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Lattice Dynamics Models to Predict Transmission Properties of Flexural Waves in One-Dimensional Atom Chains with Defects

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Acta Mechanica Solida Sinica 2023年第1期36卷 105-115页

作者： Hao Wu Shihua Huang Jianyi Luo Laitong He Youdi Kuang School of Mechanics and Construction Engineering MOE Key Laboratory of Disaster Forecast and Control in EngineeringJinan UniversityGuangzhou 510632China School of Electro-Mechanical Engineering Zhongkai University of Agriculture and EngineeringZhuhai 519041China School of Applied Physics and Materials Wuyi UniversityJiangmen 529000China School of Civil Engineering and Architecture Wuyi UniversityJiangmen 529000China

Flexural waves usually propagate in one-and two-dimensional *** further our understanding on their transmission properties from the viewpoint of discrete lattice dynamics,we systematically established analytical atom chain models with mass defects and side *** mechanisms of the Bragg scattering and the local resonance corresponding to mass defects and side branches,respectively,are elucidated by means of the present *** results from the models show that increasing the number of mass defects or side branches decreases the transmission magnitude gradually,and the finite-width phononic bandgap may form due to the periodical arrangement of *** interplay between the local resonance and the Bragg scattering gives rise to the narrow phononic bandgap for lattice chains only with periodical side *** width of the bandgap strongly depends on the stiffness of side *** transmission is insensitive to the tensile strain considered for both kinds of defects,but significantly decreases with an increase in damping or wave *** present work helps further our understanding on the dynamics of flexural waves.

关键词： Transmission of flexural waves Lattice dynamics of chains Defects Damping Tensile strains

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Theoretical and Experimental Study on Tension–Torsion Coupling Vibration for Time-Varying Elevator Traction System

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Acta Mechanica Solida Sinica 2023年第6期36卷 899-913页

作者： Peng Xu Qifeng Peng Fusong Jin Jianghong Xue Hong Yuan MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction EngineeringJinan UniversityGuangzhou 51063China University of Health and Rehabilitation Sciences Qingdao 266071China School of Architectural Engineering Guangzhou Institute of Science and TechnologyGuangzhou 510540China Qingdao Xinghua Intelligent Equipment Co. Ltd.Qingdao 266114China

Elevators used in ultra-high buildings are prone to vibrating due to their ultra-long traction ropes,which significantly affects the comfort and safety of high-speed ***,vibration of the elevator has always been a topic of research *** paper presents a theoretical model for analyzing the tension–torsion coupling vibration of the time-varying elevator traction *** constitutive relations with the tension–torsion coupling effect of the wire rope are reduced by analyzing the deformation mechanism of the spiral winding wire *** on Hamilton’s principle,the equations of motion and corresponding boundary conditions for the tension–torsion coupling vibration of the elevator traction system are *** Galerkin method is employed to account for the influence of nonlinear boundary conditions and to transform the equations of motion into discrete ones with variable coefficients of time,which are solved using the Newmark-β*** accuracy of the proposed model is justified by the good agreement between theoretical predictions and experimental results,following which,the influence of the operation status and structural parameters of the elevator traction system on its vibration performance is discussed in detail.

关键词： Elevator traction system Wire rope Tension–torsion vibration Time-varying

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A Unified Approach Toward Simulating Constant and Varying Amplitude Fatigue Failure Effects of Metals with Fast and Efficient Algorithms

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Acta Mechanica Solida Sinica 2021年第1期34卷 53-64页

作者： Si-Yu Wang Lin Zhan Hui-Feng Xi Heng Xiao College of Mechanics and Construction Engineering and MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou510632China

A new finite strain elastoplastic J2-flow model is established with an explicit formulation of work-hardening and softening effects up to eventual failure,in which both a new flow rule free of yielding and an asymptotically vanishing stress limit are *** novelties of this new model are as follows:(i)Fatigue failure effects under repeated loading conditions with either constant or varying amplitudes are automatically characterized as inherent response features;(ii)neither additional damage-like variables nor failure criteria need to be involved;and(iii)both high-and low-cycle fatigue effects may be simultaneously treated.A fast and efficient algorithm of high accuracy is proposed for directly simulating high-and medium-high-cycle fatigue failure effects under repeated loading *** this goal,a direct and explicit relationship between the fatigue life and the stress amplitude is obtained by means of explicit and direct procedures of integrating the coupled elastoplastic rate equations for any given number of loading-unloading cycles with varying stress *** examples suggest that the new algorithm is much more fast and efficient than usual tedious and very time-consuming integration procedures.

关键词： Metals Finite strain Elastoplasticity Fatigue failure Direct algorithm

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Tomographic inversion of OBS converted shear waves:case study of profile EW6 in the Dongsha area

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Acta Oceanologica Sinica 2024年第8期43卷 13-25页

作者： Genggeng Wen Kuiyuan Wan Shaohong Xia Xiuwei Ye Huilong Xu Chaoyan Fan Jinghe Cao Shunshan Xu CEA Key Laboratory of Earthquake Monitoring and Disaster Mitigation Technology Guangdong Earthquake AgencyGuangzhou 510070China Guangdong Science and Technology Collaborative Innovation Center for Earthquake Prevention and Disaster Mitigation Guangzhou 510070China MOE Key Laboratory of Disaster Forecast and Control in Engineering-Urban Earthquake Safety Laboratory Guangzhou 510070China CAS Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China 6 Centro de Geociencias Universidad Nacional Autónoma de MéxicoQuerétaroC.P.76230Mexico

Studies of converted S-wave data recorded on the ocean bottom seismometer(OBS)allow for the estimation of crustal S-wave velocity,from which is further derived the Vp/Vs ratio to constrain the crustal lithology and geophysical *** a precise S-wave velocity model is important for deep structural research,and inversion of converted S-waves provides a potential ***,the inversion of the converted S-wave remains a weakness because of the complexity of the seismic ray path and the inconsistent conversion *** this study,we introduced two travel time correction methods for the S-wave velocity inversion and imaged different S-wave velocity structures in accordance with the corresponding corrected S-wave phases using seismic data of profile EW6 in the northeastern South China Sea(SCS).The two inversion models show a similar trend in velocities,and the velocity difference is<0.15 km/s(mostly in the range of 0–0.1 km/s),indicating the accuracy of the two travel time correction methods and the reliability of the inversion *** to simulations of seismic ray tracing based on different models,the velocity of sediments is the primary influencing factor in ray tracing for S-wave *** the sedimentary layer has high velocities,the near offset crustal S-wave refractions cannot be *** contrast,the ray tracing of Moho S-wave reflections was not significantly impacted by the velocity of the *** two travel time correction methods have their own advantages,and the application of different approaches is based on additional *** works provide an important reference for future improvements in converted S-wave research.

关键词： converted S-wave S-wave velocity structure inversion ocean bottom seismometer northeastern South China Sea

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High Resolution Mode Shapes Identification of Bridge Using Limited Sensors 6th

High Resolution Mode Shapes Identification of Bridge Using L...

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6th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures, SMAR 2022

作者： Nie, Zhenhua Xia, Guanghao Ma, Hongwei College of Science and Engineering Jinan University Guangdong Guangzhou China The Key Laboratory of Disaster Forecast and Control in Engineering Guangzhou Guangdong China Dongguan University of Technology Dongguan China

ISBN: (纸本)9789819933617

In this paper, a new method is proposed for high resolution mode shapes identification of bridge using a limited number of sensors based on proper orthogonal decomposition (POD). Through the physical interpretation of the POD for a simple bridge under moving load, the components of generalize coordinate of POD are verified as the instantaneous status of the modals of the bridge. Based on the physical interpretation, the results proved that each component of the POD consists of a mode shape and the dynamic information of this mode, so that the mode shape can be identified by filtering the dynamic information. This mode shape with a high resolution is completely different from the traditional method which can only provide a spare mode shape because of the limitation of sensors. The simulation results proved that the proposed method can accurately identify the mode shapes with a high resolution. © Tongji University Press 2024.

关键词： Information filtering

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Photo-Activated Snap-Through of Nematic Shallow Spherical Shells

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Acta Mechanica Solida Sinica 2022年第2期35卷 239-247页

作者： Yanli Lin Linghui He Renhuai Liu MOE Key Lab of Disaster and Control in Engineering Institute of Applied MechanicsJinan UniversityGuangzhou 510632China CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of ChinaHefei 230026China

Photo-responsive nematic polymers can transduce light into mechanical work,but the rate is limited by the quasi-static *** enhance the work output,a strat・egy of exploiting photo-triggered snap-through of glassy nematic shallow spherical shells with hemeotropic director alignment is examined *** criterion for the nonlinear instability is derived analytically by using the modified iteration *** is shown that,for thin shells of small height and large basal radius,snap-through can be caused by an incident light with moderate irradiation *** phenomenon may inspire some new designs of contactless and ultra-fast actuation devices with high-rate output of mechanical work.

关键词： Nematic shell Snap-through Ultra-fast actuation

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A new approach for non-Gaussian vibration analysis of hyperbolic tangent package with a critical component

A new approach for non-Gaussian vibration analysis of hyperb...

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作者： Yang, Song-Ping Su, Ri-Qing Wang, Zhi-Wei Chen, Yu Packaging Engineering Institute College of Packaging Engineering Jinan University Zhuhai China MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou China Key Laboratory of Product Packaging and Logistics of Guangdong Higher Education Institutes Jinan University Zhuhai China International Energy College/Energy and Electricity Research Center Jinan University Zhuhai China

A new approach is proposed to analyze the non-Gaussian random vibration of hyperbolic tangent package. Firstly, the non-Gaussian vibration noise of specified mean, variance, skewness, and kurtosis is developed by Hermite polynomial and verified by Gaussian mixture model theory. Secondly, next to analyzing an analytical and numerical response of the two degrees of freedom linear package, the acceleration response of the two degrees of freedom hyperbolic tangent package system under non-Gaussian vibration excitation is obtained though the Hermite polynomial and Runge–Kutta method, and the effects of the external excitation and system parameters are investigated. Finally, on the basis of the first-passage probability of the acceleration response, the reliability analysis method is introduced. The analysis provides a guidance to the vibration reliability analysis and packaging optimization design. © 2022 John Wiley & Sons Ltd.

关键词： Reliability analysis

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Research on the Application of Small Caliber Pilot Jacking Method Under Silt Geology 1

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9th International Conference on Civil engineering, ICCE 2022

作者： Wu, Qixing Huang, Jieming Li, Qijun Liu, Haoran School of Mechanics and Construction Engineering Jinan University Guangdong Guangzhou510632 China MOE Key Laboratory of Disaster Forecast and Control in Engineering Jinan University Guangdong Guangzhou510632 China Foshan Sanxin Municipal Engineering Co. Ltd. Guangdong Foshan528000 China

ISBN: (数字)9789819925322

ISBN: (纸本)9789819925315

With the rapid development of urban scale in China, the number of drainage pipes and new construction has also increased rapidly, and pipeline maintenance and new not suitable for excavation construction and silt formation construction due to limited space, and introduce the working principle, construction design, construct construction are facing problems such as environmental protection and narrow construction sites. The use of small-diameter pilot top pulling method can effectively overcome the difficulties of drainage pipeline projects in bustling urban areas that areion process and process of the construction method. Combined with the construction example of a small-caliber pilot top pull method of a drainage pipeline project in Zhongshan City, it shows that the construction technology has the advantages of high precision, space saving, small environmental impact and can be constructed on narrow roads, which can provide reference for similar projects and has greater promotion and application significance. © 2023, The Author(s).

关键词： Drainage

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Unified simulation of hardening and softening effects for metals up to failure

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Applied Mathematics and Mechanics(English Edition) 2021年第12期42卷 1685-1702页

作者： Siyu WANG Lin ZHAN Huifeng XI O.T.BRUHNS Heng XIAO School of Mechanics and Construction Engineering MOE Key Lab of Disaster Forecast and Control in EngineeringJinan UniversityGuangzhou 510632China Institute of Mechanics Ruhr-University BochumBochum D-44780Germany

Toward accurately simulating both hardening and softening effects for metals up to failure,a new finite strain elastoplastic J2-flow model is proposed with the yield strength therein as a function of the plastic work in the explicit *** no need to identify any adjustable parameters,the uniaxial stress-strain response predicted from this new model is shown to automatically and accurately match any given data from monotonic uniaxial extension tests of *** such,the objectives in three respects are achieved for the first time,i.e.,(i)both the hardening and softening effects up to failure can be simulated in the sense of matching test data with no errors,(ii)the usual tedious implicit procedures toward identifying numerous unknown parameters need not be involved and can be totally bypassed,and(iii)the model applicability can be ensured in a broad sense for various metallic materials with markedly different transition effects from hardening to *** the new model,the complete response features of stretched bars and twisted tubes up to failure are studied,including the failure effects of bars under monotonic extension and tubes under monotonic torsion and,furthermore,the fatigue failure effects of bars under cyclic *** results show accurate agreement with the uniaxial data,and the results for both the shear stress and the normal stress at the finite torsion display realistic hardening-to-softening transition effects for the first time.

关键词： metal hardening softening failure necking yield strength accurate approach

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Advanced modeling of the absorption enhancement of black carbon particles in chamber experiments by considering the morphology and coating thickness

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Frontiers of Environmental Science & engineering 2024年第9期18卷 129-142页

作者： Xiaodong Wei Jianlin Hu Chao Liu Xiaodong Xie Junjie Yin Song Guo Min Hu Jianfei Peng Huijun Wang Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Key Laboratory of Meteorological Disaster(Ministry of Education)Nanjing University of Information Science and TechnologyNanjing 210044China Nansen−Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China East China Air Traffic Management Bureau CAAC Shanghai 200335China State Key Joint Laboratory of Environmental Simulation and Pollution Control International Joint Laboratory for Regional Pollution Control(IJRC)(Ministry of Education)College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Tianjin Key Laboratory of Urban Transport Emission Research&State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control College of Environmental Science and EngineeringNankai UniversityTianjin 300071China

Measurements studies have shown that the absorption of radiation by black carbon(BC)increases as the particles ***,there are significant discrepancies between the measured and modeled absorption enhancement(E_(abs)),largely due to the simplifications used in modeling the mixing states and shape *** took advantage of chamber experiments on BC aging and developed an efficient method to resolve the particle shape based on the relationship between the coating fraction(ΔD_(ve)/D_(ve),0)and fractal dimension(D_(f)),which can also reflect the variations of D_(f)during the whole BC aging *** with externally and partly mixed states(0≤ΔD_(ve)/D_(ve),0≤0.5)can be considered to be uniformly distributed with the D_(f)values of 1.8–2.1,whereas the Df values are constrained in the range 2.2–2.8 for fully mixed states(ΔD_(ve)/D_(ve),0>0.5).The morphological parameters(i.e.,the effective density and the dynamic shape factor)were compared with the measured values to verify the simulated *** simulated mean deviations of morphological parameters were smaller than 8%for the method resolving the particle *** applying a realistic shape and refractive index,the mass absorption cross for fully mixed states can be improved by 11%compared with a simplified core–shell *** on our understanding of the influence of D_(f)andΔD_(ve)/D_(ve),0 on E_(abs),we propose a two-stage calibration equation to correct the E_(abs)values estimated by the core–shell model,which reduces the simulation error in the Mie calculation by 6%–14%.

关键词： Black carbon Mixing states Fractal dimension Dynamic shape factor Absorption enhancement

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