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Design,Development and Testing of the JTech Bolt for Use in static,quasi-static and Dynamic Domains

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Journal of Civil Engineering and Architecture 2024年第6期18卷 282-295页

作者： Trent Roberts Jennmar Australia Pty Ltd. 40-44 Anzac Avenue Smeaton Grange NSW 2567Australia

Designing a rock reinforcement element requires knowledge of:geomechanical behaviour,interaction of the reinforcement element with rock mass and the element’s mechanistic response in static and dynamic *** this knowledge the JTech bolt was developed and subjected to a thorough program to test,gather data and validate the bolt performance in varying *** conducting FE(finite element)modeling,the simulation reviews the JTech bolt design evaluating the effects of threadbar geometric variation,threadbar and nut engagement results under high stress,coating friction response and effects of thread tolerance extremes on the failure *** results determine safety factors,tolerances and quality management *** manufactured,in-situ system testing,laboratory and underground short encapsulation testing,resin mixing testing,double shear testing and dynamic testing at varying velocity and mass,determine the system’s capacity and effectiveness in static,quasi-static and dynamic mining *** this paper,the process and results are described.

关键词： Rock reinforcement geomechanical behavior static quasi-static dynamic domains

quasi-static Analysis of Thrust-loaded Angular Contact Ball Bearings Part Ⅱ:Results and Discussion

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Chinese Journal of Mechanical Engineering 2012年第1期25卷 81-87页

作者： CHEN Wenhua1,2,MA Zikui1,GAO Liang1,LI Xinglin3,and PAN Jun2 1 Institute of Mechanical Design,Zhejiang University,Hangzhou 310027,China 2 Institute of Mechanical Design and Manufacturing,Zhejiang Sci-Tech University,Hangzhou 310018,China 3 State Testing Laboratory of Hangzhou Bearing Test & Research Center,Hangzhou 310022,China Institute of Mechanical Design Zhejiang University Hangzhou China Institute of Mechanical Design and Manufacturing Zhejiang Sci-Tech University Hangzhou China State Testing Laboratory of Hangzhou Bearing Test & Research Center Hangzhou China

Ball bearings are widely employed mechanical components characterized by high precision and quality,and usually play important roles in various rotary machines and *** advanced applications require a deep understanding of their various kinematic and tribological characteristics that are essential to predict the fatigue endurance,relieve the vibration and minimize the power dissipation of ball bearings in particular *** angular contact ball bearing under a specified operating condition is simulated with the quasi-static/creepage analytical model proposed in the preceding *** results demonstrate that the ball bearing is a statically determinate *** the balls spin on both inner and outer races means the ball is controlled by neither the inner nor the outer *** friction between the ball and raceway renders the inner and outer contact angles *** larger the coefficient of friction is,the larger the angle *** tangential traction perpendicular to the rolling direction due to the spin induces a gyro-like rotation of the ball with respect to the raceway even if no inertial effects are *** tangential elastic compliance of contacting surfaces gives rise to locked areas within the contact patch and transforms the sliding lines from circles into *** differential slip due to the close conformity of the ball and raceway makes the sliding and traction distributions asymmetric,which will influence the location of the spinning center of the ball with respect to the *** quasi-static/creepage model can be used to reveal the operating behaviors of ball bearings running under steady conditions and to optimize the design of ball bearings for specific applications.

关键词： ball bearing quasi-static creepage differential slip tangential elastic compliance

Formability of AA 2219-O sheet under quasi-static,electromagnetic dynamic,and mechanical dynamic tensile loadings

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Journal of Materials Science & Technology 2021年第11期70卷 125-135页

作者： Hongliang Su Liang Huang Jianjun Li Wang Xiao Hui Zhu Fei Feng Hongwei Li Siliang Yan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China

The mechanism by which electromagnetic forming(EMF)enhances the formability of metals is unclear owing to the coupling effect of multi-physics *** the present work,the associated formability improvement mechanisms were qualitatively categorized and *** was realized by comparing the formability of fully annealed 2219 aluminum alloy(AA 2219-O)sheet under quasi-static(QS),electromagnetic dynamic(EM),and mechanical dynamic(MD)tensile *** was found that the forming limit of AA 2219-O sheet under EM tensile loading was significantly(45.4%)higher than that under QS tensile loading,and was marginally(3.7%–4.3%)higher than that under MD tensile *** addition,the forming limit of AA 2219-O sheet demonstrated a negative dependency on the strain rate within the range of the dynamic tensile tests *** deformation conditions common to EM and MD tensile loadings were responsible for the significant formability improvement compared with QS tensile *** particular,the inertial effect was *** different deformation conditions that distinguish EM tensile loading from MD tensile loading resulted in the marginal improvement in *** was caused by the absence of a sustaining contact force at the later deformation stage and the lower strain *** body force exerted little influence on the formability improvement,and the thermal effect under the two dynamic tensile loadings was negligible.

关键词： Formability Aluminum alloy sheet quasi-static Electromagnetic dynamic Mechanical dynamic Tensile loading

Theoretical research and experimental validation of quasi-static load spectra on bogie frame structures of high-speed trains

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Acta Mechanica Sinica 2014年第6期30卷 901-909页

作者： Ning Zhu Shou-Guang Sun Qiang Li Hua Zou Engineering Research Center of Structure Reliability and Operation Measurement Technology of Rail Guided Vehicles Ministry of EducationBeijing Jiaotong University

One of the major problems in structural fatigue life analysis is establishing structural load spectra under actual operating *** study conducts theoretical research and experimental validation of quasi-static load spectra on bogie frame structures of high-speed *** quasistatic load series that corresponds to quasi-static deformation modes are identified according to the structural form and bearing conditions of high-speed train bogie ***,a force-measuring frame is designed and manufactured based on the quasi-static load *** load decoupling model of the quasi-static load series is then established via calibration ***-static load–time histories,together with online tests and decoupling analysis,are obtained for the intermediate range of the Beijing—Shanghai dedicated passenger *** damage consistency calibration of the quasi-static discrete load spectra is performed according to a damage consistency criterion and a genetic *** calibrated damage that corresponds with the quasi-static discrete load spectra satisfies the safety requirements of bogie frames.

关键词： Load spectra quasi-static Bogie frame Calibration High-speed train

Temperature Effect on the Mechanical Behavior of Acrylic Polymers under quasi-static and Dynamic Loading

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上海交通大学学报 2004年第Z2期38卷 89-95页

作者： Tao Suo Yulong Li Hong Yu Fei Xu Zhongbin Tang Lei Li School of Aeronautics Northwestern Polytechnical University Xi''an710072 China School of Aeronautics Northwestern Polytechnical University Xi''an710072 China School of Aeronautics Northwestern Polytechnical University Xi''an710072 China School of Aeronautics Northwestern Polytechnical University Xi''an710072 China School of Aeronautics Northwestern Polytechnical University Xi''an710072 China Beijing Institute of Aeronautical Materials Beijing100095China

In this paper, the mechanical behavior of acrylic polymers at elevated temperature was investigated. Four acrylic polymers were tested at high strain rate by using compression Hopkinson bar and at quasi-static strain rate by using an Instron servo hydraulic axial testing machine with the testing temperature from 218K to 393K. The results show that the mechanical property of acrylic polymers depends heavily on the testing temperature. The yield stress and Young's modulus were found to decrease with increasing temperature at low strain rate. At very low temperature, the materials display typical brittle fracture; however their plasticity improves remarkably at high temperatures. The predictions of the mechanical behavior including the effect of temperature and strain rate using a proposed theoretical model have a good agreement with experimental results.

关键词： acrylic polymer compression Hopkinson bar quasi-static dynamic fracture

quasi-static and Dynanmic Deformation Behaviors of Medium-Carbon Steels in a Wide Temperature Range

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Materials Sciences and Applications 2011年第6期2卷 572-577页

作者： Byoungchul Hwang 不详

This paper presents a study of the quasistatic and dynamic deformation behaviors of conventional and microalloyed medium-carbon steels in a wide temperature range. As strain rate increased, the flow stress increased at room temperature, but occasionally did not at elevated temperatures. The flow stress of the microalloyed steel containing precipitates was less sensitive to strain rate at room temperature than that of the conventional steel due to a relatively larger activation length. Microstructural observation of the steels deformed after compression test indicated that inhomogeneous deformation became more serious with increasing strain rate and temperature without fracturing in the highly localized region.

关键词： quasi-static Dynamic Deformation Behavior Medium-Carbon Steel Precipitate

Microstructure and quasi-static Mechanical Behavior of Cryoforged AA2519 Alloy

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Materials Sciences and Applications 2019年第2期10卷 137-149页

作者： Amin Azimi Gbadebo Moses Owolabi Hamid Fallahdoost Nikhil Kumar Horace Whitworth Department of Mechanical Engineering Howard University Washington DC USA Department of Mechanical Engineering Materials Science and Engineering Program Binghamton University (SUNY) Binghamton NY USA

In this study, AA2519 alloy was initially processed by multi axial forging (MAF) at room and cryogenic temperatures. Subsequently, the microstructure and the mechanical behavior of the processed samples under quasi-static loading were investigated to determine the influence of cryogenic forging on alloys’ subgrains dimensions, grain boundaries interactions, strength, ductility and toughness. In addition, the failure mechanisms at the tensile rupture surfaces were characterized using scanning electron micro-scope (SEM). The results show significant improvements in the strength, ductility and toughness of the alloy as a result of the cryogenic MAF process. The formation of nanoscale crystallite microstructure, heavily deformed grains with high density of grain boundaries and second phase breakage to finer particles were characterized as the main reasons for the increase in the mechanical properties of the cryogenic forged samples. The cryogenic processing of the alloy resulted in the formation of an ultrafine grained material with tensile strength and toughness that are ~41% and ~80% higher respectively after 2 cycles MAF when compared with the materials processed at ambient temperature. The fractography analysis on the tested materials shows a substantial ductility improvement in the cryoforged (CF) samples when compared to the room temperature forged (RTF) samples which is in alignment with their stress-strain profiles. However, extended forging at higher cycles than 2 cycles led only to increase in strength at the expense of ductility for both the CF and RTF samples.

关键词： AA2519 Aluminum Alloy Cryogenic Forging quasi-static Mechanical Behavior Microstructure Investigation Fractography Analysis

FEM and EFG quasi-static Explicit Buckling Analysis for Thin-Walled Members

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Open Journal of Civil Engineering 2017年第3期7卷 432-452页

作者： Lihua Huang Bin Li Yuefang Wang Faculty of Infrastructure Engineering Dalian University of Technology Dalian China

The quasi-static explicit finite element method (FEM) and element free Galerkin (EFG) method are applied to trace the post-buckling equilibrium path of thin-walled members in this paper. The factors that primarily control the explicit buckling solutions, such as the computation time, loading function and dynamic relaxation, are investigated and suggested for the buckling analysis of thin-walled members. Three examples of different buckling modes, namely snap-through, overall and local buckling, are studied based on the implicit FEM, quasi-static explicit FEM and EFG method via the commercial software LS-DYNA. The convergence rate and accuracy of the explicit methods are compared with the conventional implicit arc-length method. It is drawn that EFG quasi-static explicit buckling analysis presents the same accurate results as implicit finite element solution, but is without convergence problem and of less-consumption of computing time than FEM.

关键词： quasi-static Explicit Solution Buckling Analysis Thin-Walled Members FEM EFG

A Comparative Experimental Investigation of 3D Angle-interlock Woven Composite between quasi-static Tension and Three-point Bending Loading Conditions

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A Comparative Experimental Investigation of 3D Angle-interlo...