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Experimental study on the energy absorption characteristics of viscoelastic damping layers

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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Satellites of the Broucke-Hadjidemetriou-Hénon family of periodic unequal-mass three-body orbits

arXiv

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arXiv 2020年

作者： Li, Xiaoming Liao, Shijun MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China Department of Earth Atmospheric and Planetary Sciences Massachusetts Institute of Technology CambridgeMA02139 United States School of Physics and Astronomy Shanghai Jiaotong University Shanghai200240 China Center of Advanced Computing School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai200240 China

The Broucke-Hadjidemetriou-Hénon’s (BHH) orbits are a family of periodic orbits of the three-body system with the simplest topological free group word a, while the BHH satellites have free group words ak (k > 1), where k is the topological exponent. Janković and Dmitrašinović [Phy. Rev. Lett. 116, 064301 (2016)] reported 57 new BHH satellites with equal mass and found that at a fixed energy the relationship between the angular momentum (L) and the topologically rescaled period (T/k) is the same for both of the BHH orbits (k = 1) and the BHH satellites (k > 1). In this letter, we report 419,743 new BHH orbits (k = 1) and 179,253 new BHH satellites (k > 1) of the three-body system with unequal mass, which have never been reported, to the best of our knowledge. Among these newly-found 598,996 BBH orbits and satellites, about 33.5% (i.e., 200,686) are linearly stable and thus many among them might be observed in practice. Besides, we discover that, for the three-body system with unequal mass at a fixed energy, relationship between the angular momentum (L) and topologically rescaled period (T/k) of the BHH satellites (k > 1) is different from that of the BHH orbits (k = 1). Copyright © 2020, The Authors. All rights reserved.

关键词： Satellites

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Periodic satellite orbits of the Broucke-Hadjidemetriou-Hénon family of three-body system with unequal masses

Research Square

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Research Square 2020年

作者： Li, Xiaoming Liao, Shijun Department of Earth Atmospheric and Planetary Sciences Massachusetts Institute of Technology CambridgeMA02139 United States MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China School of Physics and Astronomy Shanghai Jiaotong University Shanghai200240 China Center of Advanced Computing School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai200240 China

Triple systems are common and key objects in astronomy. The three-body problem has received much more attention in recent years1–3. All observed periodic triple stars systems4–6 belong to the Broucke-Hadjidemetriou-Hénon’s (BHH) family7–9. The BHH orbits are a family of periodic orbits of the three-body system with the simplest topological free group word10 a, while Janković and Dmitrašinović 1 gained 58 equal-mass BHH satellite orbits which have free group words ak (k > 1), where k is the topological exponent. However, the BHH satellite orbits with equal mass is lack of realistic meaning because they do not exist in practice. Here we present 419743 new BHH orbits and 179253 new BHH satellites (k > 1) for three-body system with unequal mass. Especially, 48761 among the 179253 new BHH satellites are stable and have unequal masses. It suggests that these 48761 stable BHH satellites could be found by the observation. Besides, for the three-body system with equal mass at a fixed energy, it was demonstrated that the relationship between the angular momentum (L) and topological scaled period (T/k) of the BHH satellites is the same as that of the BHH orbits1. However, we found that this does not hold for the three-body system with unequal mass. Our findings have broad impact for the astrophysical scenario: they could inspire the theoretical and observational study of the triple system, the formation of triple stars11, the gravitational waves pattern12 and the gravitational waves observation13 of the triple system. © 2020, CC BY.

关键词： Satellites

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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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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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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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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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Visualization Analysis of Markov Chain Based on CiteSpace

Visualization Analysis of Markov Chain Based on CiteSpace

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作者： Songping Yang Ranni Zhang Yongyi Chen Fan Yang He Wang Ru Zhang Packaging Engineering Institute Jinan University MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University School of Marxism Jinan University School of Intelligent Science and Engineering Jinan University Electrical Engineering Institute Jinan University School of Electrical Engineering Jinan University International Business School Jinan University

Since markov chain is widely used in various fields, the relevant literatures of markov chain theories are analyzed base on CiteSpace in this paper, adopting 10,000 literatures in CNKI and 10,000 literatures in WOS as datas. The relationship among markov chain, monte carlo integral and bayesian theory is analyzed primarily. What's more, the hidden markov model, markov random field, markov decision process and grey-markov model derived from markov chain are investigated emphatically. Ultimately, we reviews the development history of markov chain, makes a visual analysis of the authors, sorts out the research status of markov chain, and makes a comprehensive review of the application of markov chain.

关键词： Visualization Monte Carlo Citespace

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