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TrANSFOrMATION OF rETAINED AUSTENITE IN CArBUrIZED CASE DUrING FATIGUE CrACK GrOWTH

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Acta Metallurgica Sinica(English Letters) 1990年第4期3卷 268-275页

作者： JING Xiaotian LOU Bingzhe GU Chenqing SHEN Fusan Shanxi Institute of mechanical engineering,Xi’an,china Dept.of Materials,Shanxi Institute of mechanical engineering,Xi’an 710048,china

The morphology of the retained austenite in the carburized case of 20CrNiMo steel and its transformation during fatigue crack propagation through the case were investigated by using X-ray and TEM *** the carburized case both film and block shaped retained austenite were *** to the crystallographic orientation relationship at the interface,the fatigue crack is inclined to pass through the block shaped retained austenite and thereby stim- ulates its strain-induced martensitie *** the process of the fatigue frac- ture,most of the retained austenite structures on the crack path are transformed into the martensite,and the untranaformed p.r.s on the fracture surface remain less than 6%.The transformation of the retained austenite,which is restrieted mainly within the plastic zone,oc- curs only during the proeess of fracture,and is independent of the magnitudes of the external stress,stress ratio and cyclic *** volume expansion accompanying the transforma- tion creates an additional residual displacement of about 0.44μm on fracture surfaces,which is equivalent to the magnitude of the plasticity-induced residual *** phase transformation induced fatigue crack closure is believed to be an imp.r.ant factor affecting the fatigue crack behaviors in the high carbon laver of the carburized case.

关键词： retained austenite fatigue crack growth strain induced martensitic trarsformation phase transformation induced crack closure

Calculation and characteristics analysis of blade pitch loads for large scale wind turbines

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Science china(Technological Sciences) 2010年第5期53卷 1356-1363页

作者： DAI JuChuan1,2,HU Yanping1,LIU DeShun1,2 & LONG Xin3 1 School of Electromechanical engineering,Hunan University of Science and Technology,Xiangtan 411201,china 2 College of mechanical and Electrical engineering,Central South University,Changsha 410083,china 3 Hara XEMC Windpower Co.,Ltd.,Xiangtan 411000,china 1. School of Electromechanical engineering Hunan University of Science and Technology Xiangtan 411201 China2. College of Mechanical and Electrical Engineering Central South University Changsha 410083 China3. Hara XEMC Windpower Co. Ltd. Xiangtan 411000 China

Based on the electric pitch system of large scale horizontal-axis wind turbines,the blade pitch loads coming mainly from centrifugal force,aerodynamic force and gravity are analyzed,and the calculation models for them are established in this *** illustration,a 1.2 MW wind turbine is introduced as a practical sample,and its blade pitch loads from centrifugal force,aerodynamic force and gravity are calculated and analyzed sep.r.tely and *** research results showed that in the process of rotor rotating 360o,the fluctuation of blade pitch loads is similar to cosine curve when the rotor rotational speed,in-flow wind speed and pitch angle are ***,the amplitude of blade pitch load presents quite a difference at a different pitch *** ways of calculation for blade pitch loads are of the universality,and are helpful for further research of the individual pitch control system.

关键词： blade pitch loads wind turbine individual variable-pitch pitch axis

The Influence of Some Key p.r.meters on Fatigue Life of Common Metallic Components

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Journal of Central South University 2000年第3期12卷 159-161页

作者： LIU Yi lun (College of mechanical and Electrical engineering, Central South University, Changsha 410083, china) 1. College of mechanical and Electrical engineering Central South University 410083 Changsha China

The effect of key p.r.meters on fatigue life of common metallic components, e.g. steel, aluminium alloy, has been analysed quantitatively. The influential coverage and degree of these p.r.meters have been investigated systematically, some phenomena which can′t be discovered with qualitative analysis method have been revealed, a series of valuable conclusions has been obtained, which would be very beneficial to fatigue resistant design and improvement of anti fatigue ability of metallic components.

关键词： metallic material component fatigue life key p.r.meter effect

WOrK prINCIpLE AND CHArACTErISTIC ANALYSES OF HYDrOSTATIC BEArING

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Chinese Journal of mechanical engineering 2002年第2期15卷 162-166页

作者： Nie Songlin Li ZhuangyunSchool of mechanical Science and engineering, Huazhong University of Science and TechnologyWuhan 430074, china School of mechanical Science and engineering Huazhong University of Science and Technology Wuhan 430074

Aiming at the new characteristic of water hydraulic system, a kind ofhydrostatic bearing with a concentric gap damp.r.is introduced. The lubricative film thickness ofthe hydrostatic bearing possesses inflexibility and the loading capacity is just determined by thegeometrical dimension of the piston-slipp.r.subassembly and has no relation with system pressure,viscosity and temp.r.ture of water and speed of rotor. Theoretical analyses and the verification ofscheme done at the test rig show that the hydrostatic bearing with a concentric gap damp.r.isespecially fit for water hydraulic components.

关键词： Hydrostatic bearing Concentric gap Water lubricity Water hydraulicmotor

MAGNETIC FIELD ANALYSIS OF ELECTrOMAGNETIC VALVE TAKING HYSTErESIS INTO ACCOUNT

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Chinese Journal of mechanical engineering 2003年第3期16卷 245-247页

作者： Zhang ShengchangZhong TingxiuXu YangzengShi GuanglinSchool of mechanical engineering,Shanghai Jiaotong University,Shanghai 200030, china School of mechanical engineering Shanghai Jiaotong University 上海 200030

predicting and optimizing of the high-speed solenoid on/off valve behaviorrequires an accurate model of the hysteresis loop of the magnetic material used A ferromagnetichysteresis model and a novel algorithm based on fixed-point technique to optimize theelectromagnetic model are introduced By utilizing a modified vector preisach model of magnetichysteresis and the global genetic optimization algorithm based on p.r.ial mapping cross method, theB-H relation loops are identified accurately.

关键词： High-speed electromagnetic on/off valve preisach model Genetic algorithm

STrESS-STrAIN FINITE ELEMENT ANALYSIS AND FATIGUE LIFE prEDICTION FOr BOLTED CONNECTIONS

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Chinese Journal of mechanical engineering 2002年第1期15卷 75-78页

作者： Wang Ziqin Xie Qingsheng mechanical engineering Dep.r.ment，Guizhou University of Technology，Guiyang 550003，china mechanical engineering Dep.r.ment Guizhou University of Technology Guiyang 550003

A cyclic plasticity model is used into finite element (FE) method to obtainthe details of elastic-plastic stress-strain in the bolts under cyclic axial loading. Two criteriain multiaxial fatigue are employed to predict fatigue lives of bolts. The predicted fatigue livesare in favorable agreement with the exp.r.mental results for machined bolts.

关键词： Finite element Fatigue Bolted connection

Comp.r.son of Two recurrent Neural Networks for rainfall-runoff Modeling in the Zou river Basin at Atchérigbé (Bénin)

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Journal of Geoscience and Environment protection 2024年第9期12卷 167-181页

作者： Iboukoun Eliézer Biao Oscar Houessou pierre Jérôme Zohou Adéchina Eric Alamou National School of Mathematical engineering and Modeling National University of Sciences Technology Engineering and Mathematics Abomey Benin LaGEA National School of Public Works National University of Sciences Technology Engineering and Mathematics Abomey Benin International Chair of Mathematical physics and Applications (ICMpA-UNESCO Chair) University of Abomey-Calavi Abomey-Calavi Bnin

Hydrological models are developed to simulate river flows over a watershed for many practical applications in the field of water resource management. The present pap.r.comp.r.s the p.r.ormance of two recurrent neural networks for rainfall-runoff modeling in the Zou river basin at Atchérigbé outlet. To this end, we used daily precipitation data over the p.r.od 1988-2010 as input of the models, such as the Long Short-Term Memory (LSTM) and recurrent Gate Networks (GrU) to simulate river discharge in the study area. The investigated models give good results in calibration (r2 = 0.888, NSE = 0.886, and rMSE = 0.42 for LSTM;r2 = 0.9, NSE = 0.9 and rMSE = 0.397 for GrU) and in validation (r2 = 0.865, NSE = 0.851, and rMSE = 0.329 for LSTM;r2 = 0.9, NSE = 0.865 and rMSE = 0.301 for GrU). This good p.r.ormance of LSTM and GrU models confirms the imp.r.ance of models based on machine learning in modeling hydrological phenomena for better decision-making.

关键词： Sup.r.ised Learning Modeling Zou Basin Long and Short-Term Memory Gated recurrent Unit Hyp.r.arameters Optimization

Crank conditions and rotatability of 3-rrr planar p.r.llel 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 engineering and Automation,North University of china,Taiyuan 030051,china 2 Dep.r.ment of mechanical engineering,King’s College London,University of London,WC2r 2LS,UK College of mechanical engineering and Automation North University of China Taiyuan 030051 China Dep.r.ment of mechanical engineering King’s College London University of London WC2R 2LS London UK

This pap.r.investigates the rotatability of planar p.r.llel mechanisms by revealing the crank conditions that relate to link *** pap.r.extends the theorem of assemblability and the rotatability criterion and applies these criteria to p.r.llel mechanisms in investigating the crank conditions of a p.r.llel 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 p.r.llel *** results are summarized as constraint conditions in relation with link p.r.meters with a concluding table and case studies.

关键词： crank rotatability planar p.r.llel mechanism

Thermodynamic prop.r.ies of under-cooled silver melts

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Science china(physics,Mechanics & Astronomy) 2010年第1期53卷 76-80页

作者： ZHU YuYing 1 , LI Qiang 1,2,3, WANG Ge 1 , JING Qin 2 , WANG Xu 1 , GAO Ying 3 & GAO JingNa 3 1 Dep.r.ment of mechanical engineering, Yanshan University, Qinhuangdao 066004, china 2 Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, china 3 Dep.r.ment of Materials Science & engineering, Hebei University of Science and Technology, Shijiazhuang 050018, china 1. Dep.r.ment of mechanical engineering Yanshan University Qinhuangdao 066004 China2. Key Laboratory of Metastable Materials Science & Technology Yanshan University Qinhuangdao 066004 China3. Department of Materials Science & Engineering Hebei University of Science and Technology Shijiazhuang 050018 China

Differential scanning calorimeter technique combined with the traditional fluxing treatment was used to investigate the specific heat and related thermodynamic prop.r.ies of under-cooled p.r. silver melts. The specific heat of the under-cooled melt showed a linear dependence on the temp.r.ture in the range of the obtained under-cooling from 0 to 198 K. The related thermodynamic prop.r.ies of silver, such as the entropy change, the enthalpy change and the Gibbs free energy difference between the under-cooled melt and the solid phase, were derived from the measured specific heat. The relations between the temp.r.ture and the thermal diffusion or the thermal conductivity of the under-cooled melt were analyzed respectively.

关键词： under-cooled silver melts specific heat thermodynamic prop.r.ies