检索结果-南通市图书馆

Design and application of friction pair surface modification coating for remanufacturing

在线全文

学校读者我要写书评

暂无评论

Friction 2017年第3期5卷 351-360页

作者： Haidou WANG Guozheng MA Binshi XU Qingsong YONG Pengfei HE National Key lab.for Remanufacturing Academy of Armored Forces Engineering Beijing 100072 China National Key lab.for Remanufacturing Academy of Armored Forces Engineering Beijing 100072 ChinaChina Aerodynamics Research and Development Center Mianyang 621000 China

Friction,wear,and contact fatigue are the main causes of energy loss,material waste,and equipment *** aim of remanufacturing is to repair and modify the damaged equipment surface,and the surface coating is the major material that allows the remanufactured parts to be used in a new round of ***,the design and preparation of surface coatings are very important to repair,strengthen,or modify the friction pairs,in order to ensure long-term operation of the remanufactured ***1y,a lot of research on designing and preparing friction pair surface modification coatings has been conducted by the National Key lab.ratory for Remanufacturing (NKLR).The research conducted achieved the following goals:the mechanism of micro/nano multilayer surface modification coatings with long-term efficacy life was revealed,and the corresponding design considerations and preparation methods of nanocrystalline micro tribological coatings were innovatively developed.A series of new 'two-step' processes to prepare sulfide solid lubricating coatings were *** competitive failure mechanism of the surface coating in simultaneous wear and fatigue conditions was revealed,and some composite coatings with dual properties of wear resistance and fatigue resistance were *** on the stress distribution of friction surface contact areas and the piezoelectric effect,a failure warning intelligent coating is designed and *** coatings have been successfully applied to critical friction components,such as the spindle of large centrifugal compressors,engine cylinder piston components,and driver gear pairs.

关键词： remanufacturing surface coating solid lubrication contact fatigue intelligent sensing coating

Fabrication of laminated TiB2-B4C/Cu-Ni composites by electroplating and spark plasma sintering

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2017年第10期33卷 1172-1176页

作者： Ziyi Wu Jinyong Zhang Taojie Shi Fan Zhang Liwen Lei Han Xiao Zhengyi Fu State Key lab.of Advanced Technology for Material Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

We proposed a new method, electroplating followed by spark plasma sintering（SPS）, to fabricate laminated TiB2-B4 C/Cu-Ni composites with high strength and high toughness. It is found that a thin intermediate Cu layer can effectively enhance the strength of the interface between the ceramics and the metals, resulting in a high flexural strength and toughness of the laminated TiB2-B4 C composites simultaneously. A flexural strength and fracture toughness of 651 MPa and 11.6 MPam^（1/2） respectively,are achieved, an approximately 90% improvement over TiB2-B4 C bulk.

关键词： Laminated structure Electroplating Spark plasma sintering B4C ceramic

Synthesis of Nano-Size AlN Powders by Carbothermal Reduction from Plasma-Assisted Ball Milling Precursor

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2016年第7期18卷 759-763页

作者：刘志杰王文春杨德正王森戴乐阳 Key lab.of Materials Modification (Dalian University of Technology) Ministry of Education Marine Engineering Institute Jimei University

Nano-size aluminum nitride （A1N） powders have been successfully synthesized with a high efficiency method through annealing from milling assisted by discharge plasma （p-milling） alumina （Al2O3） precursors. The characterization of the p-milling Al2O3 powders and the synthesized AlN are investigated. Compared to conventional ball milling （c-milling）, it can be found that the precursors by p-milling have a finer grain size with a higher specific surface area, which lead to a faster reaction efficiency and higher conversion to A1N at lower temperatures. The activation energy of p-milling Al2O3 is found to be 371.5 kJ/mol, a value that is much less than the reported value of the unmilled and the conventional milled Al2O3. Meanwhile, the synthesized AlN powders have unique features, such as an irregular lamp-like morphology with uniform particle distribution and fine average particle size. The results are attributed to the unique synergistic effect of p-milling, which is the effect of deformation, fracture, and cold welding of Al2O3 powders resulting from ball milling, that will be enhanced due to the introduction of discharge plasma.

关键词： aluminum nitride, ball milling, thermal temperature plasma, alumina

Study on Corrosion Behavior of Pearlitic Rail Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Minerals and Materials Characterization and Engineering 2011年第7期10卷 573-581页

作者： S. Samal A. Bhattaacharyya S.K. Mitra Department of Metallurgical and Material Engineering National Institute of TechnologyDurgapur 713 209 India Information Materials lab. School of Materials Science and Engineering Inha University253 Yonghyun-Dong Nam-Gu Incheon 402-751 Korea

The present study is an attempt to find out the effect of environmental corrosion on the commonly used pearlitic rail steel. The cases of corrosion of rail under Indian environment have been studied. It has been found that in marine environment both the yield strength and tensile strength decreases with increasing corrosion rate. In acidic environment yield strength increased with increasing corrosion rate, although the tensile strength decreases with increasing corrosion rate.

关键词： atmospheric corrosion marine environment quasi-cleavage fracture peralitic steel.

PROBABILISTIC MODELS FOR LONG fatigue CRACK GROWTH RATES OF LZ50 AXLE STEEL

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2005年第8期26卷 1093-1099页

作者： ZHAO Yong-xiang（赵永翔） HE Chao-ming（何朝明） YANG Bing（杨冰） HUANG Yu-zhong（黄郁仲） GAO Qing（高庆） WU Ping-bo（邬平波） SW Jiaotong Univ State Key Lab Tract Power Chengdu 610031 Peoples R China

Experimental study is performed on the probabilistic models for the long fatigue crack growth rates （da/dN） of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN-△K relations, the confidence-based da/dN-△K relations, and the probabilistic- and confidence-based da/dN-△K relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are availab.e and feasible.

关键词： LZ50 steel long fatigue crack growth rate average stress threshold probabilistic model

Microstructure Characteristics of SiC Particle-Reinforced Aluminum Matrix Composites Coatings by Cold Spraying

在线全文

学校读者我要写书评

暂无评论

稀有金属材料与工程 2012年第S1期41卷 460-463页

作者： Wang Hongtao Ji Gangchang Chen Xiao Bai Xiaobo Chen Qinyu Jiujiang Univ Jiujiang Key Lab Green Remfg Jiujiang 332005 Peoples R China

A dense Al/SiCp composite coating with high volume fraction(60%)of nano SiCp reinforcement was fabricated by cold spraying of ball-milled Al-60SiCp composite *** morphologies evolution of the Al-60SiCp composite powder during ball milling and the microstructure and microhardness of the cold-sprayed Al-60SiCp composite coating were *** results show that Al particles undergone fracture deformation and nano SiC particles are uniformly distributed in soft Al matrix after ball milling.A dense Al-60SiCp composite coating can be fabricated by cold spraying of ball milled composite *** SiC particles in the cold-sprayed Al-60SiCp composites coating exhibit a reasonably uniform *** Hv0.5 microhardness of the Al-60SiCp composite coating is reached up to(5.30±0.53)GPa due to the enhancement of SiC particles,compared to(0.34±0.03)GPa for the pure Al bulk.

关键词： cold spraying ball milling aluminum matrix composites microstructure

Prediction of fatigue crack propagation lives based on machine learning and data-driven approach

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean Engineering and Science 2024年第6期9卷 592-604页

作者： Li Sun Xiaoping Huang State Key lab.of Ocean Engineering Shanghai JiaoTong UniversityShanghai 200240China

Numerous influence factors will lead to the inaccurate prediction of fatigue crack propagation(FCP)life of the metal structure based on the existing FCP model,while the prediction method based on machine learning(ML)and data-driven approach can provide a new idea for accurately predicting the FCP life of the metal *** response to the inconvenience of the online prediction method and the inaccu-racy of the offline prediction method,an improved offline prediction method based on data feedback is presented in this *** tests of reduced scale models of balcony opening corners in a cruise ship are conducted to obtain experimental data with respect to the a-N *** crack length corresponding to the cycle is trained using a support vector regression(SVR)and back propagation neural network(BP NN)*** prediction lives of test specimens are performed according to the online,offline,and improved offline prediction *** of the number of feedback data,the sequence length(SL)in the input set,and the cycle interval on prediction accuracy are *** generalization ability of the proposed method is validated by comparing the prediction results with the experimental data in the *** larger the number of feedback data,the higher the prediction *** results show that 1/5 and 1/2 feedback data are needed in the SVR and BP NN algorithm with SL is 5,***,the SVR algorithm and SL=5 are recommended for FCP life prediction using the improved offline prediction method.

关键词： Machine learning Data-driven FCP test Reduced scale model FCP life prediction

Scale dependence of tensile strength of micromachined polysilicon MEMS structures due to microstructural and dimensional constraints

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第16期46卷 1392-1397页

作者： Ding, JN Meng, YG Wen, SH Tsing Hua Univ Natl Tribol Lab Beijing 100084 Peoples R China

The success of microelectromechanical systems (MEMS) as a key technology in the 21st century depends in no small part on the solution of materials issues associated with the design and fabrication of complex MEMS devices. The reliable mechanical properties of these thin films are critical to the safety and functioning of these microdevices and should be accurately determined. In order to accomplish a reliable mechanical design of MEMS, a new microtensile test device using a magnetic-solenoid force actuator was developed to evaluate the mechanical properties of microfabricated polysilicon thin films with dimensions of 100—660 mm length, 20—200 mm width, and 2.4 mm thickness. It was found that the measured average value of Young抯 modulus, 164±1.2 GPa, falls within the theoretical bounds. The average fracture strength is 1.36 GPa with a standarddeviation of 0.14 GPa, and the Weibull modulus is 10.4—11.7, respectively. Statistical analysis of the specimen size effect on the tensile strength predicated the size effect on the length, the surface area and the volume of the specimens due tomicrostructural and dimensional constraints. The fracturestrength increases with the increase of the ratio of surfacearea to volume. In such cases the size effect can be tracedback to the ratio of surface area to volume as the governing parameter. The test data account for the uncertainties inmechanical properties and may be used in the future reliability design of polysilicon MEMS. The testing of 40specimens to failure results in a recommendation for design that the nominal strain be maintained below 0.0057.

关键词： microelectromechanical systems polysilicon elasticmodulus tensile strength size effect.

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

在线全文

学校读者我要写书评

暂无评论

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