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Solution of a hollow thick-wall cylinder subject to quadric function pressures and its limit when l→∞

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Science China(Technological Sciences) 2004年第2期47卷 229-236页

作者： LIU Zhubai1,SHAN Rui2.LIU Wen2.& NI Liyong1 1.college of mechanical {2.,Yanshan University,Qinhuangdao 066004,China 2.college of Science,Yanshan University,Qinhuangdao 066004,China 1. college of mechanical {2. Yanshan University 066004 Qinhuangdao China 2. college of Science Yanshan University 066004 Qinhuangdao China

The problem of a hollow thick-wall cylinder subject to quadric function pressures is solved with a new stress function, thus laying the basis for solving the spatial symmetric deformation of a hollow cylinder subject ... 详细信息

关键词： quadric function pressure, analytic solution, stress function, hollow cylinder.

Effect of Tocopherol on Antioxygenic Properties of Green Lubricating Oil

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Journal of Wuhan University of Technology(Materials Science) 2008年第3期23卷 289-292页

作者：肖志信 college of mechanical and {2. engineering Central South University Department of mechanical engineering Hunan Institute of TechnologyHengyang 421002China

Based on the needs of green motor oil, and in order to improve the antioxidation properties of green lubricating oil, the effect of tocopherol antioxidation properties of rapeseed oil was studied. Experiments of high temperature oxidation, antiwear and infra-red spectrum analysis were accomplished, the results show that the rapeseed oil including tocopherol can still keeps steady structure after high temperature oxidation, with a small variety of acid number, whose antioxygenic properties are improved evidently. Meanwhile, both thiocarbamate and vitamin C play an assistant role in tocopherol, which can make rapeseed oil to have better oxidation stability and keep excellent antiwear properties after high temperature oxidation.

关键词： rapeseed oil tocopherol antioxygenic properties

Crank conditions and rotatability of 3-RRR planar parallel mechanisms

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Science China(Technological Sciences) 2009年第12期52卷 3601-3612页

作者： LI RuiQin 1 &DAI Jian S 2.1.college of mechanical {2. and Automation,North University of China,Taiyuan 030051,China 2.Department of mechanical {2.,King’s college London,University of London,WC2. 2.S,UK college of mechanical {2. and Automation North University of China Taiyuan 030051 China Department of mechanical engineering King’s College London University of London WC2R 2LS London UK

This paper investigates the rotatability of planar parallel mechanisms by revealing the crank conditions that relate to link *** paper extends the theorem of assemblability and the rotatability criterion and applies these criteria to parallel mechanisms in investigating the crank conditions of a parallel mechanism,leading to classification of three types of crank existing conditions including three-crank’s,six-crank’s and nine-crank’s of 3-RRR planar parallel *** results are summarized as constraint conditions in relation with link parameters with a concluding table and case studies.

关键词： crank rotatability planar parallel mechanism

Diffusion and Oxidation Wear of PCBN Tool based on Thermodynamics

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Journal of Wuhan University of Technology(Materials Science) 2010年第2期25卷 265-271页

作者：邵芳 Binzhou Vacational college School of mechanical engineering Shandong University

The rules of diffusion wear and oxidation wear for PCBN cutting tools were analyzed based on thermodynamics theory. Dissolution concentrations in typical normal workpice materials of PCBN tool material at different temperature were then calculated. Diffusion reaction rules in high temperature were developed and analyzed using the Gibbs free energy criterion. The machining tests were conducted using the PCBN tools at different cutting speeds of 50, 95,100 and 180 m/min, feed of 0.1, 0.2.and depth of cut of 0.1, 0.8, 1, and 1.5 mm respectively on a PUMA300LM numerically-controlled lathe. It was found that the theoretical results were uniform with the experimental data, and the results will provide useful references for tool material design and selection.

关键词： thermodynamics PCBN tool diffusion wear oxidation wear

Energy-Based Prediction of Low Cycle Fatigue Life of High-Strength Structural Steel

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Journal of Iron and Steel Research International 2012年第10期19卷 47-53页

作者： LUO Yun-rong1,2. HUANG Chong-xiang1, GUO Yi2. WANG Qing-yuan1 (1. college of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan, China 2. college of {2. engineering, Sichuan University of Science and engineering, Zigong 643000, Sichuan, China) [a] college of Architecture and Environment. Sichuan University Chengdu 610065 Sichuan China [b] college of mechanical {2.. Sichuan University of Science and {2. Zigong 643000 Sichuan China

Energy-based models for predicting the low-cycle fatigue life of high-strength structural steels are presented. The models are based on energy dissipation during average of cycles, cycles to crack propagation and total cycles to failure. Plastic strain energy per cycle was determined and found as an important characteristic for initiation and propagation of fatigue cracks for high-strength structural steels. Fatigue strain-life curves were generated using plastic energy dissipation per cycle (loop area) and compared with the Coffin-Manson relation. Low cycle fatigue life was found similar from both methods. The material showed Masing-type behavior. The cyclic hysterisis energy per cycle was calculated from cyclic stress-strain parameters. The fracture surfaces of the fatigue samples were characterized by scanning electron microscope and the fracture mechanisms were discussed.

关键词： low cycle fatigue high-strength steel energy-based model fatigue life

Orientation angle rotatability of planar serial n-link manipulators

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Science China(Technological Sciences) 2010年第6期53卷 1620-1637页

作者： LI RuiQin1,XIAO DengHong1 & DAI Jian S2.1.college of mechanical {2. and Automation,North University of China,Taiyuan 030051,China 2.Department of mechanical {2.,King’s college London,University of London,London WC2. 2.S,UK 1. college of mechanical {2. and Automation North University of China Taiyuan 030051 China2. Department of Mechanical Engineering King’s College London University of London London WC2R 2LS UK

This paper presents a new method of analyzing the orientation angle rotatability of a planar serial n-link manipulator by examining the rotatability of its virtual equivalent *** orientation boundary region decomposition is proposed based on the polynomial discriminant derived from a serial three-link *** angle workspace indicates a set of angle ranges by which the end-effector can reach with certain orientation for every point in the reachable position *** introducing a virtual equivalent mechanism,the open-chain kinematic problem is converted into a close-chain mechanism,and the Grashof-type condition is used to examine the rotatability of the end-effector *** reachable position workspace can be divided into several Grashof intervals and non-Grashof intervals based on the extreme positions and singular configurations of a *** derived equations in this paper can be used to calculate the variation rule of the orientation angle workspace of any given planar serial n-link manipulator on the basis of its link *** orientation angle rotatability of a seven-link serial manipulator is solved by the proposed method and graphical representations of the orientation angle workspaces are mapped onto a three-dimensional coordinate *** theoretical approach has practical significance for the design of a highly dexterous serial n-link manipulator with proposed link relations.

关键词： Grashof criterion planar serial manipulator orientation angle workspace virtual equivalent mechanism

MOTION ANALYSIS AND DESIGN OF ACCUMULATOR FOR HYDRAULIC ROCK DRILL

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中国有色金属学会会刊：英文版 1996年第2期6卷 148-151页

作者： Liu Shixun(college of mechanical and {2. engineering, Central South University of Technology, Changsha 410083) CENT S UNIV TECHNOL COLL MECH & ELECT ENGNCHANGSHA 410083PEOPLES R CHINA

ＭＯＴＩＯＮＡＮＡＬＹＳＩＳＡＮＤＤＥＳＩＧＮＯＦＡＣＣＵＭＵＬＡＴＯＲＦＯＲＨＹＤＲＡＵＬＩＣＲＯＣＫＤＲＩＬＬＬｉｕＳｈｉｘｕｎ（ＣｏｌｌｅｇｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔｒｉｃａｌＥｎｇｉｎｅｅｒｉ... 详细信息

ＭＯＴＩＯＮＡＮＡＬＹＳＩＳＡＮＤＤＥＳＩＧＮＯＦＡＣＣＵＭＵＬＡＴＯＲＦＯＲＨＹＤＲＡＵＬＩＣＲＯＣＫＤＲＩＬＬＬｉｕＳｈｉｘｕｎ（ＣｏｌｌｅｇｅｏｆＭｅｃｈａｎｉｃａｌａｎｄＥｌｅｃｔｒｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＣｅｎｔｒａｌＳｏｕｔｈＵｎ...

关键词： hydraulic accumulator diaphragm service life stretching ratio parameter design,motion analvsis

Analysis on ignition and extinction of n-heptane in homogeneous systems

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Science China(Technological Sciences) 2005年第5期48卷 556-569页

作者： LIU Yongfeng1 & PEI Pucheng2.1. mechanical and electrical {2. Department, Beijing Institute of Civil {2. and Architec-ture, Beijing 100044, China 2. State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, China 1. mechanical and electrical {2. Department Beijing Institute of Civil Engineering and Architecture 100044 Beijing China 2. State Key Laboratory of Automotive Safety and Energy Tsinghua University 100084 Beijing China

To calculate ignition delay times, the governing equations about species and temperature, which are in a closed volume based on the theory of thermal explosion and in a continuously stirred flow reactor, are deducted. The method referred to steady state assumptions is based on the observation that due to very fast chemical processes in combustion problems many chemical species and reactions are in a quasi-steady state or partial equilibrium. When a species is assumed to be in the steady state, the corresponding differential equation can be replaced by an algebraic relation, which reduces the computational costs. The steady state solution of the reactor equations describes the three ignition temperature regimes and get “S-shaped curve”. The reduced simplified 4-step mechanism for n-heptane from 1011 elementary reactions leads with the steady state assumptions to linear differential equations, which is solved. The simulation results of the 4-step reduced mechanism for n-heptane are fitted well with the experiment data. At last, two important parameters are discussed thoroughly and the temperature perturbation is given. It reduces the computational efforts considerably without losing too much accuracy and further supplies numerical methods for turbulent combustion in the diesel engine.

关键词： ignition delay times, thermal runaway, steady state assumptions, continuously stirred flow reactor.

Tribological Properties of Dimpled Surface Alloying Layer on Carbon Steel

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Journal of Wuhan University of Technology(Materials Science) 2009年第2期24卷 218-222页

作者：万轶 Department of Materials Science & engineering Nanjing University of Science and Technology Department of mechanical and electrical {2. Yingtian College

The effect of surface structure and coating on tribological properties of 45^# carbon steel disc was analyzed. A Nd：YAG laser was used to generate rnicrodirnples on steel surfaces. Dimples with diameter of 150 rn and depth of 50 rn were distributed in an orbicular array on disc surface. Then the alloying element Mo was sputtered to 45# carbon steel disc surface by means of double glow plasma technology. Diffusion Mo alloying layer with 30min thickness and high hardness up to 0.02. was formed on the disc surface. Tribological experiments of three types samples （smooth, texturing and texturing＋alloying） were conducted with a pin-on-disc tribometer. It is found that the dimpled-samples are most effective for reducing friction in comparison with smooth steel surthces, improving the lubricating state from boundary to hydrodynamic region.

关键词： laser surface texturing double glow plasma surface alloying technology carbon steel tribological performance lubricating state