechanics: Solids, structures and Coupled Problems, ECCM 2018 and 7th ECCOMAS European Conference on Computational Fluid Dynamics, ECFD 2018

作者： Yuan, Shenfang Chen, Jian Lei, Q.I.U. Research Center of Structural Health Monitoring and Prognosis State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics 29 Yudao Street Nanjing China

ISBN: (纸本)9788494731167

Structural health monitoring for aircraft structures has gradually turned from fundamental research to practical implementations. However, numerous uncertainties arise from practical engineering such as time-varying loads and boundary conditions may have great effects on sensor signals, which make it difficult for reliable evaluation of structural damages. To deal with these uncertainties, probabilistic data mining methods are attracting more and more attention and gradually applied to aircraft structural health monitoring. Probabilistic data mining methods quantify effects of these uncertainties and the damage with probabilistic models, and perform reliable damage evaluation with diagnosis method. This paper aims at discussing probabilistic data mining methods in aircraft structural health monitoring, as well as their applications to aircraft structures in practical engineering taking advantages of guided wave based structural health monitoring. copyright © Crown copyright (2018).All right reserved.

关键词： Structural health monitoring

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Using particle filtering and guided wave based structural health monitoring for on-line diagnosis and prognosis of multiple crack growth 7

Using particle filtering and guided wave based structural he...

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7th Asia-Pacific Workshop on Structural health monitoring, APWSHM 2018

作者： Chen, J. Yuan, S.F. Jin, X. Research Center of Structural Health Monitoring and Prognosis State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics 29 Yudao Street Nanjing China

ISBN: (纸本)9783000603594

Existence of multiple fatigue cracks in the same structural element is a critical problem affecting integrity and safety of engineering structures. However, reliable diagnosis and prognosis of multiple cracks is a challenge task due to uncertainties affecting crack initiation and growth from intrinsic material properties, microstructures, loading and boundary conditions. Moreover, multiple crack growth is much more complicated than a single crack due to interactions among simultaneous cracks. Consequently more uncertainties are involved. In order to deal with these uncertainties, this paper takes advantages of the guided wave based structural health monitoring (SHM) and particle filtering for online diagnosis and prognosis of multiple crack growth. The guided wave based SHM is adopted to acquire on-line measurements of simultaneous cracks. Then these measurements are sequentially input into the particle filtering framework to evaluate the posterior probability density function of crack states and model parameters for crack diagnosis and prognosis. Especially, a novel state equation is proposed for multiple crack growth in particle filtering. Validations are performed on fatigue tests of structures with hole-edge cracks. The result shows the proposed method is effective for diagnosing crack initiation and growth, as well as predicting growth of simultaneous cracks. © APWSHM 2018. All rights reserved.

关键词： Structural health monitoring

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Damage Diagnosis of Complex Connection structures of Aircraft Fuselage Stringers with Guided Wave-Based Method 14

Damage Diagnosis of Complex Connection Structures of Aircraf...

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14th International Workshop on Structural health monitoring: Designing SHM for Sustainability, Maintainability, and Reliability, IWSHM 2023

作者： Xu, Yusen Chen, Jian Yuan, Shenfang Yang, Yahui Qin, Zhen Research Center of Structural Health Monitoring and Prognosis State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and Astronautics 29 Yudao Street Nanjing210016 China

ISBN: (纸本)9781605956930

For civil aircraft, structural forms of its components like fuselage and wing are very complicated. Usually, these structural components are manufactured separately and then riveted together. These connection parts, such as stringer joints and skin lap joints, are prone to be cracked and failure. In addition, most structures are inaccessible, making manual maintenance difficult. Therefore, it is of great significance to reliably monitor the fatigue crack damage of complex connection structures. Guided wave (GW) based structural health monitoring (SHM) has attracted wide attention in the aerospace field since it has the characteristics of being sensitive to small damages, and capable of monitoring large areas. However, the complex configuration, the limited space, and the interference of bolts and rivets make sensor deployment difficult. Moreover, during propagation in complex connection structures, guided waves will undergo reflection, transmission, and mode conversion, resulting in mode aliasing and wave packet deformation of response guided wave signals. The structural damage information contained in the signal will also be masked, which brings difficulties to crack monitoring in complex connection structures. Although there have been some related studies on crack monitoring of metal joint structures such as lap joints, there are still other parts in the complex joint structure of the actual fuselage, such as long stringers and belt plates. At present, especially for the multi-layer riveted butt joint structure with stringers, the research is still very limited. In this paper, the amplitude and mode of the guided wave signals of different types of channels between the components of the single strap butt joint structure with stringer are analyzed. By imposing simulated damage, the effect of the damage scattering signal on the damage identification ability after guided waves pass through multiple rivet holes or multi-layer structures of the complex structure is stud

关键词： Guided electromagnetic wave propagation

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Main Structure Design and Constructional Safety control of large-span Gravel Surrounding-Rock Tunnel

Main Structure Design and Constructional Safety Control of L...

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作者： Li De-kang Li Hao-ran OuYang Zuo-lin Yue Zhi-guo Dong Yan-dong Structural Health Monitoring and Control Institute Shijiazhuang Tiedao University The Key Laboratory for Health Monitoring and Control of Large Structures Shijiazhuang Tiedao University Shuohuang Railway Development Limited Liability Company

As the construction of large-span gravel surrounding-rock tunnel is very difficult which has serious security risks,it is significant to choose a set of reasonable structure design methods and safety control *** paper taked a large-span gravel road tunnel in Jinan Expressway as an *** combining theoretical analysis with numerical simulation,the main structure design process of the large-span IV level surrounding-rock tunnel was divided into four steps,meanwhile concrete measure basis and testing methods were *** to the engineering geological conditions and the structure design schemes,the construction schemes and monitoring measurement projects of large-span gravel surrounding-rock tunnel were determined to ensure the safety of tunnel *** paper provides a complete example scheme for the design and construction of the main structure of the large-span IV class surrounding-rock tunnel,which provides a reference for similar projects in the future.

关键词： IOP Main Structure Design and Constructional Safety control of large-span Gravel Surrounding-Rock Tunnel

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Effects of the reattachment on dry galloping in the critical Reynolds number range 9

Effects of the reattachment on dry galloping in the critical...

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9th Asia Pacific Conference on Wind Engineering, APCWE 2017

作者： Ma, Wenyong Liu, Qingkuan Liu, Xiaobing Key Laboratory for Health Monitoring and Control of Large Structure Shijiazhuang Tiedao University Hebei province China Department of Wind Science and Engineering Shijiazhuang Tiedao University Shijiazhuang City Hebei Province China

large amplitude vibrations of circular cylinders in the critical Reynolds number range are reproduced in wind tunnels. Displacements and wind pressure for the cylinders are measured synchronously to reveal the characteristics of aerodynamic force for the vibrating cylinders in a Reynolds number range where flow re-attaches on the rear of the cylinder. Effects of these reattachments on the aerodynamic forces and the vibrations are discussed. The results show that the reattachment can produce unsteady aerodynamic force and excite large amplitude vibration when it forms unstable separation bubble at the early critical Reynolds number range. Once it develops stable separation bubble, the reattachment mitigates the vibrations by creating strong negative aerodynamic damping. © 9th Asia Pacific Conference on Wind Engineering, APCWE 2017. All Rights Reserved.

关键词： Circular cylinders

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THE INTERNAL CRACK IN PIEZOELECTRICPIEZOMAGNETIC SANDWICHED STRUCTURE UNDER IN-PLANE COUPLE LOADING

THE INTERNAL CRACK IN PIEZOELECTRICPIEZOMAGNETIC SANDWICHED ...

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2016年全国压电和声波理论及器件应用研讨会

作者： Xing ZHAO Jin-xi LIU Zheng-hua QIAN Department of Engineering Mechanics/The Key Laboratory for Health Monitoring and Control of Large Structures Shijiazhuang Tiedao University State Key Laboratory of Mechanics and Control of Mechanical Structures/College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

Background, Motivation and Objective The piezoelectric-piezomagnetic(PE-PM) sandwiched structures are consisted of layered piezoelectric and piezomagnetic materials. They are easy to be manufactured and possess superior magnetoelectric(ME) coupling effect. With these superiorities, the PE-PM sandwiched structures have been widely used in sensors, transducers and acoustic wave devices and so on. However, due to the fragility of the materials and complicated in-service loading conditions, the PE-PM sandwiched structures tend to fracture easily. So, it is essential to research the internal crack in PE-PM sandwiched structures under electro-magneto-mechanical coupled loadings. However, up until now, there is no paper studies the mode-I crack in PE-PM-PE sandwiched structure under in-plane electro-mechanical coupled loading. From the above, considering the magnetic field of piezoelectric material and the electric field of piezomagnetic material, a mode-I internal crack problem of a PM layer bonded to two PE layers is studied in this paper. Statement of Contribution/Methods This paper contributes to obtaining an analytical solution by using the integral transform technique. Firstly, the Fourier transforms are applied to the governing equations, and a set of appropriate solutions are obtained with some unknown functions. Then, substituting the appropriate solutions into boundary conditions meanwhile considering the magnetoelectric permeable crack plane conditions, we could derive the dual integral equations after the complex mathematical process. In order to obtain the magneto-electro-elastic field in the near of the crack tip, the dual integral equations are reduced into the singular integral equations with Cauchy kernel of the second kind. Finally, the Cauchy singular integral equations will be solved by Gauss-Jacobi collocation method. Meanwhile, the field intensity factors(FIFs) could be obtained. Results In this paper, an integral transform technique is employed to re

关键词： Mode I crack Piezoelectric-piezomagnetic sandwiched structure Field intensity factors Cauchy singular integral equation

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Multi-block SSD based on small object detection for UAV railway scene surveillance

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Chinese Journal of Aeronautics 2020年第6期33卷 1747-1755页

作者： Yundong LI Han DONG Hongguang LI Xueyan ZHANG Baochang ZHANG Zhifeng XIAO North China University of Technology Beijing 100144China Key Laboratory of Large Structure Health Monitoring and Control Shijiazhuang 050043China Unmanned System Research Institute Beihang UniversityBeijing 100083China Guangdong Provincial Key Laboratory of Computer Vision and Virtual Reality Technology Shenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China State Key Laboratory of Information Engineering in Surveying Wuhan UniversityWuhan 430079China

A method of multi-block Single Shot Multi Box Detector(SSD)based on small object detection is proposed to the railway scene of unmanned aerial vehicle *** address the limitation of small object detection,a multi-block SSD mechanism,which consists of three steps,is ***,the original input images are segmented into several overlapped ***,each patch is separately fed into an SSD to detect the ***,the patches are merged together through two *** the first stage,the truncated object of the sub-layer detection result is *** the second stage,a sub-layer suppression and filtering algorithm applying the concept of non-maximum suppression is utilized to remove the overlapped boxes of *** boxes that are not detected in the main-layer are *** addition,no sufficient labeled training samples of railway circumstance are available,thereby hindering the deployment of SSD.A two-stage training strategy leveraging to transfer learning is adopted to solve this *** deep learning model is preliminarily trained using labeled data of numerous auxiliaries,and then it is refined using only a few samples of railway scene.A railway spot in China,which is easily damaged by landslides,is investigated as a case *** results show that the proposed multi-block SSD method produces an overall accuracy of 96.6%and obtains an improvement of up to 9.2%compared with the traditional SSD.

关键词： Deep learning Multi-block Single Shot MultiBox Detector(SSD) Objection detection Railway scene Unmanned aerial vehicle remote sensing

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Mechanical and Failure Characteristics of Shear keys on Immersed Tunnel Segment Joints under Differential Settlements

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Procedia Engineering 2016年 166卷 373-378页

作者： Zhi-nan Hu Yong-li Xie School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang 050043 China The Key Laboratory for Health Monitoring and Control of Large Structures Shijiazhuang 050043 China College of Highway Chang’an University Xi’an 710064 China

In order to research mechanical and failure characteristics of shear keys on immersed tunnel segment joints, a 1:4.69 large scale immersed tunnel physical model test was conducted on a settlement platform. Bending and twisting working conditions of segment joints caused by uneven settlements and uneven back-silting were simulated, by means of controlling the lifting jacks under the settlement platform. Simultaneously, a 3-D numerical simulation which considered the nonlinearity of rubber pads and contacting effects between segment joints was carried out. The results shows that vertical shear keys have main contribution to resist expansion of segment joints in bending condition, and vertical shear keys on the soft layer have larger shear forces than that on the hard layer. In addition, shear stresses were mainly concentrated at the terminal corners and connecting corners between shear keys and segments. Correspondingly, at the terminal corners and connecting corners between shear key and segments appeared 30° ∼60° and 45° extending cracks respectively. At last, some structural strengthen suggestions on shear keys were offered for immersed tunnel design.

关键词： Immersed tunnel Segment joints Shear keys Failure characteristics Differential settlements

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