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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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In-plane mechanical properties of a novel hybrid auxetic structure

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SMART MATERIALS AND STRUCTURES 2022年第7期31卷 075003-075003页

作者： Fan, Peng Chen, Yu Xiong, Jian Hu, Hong Hong Kong Polytech Univ Inst Text & Clothing Hong Kong Peoples R China Harbin Inst Technol Ctr Composite Mat & Struct Harbin Peoples R China Xi An Jiao Tong Univ Dept Engn Mech State Key Lab Strength & Vibrat Mech Struct Soft Machines Lab Xian Peoples R China Jinan Univ Coll Packaging Engn Packaging Engn Inst Zhuhai Peoples R China Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

This paper presents a novel hybrid auxetic structure with enhanced mechanical properties, combining the re-entrant and double-arrowhead structures, based on the structural stretching-dominated deformation mechanism. The unit cell of the developed hybrid structure comprises an external quadrilateral frame and an internal arrowhead part. The theoretical analysis model for predicting its in-plane mechanical properties in the two principal directions is presented and verified by both numerical simulations and experimental measurements. On this basis, a parametric study on the in-plane mechanical properties of the hybrid structure is performed to optimize geometrical parameters. The results show that both the negative Poisson's ratio behavior and the elastic properties of the hybrid structure can be enhanced by increasing the length of the vertical wall or reducing the angle of the inclined wall in the internal arrowhead part. The hybrid structure, with the obvious difference in elastic properties between the two principle directions, can be obtained by individually adjusting the width of the hybrid unit cell, while the elastic properties in bothdirections can be improved by simultaneously reducing the length of the vertical wall and the width of the hybrid unit cell. In addition, compared with the re-entrant and double-arrowhead structures, the hybrid structure demonstrates higher elastic moduli and a wider range of Poisson's ratios from negative to positive. The study provides guidance for the optimized design of hybrid auxetic structures in practical applications.

关键词： auxetic structure negative Poisson's ratio mechanical properties

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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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Large potential of strengthening the land carbon sink in China through anthropogenic interventions

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Science Bulletin 2024年第16期69卷 2622-2631页

作者： Xu Yue Hao Zhou Yang Cao Hong Liao Xiaofei Lu Zhen Yu Wenping Yuan Zhu Liu Yadong Lei Stephen Sitch Jürgen Knauer Huijun Wang Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&Technology(NUIST)Nanjing 210044China College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China Jiangsu Nanjing Environmental Monitoring Center Nanjing 210013China Key Laboratory of Agrometeorology of Jiangsu Province Institute of EcologySchool of Applied MeteorologyNUISTNanjing 210044China Institute of Carbon Neutrality Sino-French Institute for Earth System ScienceCollege of Urban and Environmental SciencesPeking UniversityBeijing 100871China Department of Earth System Science Tsinghua UniversityBeijing 100084China State Key Laboratory of Severe Weather and Key Laboratory of Atmospheric Chemistry of CMA Chinese Academy of Meteorological SciencesBeijing 100081China College of Life and Environmental Sciences University of ExeterExeter EX44RJUK Hawkesbury Institute for the Environment Western Sydney UniversityPenrith 2751Australia Key Laboratory of Meteorological Disaster Ministry of EducationJoint International Research Laboratory of Climate and Environment ChangeCollaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNUISTNanjing 210044China

The terrestrial ecosystem in China mitigates 21%-45%of the national contemporary fossil fuel CO_(2) emissions every *** and strengthening the land carbon sink is essential for reaching China’s target of carbon ***,this sink is subject to large uncertainties due to the joint impacts of climate change,air pollution,and human ***,we explore the potential of strengthening land carbon sink in China through anthropogenic interventions,including forestation,ozone reduction,and litter removal,taking advantage of a well-validated dynamic vegetation model and meteorological forcings from 16 climate *** anthropogenic interventions,considering Shared Socioeconomic Pathways(SSP)scenarios,the land sink is projected to be 0.26-0.56 Pg C a^(-1) at 2060,to which climate change contributes 0.06-0.13 Pg C a^(-1) and CO_(2) fertilization contributes 0.08-0.44 Pg C a^(-1) with the stronger effects for higher emission *** anthropogenic interventions,under a close-to-neutral emission scenario(SSP1-2.6),the land sink becomes 0.47-0.57 Pg C a^(-1) at 2060,including the contributions of 0.12 Pg C a^(-1) by conservative forestation,0.07 Pg C a^(-1) by ozone pollution control,and 0.06-0.16 Pg C a^(-1) by 20%litter removal over planted *** sink can mitigate 90%-110% of the residue anthropogenic carbon emissions in 2060,providing a solid foundation for the carbon neutrality in China.

关键词： Carbon sink Forestation Ozone Litter removal

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Structural damage detection via combining weighted strategy with trace Lasso

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ADVANCES IN STRUCTURAL engineering 2019年第3期22卷 597-612页

作者： Chen, Chengbin Pan, Chudong Chen, Zepeng Yu, Ling Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Guangdong Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Guangdong Peoples R China

With the rapid development of computation technologies, swarm intelligence-based algorithms become an innovative technique used for addressing structural damage detection issues, but traditional swarm intelligence-based structural damage detection methods often face with insufficient detection accuracy and lower robustness to noise. As an exploring attempt, a novel structural damage detection method is proposed to tackle the above deficiency via combining weighted strategy with trace least absolute shrinkage and selection operator (Lasso). First, an objective function is defined for the structural damage detection optimization problem by using structural modal parameters;a weighted strategy and the trace Lasso are also involved into the objection function. A novel antlion optimizer algorithm is then employed as a solution solver to the structural damage detection optimization problem. To assess the capability of the proposed structural damage detection method, two numerical simulations and a series of laboratory experiments are performed, and a comparative study on effects of different parameters, such as weighted coefficients, regularization parameters and damage patterns, on the proposed structural damage detection methods are also carried out. Illustrated results show that the proposed structural damage detection method via combining weighted strategy with trace Lasso is able to accurately locate structural damages and quantify damage severities of structures.

关键词： antlion optimizer algorithm sparse regularization structural damage detection trace Lasso weighted strategy

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Seismic behavior of large-scale FRP–recycled aggregate concrete–steel columns with shear connectors

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Earthquake engineering and engineering Vibration 2019年第4期18卷 823-844页

作者： Zeng Lan Li Lijuan Yang Xianqian Liu Feng School of Civil and Transportation Engineering Guangdong University of Technology Guangzhou 510006 China MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou 510632 China Architectural Design and Research Institute of Guangdong Province Guangzhou 510000 China

The application of fi ber-reinforced polymer (FRP) composites for the development of high-performance composite structural systems has received signifi cant recent research attention. A composite of FRP–recycled aggregate concrete (RAC)–steel column (FRSC), consisting of an outer FRP tube, an inner steel tube and annular RAC fi lled between two tubes, is proposed herein to facilitate green disposal of demolished concrete and to improve the ductility of concrete columns for earthquake resistance. To better understand the seismic behavior of FRSCs, quasi-static tests of large-scale basalt FRSCs with shear connectors were conducted. The infl uence of the recycled coarse aggregate (RCA) replacement percentage, shear connectors and axial loading method on the lateral load and deformation capacity, energy dissipation and cumulative damage were analyzed to evaluate the seismic behavior of FRSCs. The test results show that FRSCs have good seismic behavior, which was evidenced by high lateral loads, excellent ductility and energy dissipation capacity, indicating RAC is applicable in FRSCs. Shear connectors can signifi cantly postpone the steel buckling and increase the lateral loads of FRSCs, but weaken the deformation capacity and energy dissipation performance.

关键词： recycled aggregate concrete (RAC) fi ber-reinforced polymer (FRP) FRP–RAC–steel column (FRSC) shear connector seismic behavior

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On the periodic solutions of the three-body problem

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National Science Review 2019年第6期6卷 1070-1071页

作者： Shijun Liao Xiaoming Li Advanced Center of Computing School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University School of Physics and Astronomy Shanghai Jiao Tong University MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University

The motion of three bodies that attract each other by universal gravitation was first investigated by Newton [1] and was reconsidered by many great mathematicians and scientists, including Euler, Lagrange, Poincaré [2] and Hilbert. The famous three-body problem has had a great influence on physics, mathematics and non-linear dynamics. It has led to a new

关键词： On the periodic solutions of the three-body problem

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A computing method for bending problem of thin plate on Pasternak foundation

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ADVANCES IN MECHANICAL engineering 2020年第7期12卷

作者： Gan, Jiarong Yuan, Hong Li, Shanqing Peng, Qifeng Zhang, Huanliang Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Sch Mech & Construct Engn Guangzhou 510632 Peoples R China

The governing equation of the bending problem of simply supported thin plate on Pasternak foundation is degraded into two coupled lower order differential equations using the intermediate variable, which are a Helmholtz equation and a Laplace equation. A new solution of two-dimensional Helmholtz operator is proposed as shown in Appendix 1. The R-function and basic solutions of two-dimensional Helmholtz operator and Laplace operator are used to construct the corresponding quasi-Green function. The quasi-Green's functions satisfy the homogeneous boundary conditions of the problem. The Helmholtz equation and Laplace equation are transformed into integral equations applying corresponding Green's formula, the fundamental solution of the operator, and the boundary condition. A new boundary normalization equation is constructed to ensure the continuity of the integral kernels. The integral equations are discretized into the nonhomogeneous linear algebraic equations to proceed with numerical computing. Some numerical examples are given to verify the validity of the proposed method in calculating the problem with simple boundary conditions and polygonal boundary conditions. The required results are obtained through MATlab programming. The convergence of the method is discussed. The comparison with the analytic solution shows a good agreement, and it demonstrates the feasibility and efficiency of the method in this article.

关键词： Plate bending problem Pasternak foundation Helmholtz equation Laplace equation R-function Green's function

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Experimental study on mechanical properties and effective stress coefficient of water-saturated sandstone under hydraulic-mechanical coupling

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Arabian Journal of Geosciences 2022年第10期15卷 1-10页

作者： Ren, Sheng Zhao, Yanlin Lin, Hang Wang, Yixian Work Safety Key Lab on Prevention and Control of Gas and Roof Disaster for Southern Coal Mines Hunan University of Science and Technology Xiangtan China School of Resources Environment and Safety Engineering Hunan University of Science and Technology Xiangtan China School of Resource Safety Engineering Central South University Changsha China School of Civil Engineering Hefei University of Technology Hefei China

In order to study the hydraulic-mechanical coupling law of deep fractured rock aquifer, based on the existing principal of effective stress, this paper obtained the mechanical parameters such as axial stress, confining pressure, and pore water pressure through the conventional triaxial compression test, hydraulic-mechanical coupling test under triaxial compression condition, and numerical fitting of water-saturated sandstone, so as to obtain the effective stress coefficient and related mechanical conclusions. The results showed that the axial stress had a positive linear relationship with the confining pressure. Peak strength and deformation modulus of water-saturated sandstone were positively correlated with confining pressure and negatively correlated with pore water pressure, while Poisson’s ratio was opposite. Under the same confining pressure, the effective stress coefficient of water-saturated sandstone was positively correlated with Poisson’s ratio and negatively correlated with deformation modulus. The effective stress coefficient obtained by numerical fitting was a bilinear function of pore water pressure and volumetric stress, and the effective stress coefficient was positively correlated with pore water pressure and negatively correlated with volumetric stress.

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