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14th International Conference on Fracture, ICF 2017

作者： Yuan, H. Han, J. MOE Key Laboratory of Disaster Forecast and Control in Engineering Institute of Applied Mechanics Jinan University Guangzhou510632 China

Pipe structure is a very important structural form for modern industry. The limitations of the overall system performance usually come from the capacity of pipe joints. Therefore, a cohesive interface modeling approach to debonding analysis of adhesively bonded pipe joints is presented in this paper. An analytical solution for the full-range behavior of an adhesively bonded pipe joint under combined thermal and mechanical loadings is obtained, assuming that the bond interface follows a bi-linear bond-slip model. The analytical solutions compared with finite element results can be used to explain the load-displacement relationship, stress transfer mechanism and the interface crack propagation. © 2017 Chinese Society of Theoretical and Applied Mechanics. All Rights Reserved.

关键词： Adhesives

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Application of sparsity in structural damage detection 8

Application of sparsity in structural damage detection

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8th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2017

作者： Chen, Z.P. Yu, L. School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9781925553055

Structural damage detection (SDD) is one of the major subjects in the field of structural health monitoring (SHM) and various methodologies have been proposed and achieved great accuracy in such field. Inspired by the concept of sparsity, applications of sparsity in SDD are explored in this paper. First of all, an adaptive dictionary is proposed based on intrinsic mode function (IMF), which is utilized to reconstruct compressed acceleration excited by random load. The compressed accelerations are acquired under the application of compressive sensing (CS) technique. Then, as structural damages generally appear locally, SDD problem is characterized by sparsity. Sparse regularization technique is employed to solve SDD by defining two objective functions, to which different sparsity penalty items are introduced. Two iteration procedures inspired by Newton-Gauss algorithm are also presented to solve the problem. Simply-supported beam with different damage degrees are taken as numerical simulations example. The illustrated results show that the proposed method can give an accurate SDD and is robustness to noise. Some related issues are discussed as well. © 2017 International Society for Structural Health Monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Structural health monitoring

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Output-only structural damage detection based on hard-threshold method: Theoretical study 8

Output-only structural damage detection based on hard-thresh...

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8th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2017

作者： Pan, C.D. Yu, L. School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9781925553055

Structural damage detection (SDD) with a vehicle-bridge system has been widely studied, since traffic excitations contribute to live load components in bridge design code. As an attempt work, this paper aims to propose an output-only SDD method based on hard-threshold strategy with unknown moving forces. Firstly, a transfer matrix is formulated between any two sensors for a healthy bridge structure. Singular value decomposition (SVD) technology is performed for the transfer matrix, and the corresponding singular vectors are used for decomposing two measured responses based on hard-threshold method. Then the decomposed results are used for estimating some singular values. Finally, a damage indicator (DI), which is defined for classifying status of structures, is calculated by comparing the differences between the estimated and true singular values. In order to assess the accuracy and feasibility of the proposed method, a simply-supported bridge subjected to one moving force is taken as an example for numerical simulations. The illustrated results show that the proposed method has a potential ability for solving the SDD problem. Some drawbacks of the proposed method are also discussed as well. © 2017 International Society for Structural Health Monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Singular value decomposition

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Identification of moving vehicle forces on bridge structures via moving average Tikhonov regularization

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SMART MATERIALS AND STRUCTURES 2017年第8期26卷

作者： Pan, Chu-Dong Yu, Ling Liu, Huan-Lin Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Guangdong Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

Traffic-induced moving force identification (MFI) is a typical inverse problem in the field of bridge structural health monitoring. Lots of regularization-based methods have been proposed for MFI. However, the MFI accuracy obtained from the existing methods is low when the moving forces enter into and exit a bridge deck due to low sensitivity of structural responses to the forces at these zones. To overcome this shortcoming, a novel moving average Tikhonov regularization method is proposed for MFI by combining with the moving average concepts. Firstly, the bridge-vehicle interaction moving force is assumed as a discrete finite signal with stable average value (DFS-SAV). Secondly, the reasonable signal feature of DFS-SAV is quantified and introduced for improving the penalty function (||x||(2)(2)) defined in the classical Tikhonov regularization. Then, a feasible two-step strategy is proposed for selecting regularization parameter and balance coefficient defined in the improved penalty function. Finally, both numerical simulations on a simply-supported beam and laboratory experiments on a hollow tube beam are performed for assessing the accuracy and the feasibility of the proposed method. The illustrated results show that the moving forces can be accurately identified with a strong robustness. Some related issues, such as selection of moving window length, effect of different penalty functions, and effect of different car speeds, are discussed as well.

关键词： moving force identification (MFI) regularization method moving average structural health monitoring (SHM)

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RIP-based subspace projection method for structural damage detection 8

RIP-based subspace projection method for structural damage d...

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8th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2017

作者： Luo, Z.W. Yu, L. School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9781925553055

Structural damage detection (SDD) of large span structures needs to deal with a large number of data produced by thousands of sensors. SDD costs vast amounts of calculating time in a structural health monitoring (SHM) system. To overcome this problem, a new method of SDD is proposed in this paper. A measurement matrix satisfying restricted isometry property (RIP) is used to reduce the numbers of sensitivity equation. It projects the sensitivity matrix into the subspace. In the meantime, it also projects the differences of modal parameters between damaged and undamaged structure into this subspace and reduces the dimensions of differences of modal parameters. Then, the information in lower dimensions can be used for SDD. Finally, due to the sparsity of damage coefficients, sparse regularization method can be used to solve the sensitivity equation in subspace and improve the ill-posedness of SDD. In order to assess capabilities of the proposed method, a plane truss is taken as an example for numerical simulations. Different damage scenarios and the effects of measurement noises on the proposed method are considered. The illustrated results show that the proposed method can effectively detect damage location(s) and quantify damage degrees. © 2017 International Society for Structural Health Monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Matrix algebra

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Constructing explicit homoclinic solution of oscillators: An improvement for perturbation procedure based on nonlinear time transformation

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COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION 2017年 48卷 123-139页

作者： Chen, Y. Y. Chen, S. H. Zhao, W. Guangzhou Univ Key Lab Vibrat Control & Struct Safety Guangzhou 510405 Peoples R China Sun Yat Sen Univ Dept Appl Mech & Engn Guangzhou 510275 Peoples R China Jinan Univ Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

An improved procedure for perturbation method is presented for constructing homoclinic solutions of strongly nonlinear self-excited oscillators. Compared with current perturbation methods based on nonlinear time transformations, the preference of the present method is that the explicit solutions, in respect to the original time variable, can be derived. In the paper, the equivalence and unified perturbation procedure with nonlinear time transformations, by which implicit solutions can be derived at nonlinear time scales, are firstly presented. Then an explicit generating homoclinic solution for power-law strongly nonlinear oscillator is derived with proposed hyperbolic function balance procedure. An approximation scheme is presented to improve the perturbation procedure and the explicit expression for nonlinear time transformation can be achieved. Applications and comparisons with other methods are performed to assess the advantage of the present method.(C) 2016 Elsevier B.V. All rights reserved.

关键词： Explicit solution Homoclinic solution Perturbation method Nonlinear time transformation

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Mechanism and control of spalling for friable sandstone pillars in a room and pillar mine

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Journal of engineering Science and Technology Review 2018年第6期11卷 197-205页

作者： Ziwei, Ding Jindui, Jia Amirhossein, Bagherieh Ji, Li Yue, Song School of Energy Xi'an University of Science and Technology Xi'an710054 China Anhui Province Key Lab. of Mining Response and Disaster Prevention Control in Deep Coal Mine Anhui University of Science and Technology Huainan232001 China Department of Mineral engineering New Mexico Institute of Mining and Technology SocorroNM87801 United States

The ability to efficiently control sandstone pillar spalling is extremely important in ensuring the safety and highefficiency production of sandstone mines. The increase in size is usually suggested as a remedy for pillar spalling, but none of the suggested remedies reflect the influences of geotechnical properties of rock mass on stability control. Some sandstone mining practices have proven that increasing the size of pillars cannot effectively control pillar spalling. The relationship between the strength of St. Peter sandstone pillar and pillar loads was theoretically analyzed in the current study, in order to examine the influences of geotechnical parameters of sandstone on the stability of pillars and control pillar spalling. The key geotechnical parameters that influence the stability of sandstone pillars were also examined. Subsequently, the pillar instability mechanism and influences of geotechnical parameters on pillar stability were investigated by Finite Difference Method. Finally, a ground control method using shotcrete on pillar was proposed for increasing the stability of pillars. Results demonstrate that compressive stress on the St. Peter sandstone pillar is considerably larger than the compressive strength after mining, resulting in the evident deformation of most regions. The relation curves of displacement at the pillar top with internal friction angle and cohesion are in the power functional distributions, but the change of cohesion is more significant in the pillar strength. The displacement at the pillar top gradually decreases with the increase in internal friction angle, whereas the plastic failure regions of pillars gradually decrease from the bottom to the upper parts with the increase in cohesion. A field industrial test proves that shotcrete on pillars can increase pillar strength, which effectively controls the pillar spalling. Research results provide theoretical and practical guidelines to enhance the stability of pillars under the sa

关键词： Rock mechanics

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A Model-Based Unloaded Test Method for Analysis of Braking Capacity of Elevator Brake

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ADVANCES IN MATERIALS SCIENCE AND engineering 2018年第1期2018卷 1-10页

作者： Peng, Qifeng Li, Zhongxing Yuan, Hong Huang, Guojian Li, Shanqing Sun, Xueli Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Guangzhou Acad Special Equipment Inspect & Testin Guangzhou 510180 Guangdong Peoples R China

In order to improve the inspection efficiency and accuracy of the braking capacity of the elevator brake being used, a novel method for analyzing the full-loaded braking performance by using the unloaded braking performance is proposed, and a set of methods for measuring the braking torque is designed. Based on the analysis of the key factors that affect the mechanical performance of the elevator brake, the calculation model of the braking torque in the process of the emergency braking with the traction ratio of 2 : 1 is established, and the relationship between the braking torque and acceleration under different working conditions is analyzed. It is shown that, for the model assumed, the emergency braking torque is 1.56 times that of the static braking torque under 1.25 times the rated load. The braking torque increases linearly with the increase of braking acceleration. An elevator model being used is tested and calculated. The experimental results show that the braking acceleration measured by the experiment is 11.95% less than the theoretical value. And the analysis shows that, comparing with the traditional test method, the braking torque test method designed in this paper is more accurate and safe.

关键词： BRAKES ELEVATORS ACCURACY TRACTION (engineering) ACCELERATION (Mechanics)

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Simultaneous identification of moving forces and structural damages by L1/2 regularization method 24th

Simultaneous identification of moving forces and structural ...

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24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2016

作者： Pan, Chudong Yu, Ling Department of Mechanics and Civil Engineering Jinan University Guangzhou China MOE Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangzhou China

ISBN: (纸本)9781138029934

Moving Force Identification (MFI) and Structural Damage Detection (SDD) are two important issues in the field of bridge Structural Health Monitoring (SHM). Based on sparse regularization L1/2 optimization techniques, a novel MFI-SDD method is proposed for identifying both moving forces and structural damages by using structural responses only. First of all, some measurement sensors in a structure can be divided into two sets. The relationship between them can be expressed by transmissibility concept. With a given damage vector, structural responses can be rebuilt by using transmissibility matrix. The SDD process is to find possible damages which make the difference between measured and rebuilt responses minimum. The L1/2 regularization is added to acquire a sparse damage vector. Secondly, the moving forces can be identified by Tikhonov regularization method with the SDD results. In order to assess accuracy and feasibility of the proposed method, a damaged simply-supported beam bridge subjected to moving forces is taken as an example for numerical simulations. The illustrated results show that the proposed method can simultaneously identify both moving forces and structural damages with a good accuracy and better robustness to noise. Some related issues are discussed as well. © 2017 Taylor & Francis Group, London.

关键词： Structural health monitoring

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Research on pipeline chaos detection based on ultrasonic guided wave 24th

Research on pipeline chaos detection based on ultrasonic gui...

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24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2016

作者： Wen, Yuli Ma, Hongwei College of Science and Engineer Jinan University Guangzhou China Key Lab of Disaster Forecast and Control in Engineering Ministry of Education Guangzhou China School of Civil Engineering Qinghai University Xining China

ISBN: (纸本)9781138029934

This article presents a study on weak ultrasonic guided waves signal processing. In long range detection or small defect detection, the defect echo often shows the characteristic of weak signal because of attenuation, which becomes the main obstacles of ultrasonic guided waves detection. Due to the sensitive dependence on initial condition and strong noise immunity of chaotic system, Duffing chaotic oscillator weak signal detection method based on ultrasonic guided wave has been proposed. When the critical chaotic system detect the weak signal, the system state will be change. The parameters of chaotic system was determined according to the ultrasonic guided wave detection. The maximum Lyapunov exponent is chosen to detect the system state change. The chaotic oscillator is proved to have good immunity to noise by using chaotic system to process different amplitudes of Gaussian white noise. Four kinds of section reduction ratio defects are analyzed respectively. The method has been verified to be useful to expand range and improve the sensitivity in pipes defect detection by the results of numerical simulations and experiments on 6 meters pipeline. © 2017 Taylor & Francis Group, London.

关键词： Chaotic systems

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