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Structural damage detection using relationship between transmissibility functions and stiffness variations 9

Structural damage detection using relationship between trans...

9th International Conference on Structural Health Monitoring of Intelligent Infrastructure: Transferring Research into Practice, SHMII 2019

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

Structural damage detection (SDD), as one of the most challenging issues in the field of structural health monitoring (SHM), has been extensively studied in recent years. A lot of methodologies have been proposed for effective SDD. However, in most cases, only structural responses, e.g. accelerations, can be easily measured in practical engineering, which limits the application of numerous SDD algorithms. In this study, a novel SDD method is proposed for damage localization and quantification by means of a newly deduced relationship between transmissibility functions (TFs) and stiffness variations. First, a finite element (FE) model is developed for a real structure, and only stiffness variations are esteemed when structural damages occur in the structure. As a ratio between frequency response functions of structural responses, the TFs are used to detect damages by using structural responses only. Moreover, as prior information, the sparsity of structural damages is introduced and the sparse regularization is employed to improve the reasonability of SDD results. Finally, numerical simulations on damages in a simply-supported beam are conducted to assess the performance of the proposed SDD method. The illustrated SDD results show that the proposed method can effectively locate structural damages and quantify damage severities with a good robustness to measurement noises. Copyright © SHMII 2019. All rights reserved.

关键词： Structural health monitoring

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Online structural damage detection based on online dictionary learning 9

Online structural damage detection based on online dictionar...

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9th International Conference on Structural Health Monitoring of Intelligent Infrastructure: Transferring Research into Practice, SHMII 2019

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

In order to detect the variation of stiffness in structures, an online structural damage detection (SDD) method is proposed based on online dictionary learning (ODL) in this paper. The acceleration responses of structures are measured as training data to determine an adaptive dictionary which gives sparse representation for the acceleration responses. In the process of ODL, the dictionary is able to be determined in an iterative manner, which means that the dynamically changing data can be used to update the dictionary sequentially. Then, the mean sparsity (MS) is applied as a damage-sensitive index to indicate the occurrence of damage, which therefore formulates a framework to identify structural damage instantaneously. The accuracy of SDD results is investigated based on the proposed online SDD algorithm under random load. Numerical simulations on structural damages of a simply-supported beam are conducted and the SDD results illustrate the effectiveness of the proposed methods for determining whether and when damage emerges. Moreover, as the proposed method is adaptive and model-free method, it provides a wide application prospect in online SDD of real structures. Copyright © SHMII 2019. All rights reserved.

关键词： Structural health monitoring

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Microstructure, Wear and Friction Behavior of Cocraltay-Xcnts Composite Coatings Deposited by Laser-Induction Hybrid Cladding

SSRN

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SSRN 2022年

作者： Zhou, Shenfeng Tingjin, Xie Rui, Zhang Yanliang, Yi Institute of Advance Wear & Corrosion Resistant and Functional Materials Jinan University Guangdong Guangzhou510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China Laser Technology Institute School of Physical science and Technology Tianjin University of Technology Tianjin300387 China Shaoguan Research Institute of Jinan University 168 Muxi Avenue Shaoguan512027 China

Through this design, partial CNTs occur chemical reactions to create a reinforcement phase, while the other CNTs can be retained as lubrication phase. The MCrAlYTa-xCNTs (x=0,1,2,and 4 wt%) composite coatings were prepared by laser-induction hybrid cladding (LIHC). And the microstructure, hardness, and wear behaviour of coating were systematacially analyzed. Results show that the composite coatings are mainly composed of TaC, γ-(Co,Cr) and β-(Co,Cr)Al. With the increase of CNTs content, the volume fraction of TaC increases from 13.11 vol% to 16.12 vol%. Meanwhile, the nanohardnesses of γ-(Co,Cr) and β-(Co,Cr)Al are improved from 7.49 GPa to 9.36 GPa and 9.72 GPa to 11.19 GPa, respectively. As a result, the microhardness of coating increases from 536.25 HV to 738.16 HV, the wear rate decreases from 32.4×10-3 mg·m-1 to 6.1×10-3 mg·m-1, and the average friction coefficient decreases from 0.55 to 0.44. The good wear performance of the coating is attributed to the increased TaC and the CNTs lubricant film. © 2022, The Authors. All rights reserved.

关键词： Carbon nanotubes

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Three-body problem – from Newton to supercomputer plus machine learning

arXiv

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arXiv 2021年

作者： Liao, Shijun Li, Xiaoming Yang, Yu State Key Lab of Ocean Engineering Shanghai200240 China Center of Marine Numerical Experiment School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai200240 China School of Physics and Astronomy Shanghai Jiaotong University Shanghai200240 China School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China MOE Key Laboratory of Disaster Forecast and Control in Engineering Guangzhou510632 China

The famous three-body problem can be traced back to Newton in 1687, but quite few families of periodic orbits were found in 300 years thereafter. In this paper, we propose an effective approach and roadmap to numerically gain planar periodic orbits of three-body systems with arbitrary masses by means of machine learning based on an artificial neural network (ANN) model. Given any a known periodic orbit as a starting point, this approach can provide more and more periodic orbits (of the same family name) with variable masses, while the mass domain having periodic orbits becomes larger and larger, and the ANN model becomes wiser and wiser. Finally we have an ANN model trained by means of all obtained periodic orbits of the same family, which provides a convenient way to give accurate enough predictions of periodic orbits with arbitrary masses for physicists and astronomers. It suggests that the high-performance computer and artificial intelligence (including machine learning) should be the key to gain periodic orbits of the famous three-body problem. © 2021, CC BY.

关键词： Supercomputers

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Gas Drainage Methods and Developing Direction of Gob

Gas Drainage Methods and Developing Direction of Gob

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作者： YAN Bao-yong CAO Liu Chongqing Research Institute of China Coal Technology and Engineering Group State Key Lab. of Gas Disaster Monitoring and Control as well as Emergency Technology Southwest Petroleum University

In the coal mine gas drainage,the gas drainage in gob has a dominant position. According to different stages of the production,the mining areas are divided into the gob,the old one and the abandoned one. Gas drainage of gob has an important influence on mining propulsion. Through comparative analysis of various drainage methods,exclusive tunnel pumping method will gradually be eliminated with the promotion of directional drilling technique in the roof construction and application. Large diameter roof horizontal directional long drill hole will replace the roof pumping lane,the roof short drilling,and gob buried drainage pipe. Some old gob has begun experiments of ground wells. A well used repeatedly can maximize the drainage of gas in the future,along with one-well three-purpose technology continues to be mature. The true sense of the abandoned mine gas drainage is still blank in China,according to the experience of foreign pumping,the ground large diameter bored construction will become a reasonable choice in obsolete mine gob gas drainage.

关键词： gob gas drainage ground borehole

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Transient Analysis Based on Finite Element Method for Ball Grid Array Package

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IOP Conference Series: Earth and Environmental Science 2021年第4期769卷

作者： Wenhao Luo Wei Su Xianshan Dong Zhenhua Nie Agam Tomar MOE Key lab of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou China MOE Key lab of Disaster Forecast and Control in Engineering Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key lab of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia MOE Key lab of Disaster Forecast and Control in Engineering Perth Australia

In this paper, finite element simulation is carried out for BGA sample. The authors establishes the model of fixture, ceramic panel and metal sheet. Based on this model, several layers papers are laid on the metal sheet for simulation test. Then, ANASYS Workbench is used to conduct transient analysis of the samples to study the influence of different thickness papers on acceleration and time. The results provide useful reference for the adjustment of dynamic response parameters.

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Study on the optimum position of gas extraction in goaf of high position borehole based on CFD 7

Study on the optimum position of gas extraction in goaf of h...

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7th International Symposium on Project Management, ISPM 2019

作者： Yan, Baoyong Zhang, Xiaoze Li, Yibin Chongqing Research Institute of China Coal Technology and Engineering Group Chongqing400039 China State Key Lab. of Gas Disaster Monitoring and Control as well as Emergency Technology Chongqing400039 China College of Energy and Power Engineering Lanzhou University of Technology Lanzhou730050 China

ISBN: (纸本)9781921712692

In order to study the effect of gas extraction by high position borehole in goaf, and determine the best position of the borehole, it provides a reference for the selection of gas extraction target location by high position borehole in the future. Based on the goaf of 40113 working face of a mine in Fenxi Group of Shanxi Province, the gas migration model is established. and the gas extraction effect of high position borehole under different target strata is simulated by FLUENT. The results show that the gas concentration in the upper corner of the working face is reduced from 2.3% to 0.7% after using high position borehole to extract gas by compared with the non-extraction situation, which solves the problem of gas concentration exceeding the limit in the upper corner of the working face. When high position borehole of the distance from the floor of goaf is 26m,and the distance from the level of return air roadway is 25m, the gas concentration in the upper corner of the working face is 0.58%, and the gas concentration in the hole is the highest and the purity is the largest. © 2019 by Aussino Academic Publishing House.

关键词： Extraction

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A novel MOALO-based algorithm for structural damage detection 7

A novel MOALO-based algorithm for structural damage detectio...

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7th Asia-Pacific Workshop on Structural Health Monitoring, APWSHM 2018

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

ISBN: (纸本)9783000603594

Structural damage detection (SDD) is the first-type inverse problem in structural dynamics, and it is usually converted to a kind of constrained optimization problem in mathematics. Exploring a highly accurate and robust solution to the SDD problem is a challenging task in the field of structural health monitoring (SHM). In this study, a novel SDD method is proposed based on multi-objective ant lion optimizer (MOALO) algorithm, in which multi-objective functions are defined for the typical SDD inverse problem based on the model updating theory. The modal parameters, such as natural frequencies and mode shapes, are adopted into the objective functions whilst considering weighted coefficients corresponding to different modal parameters at the same time. The weighted strategy and sparse regularization are also taken into consideration for accurate SDD results with good robustness to noise. All illustrated results show that the proposed MOALO method is able to accurately locate and quantify damage of structures, which provides a potential SDD tool for real structures onsite. © APWSHM 2018. All rights reserved.

关键词： Inverse problems

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Application of Matlab.to Data Processing of Buckling Experiments

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IOP Conference Series: Materials Science and engineering 2020年第1期746卷

作者： Jiahui Zhou Peng Yang Jie Sun Chenyu Shi Jianghong Xue School of Mechanics and Construction Engineering Jinan University Key Lab of Disaster Forecast and Control in Engineering Ministry of Education Guangzhou 510632 Guangdong China

In this paper, matlab.programs were written to efficiently process the experiment data for buckling and post-buckling of delaminated composite beams. In the experiments, data collected from 810 Material Test System (MTS) and from dial indicator were sampled at different frequencies, thus were not matched with each other in time. To solve this problem matlab.programs were developed. It shows that using the developed program, the experiment data from the two testing systems are corresponding and truly reflect the changes of mechanical parameters in the buckling and post-buckling process of specimens in the experiments.

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Experimental study on the energy absorption characteristics of viscoelastic damping layers

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IOP Conference Series: Earth and Environmental Science 2021年第2期861卷

作者： Xiancheng Mei Qian Sheng Zhen Cui Qingzi Luo Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China University of Chinese Academy of Sciences Beijing 100049 China School of Civil and Transportation Engineering Guangdong University of Technology Guangzhou 510006 MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou 510632

This work aims to further promote the research and development of flexible damping technology for the seismic damage control of underground engineering structures. On the basis of the understanding of the application of viscoelastic damping theory to the field of earthquake resistance of bridge buildings, impact tests on different rock damping layer– concrete specimens are conducted using the improved split Hopkinson pressure bar test system to analyze the energy absorption characteristics of the viscoelastic damping layers. A comparative analysis of the test results is also performed to differentiate the laws of energy absorption of the viscoelastic damping layer structure using different damping layer materials (rubber and silicone) and different damping layer shapes (honeycomb, corrugated, and cylindrical). Given damping layers with the same material and structure, the energy absorption laws of the structures with different damping layer thicknesses are compared and analyzed. The optimal thickness of the damping layers is also discussed. Results show that the incident energy absorbed by the damping layers of different materials increases by more than 10% relative to the control group (rock–concrete specimen). Such an increase indicates that the structures have superior energy absorption characteristics and that the rubber material can absorb more incident energy than the high-damping silicone as the damping layer. As for the damping layer shapes, the composite damping layer structure with a honeycomb shape achieves the best energy absorption among all structures. The comparison and analysis of the energy absorption effects when the damping layer thicknesses are 10, 20, and 25 mm reveal that a 20 mm-thick damping layer shows the best energy absorption effect. The current findings can provide theoretical foundation and data support for the application of composite damping layers to the seismic design of underground engineering structures.

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