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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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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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Finite Element Analysis of Subsurface Damage of Optical Glass after Grinding

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Journal of Physics: Conference Series 2021年第2期1802卷

作者： Wei Su Wenhao Luo Xianshan Dong Renhuai Liu MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou 510632 China Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou 510610 China School of Mechanics and Construction Engineering Jinan University Guangzhou 510632 China

The interaction between abrasive particles and optical element surface can result in various forms of subsurface damage while removing the material. In order to obtain the stress distribution during optical glass grinding, the finite element analysis of optical glass grinding is carried out by using ANSYS software. The stress distribution of optical glass was obtained by establishing the grinding model of consolidated abrasive and free abrasive. The simulation results show that different abrasives have different damage degrees to the glass surface, which provides a useful reference for improving the quality of optical material processing technology.

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Residual Stress Analysis of Laser Welding Between Output Needle and Helix

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Journal of Physics: Conference Series 2021年第2期1802卷

In order to obtain the welding stress of the output needle and helix, a finite element model is established and the mesh at the weld is refined to evaluate the welding residual stress. ANSYS parameter design language is used to simulate the motion load of welding heat source. Based on the exact calculation of the temperature field, the corresponding thermal units are converted into structural units to calculate the welding residual stress. Finally, the thermal stress distribution curve and residual stress distribution trend are obtained after post-treatment.

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Computer Transient Simulation for Dual In-Line Package through Finite Element Analysis and ANASYS Software

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Journal of Physics: Conference Series 2021年第1期2033卷

作者： Wei Su Wenhao Luo Xianshan Dong Si Chen Agam Tomar 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 Guangzhou China School of Mechanics and Construction Engineering Jinan University Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia

The reliability of the DIP package is studied by numerical simulation. Firstly, the DIP package, fixture and metal steel are modeled. Based on this, variable thickness papers are laid on the sample. According to the experiment, corresponding excitation and boundary condition are set. Then, the transient analysis result of DIP package is obtained through numerical simulation. The results show the relation of different thickness papers and acceleration-time curve, which provides a beneficial reference for the optimization of DIP packing.

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Wave Soldering Coupled Thermal-mechanical Simulation of Multi-layer Ceramic Capacitors

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IOP Conference Series: Earth and Environmental Science 2021年第4期632卷

作者： Wei Su Wenhao Luo Junkui Li Renhuai Liu MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou 510632 China. Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou 510610 China. School of Mechanics and Construction Engineering Jinan University Guangzhou 510632 China

In this paper, the thermal-mechanical coupling finite element analysis of MLCC wave soldering with heat conduction and heat convection is calculated, and the steady-state temperature field and transient temperature field as well as the stress distribution of MLCC are obtained. Using the finite element analysis method of indirect thermal-mechanical coupling, the stress analysis is carried out with the temperature field as the boundary condition, and the thermal-structural coupling model is established. By analyzing the thermal stress of MLCC, the weak parts sensitive to thermal stress are determined, which provides a useful reference for solving the reliability problem of MLCC wave soldering.

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Harmonic Response Analysis for Ball Grid Array Package Using Computer Finite Element Simulation

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Journal of Physics: Conference Series 2021年第1期2033卷

BGA package is selected as the research object in this paper. Workbench (finite elemental analysis tool in ANSYS) is used for harmonic response analysis. The author lays several paper sheets on the sample and builds the finite element model of clamp, ceramic and metal plate. Then, the model analysis is carried out. Based on this, it is converted to harmonic response analysis. According to the results, the author has found that there is no relation between the number of paper sheets and acceleration-frequency result. It promotes the development of electronic packaging reliability.

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Numerical Simulation of Random Vibration Analysis for Ball Grid Array Package

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IOP Conference Series: Earth and Environmental Science 2021年第3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 Guangzhou China School of Mechanics and Construction Engineering Jinan University Guangzhou China Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia Perth Australia

This paper uses ANSYS Workbench (a finite element analysis software) to simulate BGA ceramic packing. The author models fixture, ceramic and metal steel. Then different thickness papers are laid on the BGA product. By random vibration analysis, the natural frequency and mode of the sample are obtained. According the results, the author discusses the relationship between different thickness papers and PSD-frequency curve. It provides a benefit instruction for the design of BGA packing.

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A unified and explicit approach for accurately characterizing the hardening-softening behavior of metals with a tension-compression strength asymmetry

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IOP Conference Series: Materials Science and engineering 2020年第1期770卷

作者： H F Xi L Zhan S Y Wang Z H Xu H Xiao School of Mechanics & Construction Engineering and MOE Lab for Disaster Forecast & Control in Engineering Jinan University 510632 Guangzhou China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University 710049 Xi'an China

A unified and explicit approach is proposed for accurately characterizing a complex hardening-softening behavior of metals with a tension-compression strength asymmetry. The proposed approach provides an explicit determining of the yield strength as plastic work function and contains the following three procedures: (i) a mode invariant is introduced to express the yield strength as a sum of two uncoupled parts for the tension and the compression case; (ii) a new expression for the plastic work is derived explicitly in terms of the uniaxial stress-strain function and, then, the yield strength function can be determined jointly from the just-mentioned two functions with the axial strain as parametric variable; and, finally, (iii) the axial stress-strain function is presented for representing the hardening-softening features. With these procedures, test data over the entire hardening-softening range can be fitted independently for the tension and the compression cases by directly treating the uniaxial stress-strain function. As such, tedious trial-and-error procedures are bypassed in identifying numerous unknown parameters. Numerical examples show that accurate simulations may be achieved with the proposed approach.

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An explicit simulation of arbitrarily-shaped pseudo-elastic hysteresis loops in shape-memory alloys

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IOP Conference Series: Materials Science and engineering 2020年第1期770卷

作者： S Y Wang L Zhan Z H Xu H F Xi H Xiao School of Mechanics & Construction Engineering and MOE Lab for Disaster Forecast & Control in Engineering Jinan University 510632 Guangzhou China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University 710049 Xi'an China

A new and explicit approach is proposed for accurately simulating pseudo-elastic hysteresis loops of any shape in shape-memory alloys (SMAs). For this purpose, new finite strain elastoplastic J2-flow equations are established for modeling finite strain behavior of SMAs. A stress-strain loop of any given shape in each uniaxial loading-unloading cycle is derived exactly from these equations. Then, a new technique is further introduced toward integrating usual piecewise linear splines into a single smooth interpolating function in a unified form. With the proposed equations and technique, test data for SMA hysteresis loops of any shape may be automatically fitted with high accuracy based on a single-parameter identification.

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