检索结果-南通市图书馆

Formation and evolution mechanism of metal whiskers in extreme aerospace environments:A review

在线全文

学校读者我要写书评

暂无评论

中国航空学报:英文版 2023年第9期36卷 1-13页

作者： Zekun WANG Shiming WANG School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444China Department of Mechanical Engineering Auburn UniversityAuburn AL 36849USA College of Engineering Science and Technology Shanghai Ocean UniversityShanghai 201306China Shanghai Engineering Research Center of Marine Renewable Energy Shanghai 201306China

The spontaneous growth and evolution mechanism of metal whiskers have long been scientific *** the development of the integration of electronic and electrical productions,short circuits and system failures are raised by metal whiskers *** the meantime,the related theories and mechanisms of whiskering problem are still vague,leading to a deficiency in the studies of environmental factors influencing the whisker ***,the extreme environments such as aerospace,have been proven the accelerators to the formation of metal whiskers,resulting in a severe threaten to equipment and devices working in such environments including satellite and military *** establish a comprehensive understanding to the whiskering process associated with their applicable control strategies,this study analyzes the growth phenomenon,influencing factors,formation process and evolution mechanism of metal whiskers in extreme service environments,puts forward the corresponding controlling strategies,offers a reference for the establishment of Chinese extreme aerospace strategic environment,and improves the reliability of aerospace systems.

关键词： aerospace Extreme environments Control strategy Metal whisker Reliability

Applications of magnesium alloys for aerospace:A review

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第10期11卷 3609-3619页

作者： Jingying Bai Yan Yang Chen Wen Jing Chen Gang Zhou Bin Jiang Xiaodong Peng Fusheng Pan School of Material Science and Engineering Chongqing UniversityChongqing 400044China Beijing Spacecrafts Manufacturing Co. LtdChina Academy of Space TechnologyBeijing 100094China

With the increasingly excellent performance of magnesium alloy materials, magnesium alloys are increasingly widely used under the urgent need for weight reduction in aerospace applications. However, due to the severe aviation environment, the strength, corrosion resistance and electrical conductivity of magnesium alloy materials need to be further improved. Many scholars are committed to studying higher comprehensive mechanical properties. Besides, they have studied surface treatment processes with space application characteristics, such as high emissivity oxidation and high anti-corrosion electroplating. To further improve the safety and reliability of magnesium alloys and expand their applications, this paper discusses several kinds of magnesium alloys and summarizes their research progress. The whole manuscript should be revised by an expert who has more experience on English writing. At the same time, the surface treatments of magnesium alloy materials for aerospace are analyzed. Besides, the application of magnesium alloy in aerospace field is summarized. With the in-depth research of many scholars, the improvement of material properties and the development of surface protection and functional technology, it is believed that magnesium alloys will be used in more and more aerospace applications and make more contributions to the aerospace field.

关键词： Magnesium alloy aerospace Application Review Surface treatment

A robust solution for hesitate phenomenon in pick up process of aerospace electromagnetic relay

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2013年第3期26卷 697-704页

作者： Ye Xuerong Deng Jie Ma Yue Zhai Guofu Yan Jihong School of Electrical Engineering and Automation Harbin Institute of Technology School of Mechanical and Electrical Engineering Harbin Institute of Technology

As for aerospace electromagnetic relay （AEMR） which is of small batches and having difficulty in automatic production, the uncertainty phenomenon is remarkable due to excessive manual work involved in the assembly and adjustment processes. This kind of uncertainty may increase the coil voltage difference （CVD） caused by hesitate phenomenon in the pick up process of AEMR. Taking a certain type of AEMR for example, the CVD problem in the actual producing process has been studied in this paper. The primary cause of this issue, two-steps of armature motion （namely hesitate phenomenon） in the pick up process, has been found by analyzing the matching characteristics of electromagnetic and mechanical torques of AEMR. Through the optimization of the matching characteristics, the two-steps of armature motion problem is solved by robust design of the return reed which is a key part of AEMR. The validity of this research has been proved by the comparison of characteristics of AMER before and after the optimization.

关键词： aerospace Coil voltage difference Electromagnetic relay Hesitate phenomenon Robust design

80 years education of aerospace science and technology in Tsinghua University

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2018年第9期31卷 1797-1804页

作者： Jie LU Yongli GAO Xiaojing WANG Chenyuan BAI Bing WANG Ziniu WU School of aerospace Engineering Tsinghua University

The development of aerospace science and technology largely relies on the education and academic contribution of students in universities covering aerospace science and technology. The School of aerospace Engineering of Tsinghua University, with a history of eighty years since the set-up of its Department of Aeronautical Engineering in 1938, graduated 5273 undergraduate students, 1939 master students and 931 Ph.D. students. This paper provides an overview and analysis of the data related to undergraduate, master and Ph.D. students of this school. These data include the historical evolution of number of students and the actual status of students like their various interests and academic performance. The data and information shared in this paper may be useful for comparative study and for those who need primitive data to study relevant issues such as mental health of students, promotion of gender balance and educational improvement.

关键词： Academic output aerospace Education Favorite activity Students

Quantified simulation research on harmonious factors in the leadership teams of aerospace enterprise group

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2007年第4期18卷 751-757页

作者： Yin Xingliang Hu Yunquan Yang Fuping hao Hanping Tang Ning Harbin Institute of Technology Harbin 150001 P. R. China China aerospace Science & Industry Corp. Beijing 100830 P. R. China Beijing Normal University Beijing 100875 P. R. China

A brief account of basic connotation and evaluation indexes system of harmonious leadership teams is given. On this basis, a simulation model is built by using the ARENA simulation software and the quantified simulation is carried out for the factors of harmonization of aerospace enterprise leadership teams. Moreover, by taking the characteristics of aerospace enterprise leadership teams into consideration, the comparison of harmonization quantified results of several typical leadership teams, especially on the comparative analysis of influencing degrees of moral characters and capabilities on the leadership teams overall harmonization is emphatically discussed. Finally, a conclusion is drawn.

关键词： harmonization aerospace leadership teams quantified simulation ARENA

Online condition diagnosis for a two-stage gearbox machinery of an aerospace utilization system using an ensemble multi-fault features indexing approach

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第5期32卷 1100-1110页

作者： Min ZHOU Ke WANG Yang WANG Kaiji LUO Hongyong FU Liang SI CAS Key Lab of Space Utilization Technology and Engineering Center for Space Utilization Chinese Academy of Sciences (CAS) University of Chinese Academy of Sciences

China manned space station is designed to operate for over ten years. Long-term and sustainable research on space science and technology will be conducted during its operation. The application payloads must meet the ‘‘long life and high reliability" mission requirement. Gearbox machinery is one of the essential devices in an aerospace utilization system, failure of which may lead to downtime loss even during some disastrous catastrophes. A fault diagnosis of gearbox has attracted attentions for its significance in preventing catastrophic accidents and guaranteeing sufficient maintenance. A novel fault diagnosis method based on the Ensemble Multi-Fault Features Indexing(EMFFI) approach is proposed for the condition monitoring of gearboxes. Different from traditional methods of signal analysis in the one-dimensional space, this study employs a supervised learning method to determine the faults of a gearbox in a two-dimensional space using the classification model established by training the features extracted automatically from diagnostic vibration signals captured. The proposed method mainly includes the following steps. First, the vibration signals are transformed into a bi-spectrum contour map utilizing bi-spectrum technology,which provides a basis for the following image-based feature extraction. Then, Speeded-Up Robustness Feature(SURF) is applied to automatically extract the image feature points of the bi-spectrum contour map using a multi-fault features indexing theory, and the feature dimension is reduced by Linear Discriminant Analysis(LDA). Finally, Random Forest(RF) is introduced to identify the fault types of the gearbox. The test results verify that the proposed method based on the multi-fault features indexing approach achieves the target of high diagnostic accuracy and can serve as a highly effective technique to discover faults in a gearbox machinery such as a two-stage one.

关键词： aerospace utilization system Condition diagnosis Fault feature index Gearbox machinery Health monitoring Vibration

Polymer composite for antistatic application in aerospace

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2020年第1期16卷 107-118页

作者： Ramdayal Yadav Manoj Tirumali Xungai Wang Minoo Naebe Balasubramanian Kandasubramanian Institute for Frontier Materials Deakin UniversityWaurn PondsVIC3216Australia Department of Metallurgical and Materials Engineering Defence Institute of Advanced Technology(DU)GirinagarPune411025India

The pheno menon of static electricity is unpredictable,particulariy when an aircraft flying at high altitude that causes the accumulation of static charges beyond a threshold value leading to the failure of its parts and systems including severe explosion and radio communication *** accumulation of static charges on aircraft is generated by the virtue of interaction between the outer surface of aircraft and the external environmental attributes encompasses air particles,ice,hail,dust,volcanic ash in addition to its triboelectric *** the recent years,advanced polymer-based composites or nanocomposites are preferred structural constituents for aircrafts due to their light weight and comparable mechanical properties,but such composite systems do not render low impedance path for charge flow and are subsequently vulnerable to effect of lightning strike and precipitation *** this context,it is essential to develop conductive composite systems from non-co nductive polymer natrix by nano fillerembodime *** advent of carbon-based nanocomposite/nano materials have adequately addressed such issues related to the nonco nductive polymer matrix and further turned into an avant-garde genre of *** current review envisioned to illustrate the detailed exploitation of various polymer nanocomposites in addition to especially mentioned epoxy composites based on carbon fillers like carbon black,carbon nanotube(single walled carbon nanotube and multi walled carbon nanotube) and graphene the development of antistatic application in aircra ft in addition to the static charge phenomenon and condition for its prevalence in avionic systems.

关键词： Static discharge system Nanocomposite Anti-static materials Electromagnetic interference aerospace applications

Influence of Shim Layers on Progressive Failure of a Composite Componentin Composite-Aluminum Bolted Joint in aerospace Structural Assembly

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2018年第1期35卷 188-202页

作者： Cephas Yaw Attahu An Luling Li Zhaoqing Gao Guoqiang Department of aerospace Manufacturing Engineering Jiangsu Key Laboratory of Precision and Micro-Manufacturing TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China AVIC Xi′an Aircraft Industry(Group)Company LTD Xi′an 710089P.R.China

The influence of varying shim layers on the progressive damage/failure of a composite component in a bolted composite-aluminum aerospace structural assembly was investigated using a non-linear three-dimensional(3 D)structural solid elements assembled model of a carbon fiber-reinforced polymer(CFRP)-aluminum single-lap joint with a titanium(Ti-6 Al-4 V)fastener and a washer generated with the commercial finite element(FE)software package,ABAQUS/Standard.A progressive failure algorithm written in Fortran code with a set of appropriate degradation rules was incorporated as a user subroutine in ABAQUS to simulate the non-linear damage behavior of the composite component in the composite-aluminum bolted aerospace *** assembled 3 DFE model simulated,as well as the specimen for the experimental testing consisted of a carbon-epoxy IMS-977-2 substrate,aluminum alloy 7075-T651 substrate,liquid shim(Hysol EA 9394),solid peelable fiberglass shim,a titanium fastener,and a *** distinction to previous investigations,the influence of shim layers(liquid shim and solid peelable fiberglass shim)inserted in-between the faying surfaces(CFRP and aluminum alloy substrates)were investigated by both numerical simulations and experimental *** simulated model and test specimens conformed to the standard test configurations for both civil and military *** numerical simulations correlated well with the experimental results and it has been found that:(1)The shimming procedure as agreed upon by the aerospace industry for the resolution of assembly gaps in bolted joints for composite materials is the same for a composite-aluminum structure;liquid shim series(0.3,0.5 and 0.7 mm thicknesses)prolonged the service life of the composite component whereas a solid peelable fiberglass shim most definitely had a better influence on the 0.9 assembly gap compared with the liquid shim;(2)The shim layers considerably influenced the structural strength of the composite component b

关键词： composite-aluminum progressive failure modeling finite element modeling single-lap bolted joint shimming aerospace structures

Comparative assessment of force,temperature,and wheel wear in sustainable grinding aerospace alloy using biolubricant

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2023年第1期18卷 1-33页

作者： Xin CUI Changhe LI Yanbin ZHANG Wenfeng DING Qinglong AN Bo LIU Hao Nan LI Zafar SAID Shubham SHARMA Runze LI Sujan DEBNATH School of Mechanical and Automotive Engineering Qingdao University of TechnologyQingdao 266520China State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHong KongChina College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China Sichuan Future aerospace Industry LLC. Shifang 618400China School of aerospace University of Nottingham Ningbo ChinaNingbo 315100China College of Engineering University of SharjahSharjah 27272United Arab Emirates Department of Mechanical Engineering IK Gujral Punjab Technical UniversityPunjab 144603India Department of Biomedical Engineering University of Southern CaliforniaLos AngelesCA 90089USA Mechanical Engineering Department Curtin UniversityMiri 98009Malaysia

The substitution of biolubricant for mineral cutting fluids in aerospace material grinding is an inevitable development direction,under the requirements of the worldwide carbon emission ***,serious tool wear and workpiece damage in difficult-to-machine material grinding challenges the availability of using biolubricants via minimum quantity *** primary cause for this condition is the unknown and complex influencing mechanisms of the biolubricant physicochemical properties on *** this review,a comparative assessment of grindability is performed using titanium alloy,nickel-based alloy,and high-strength ***,this work considers the physicochemical properties as the main factors,and the antifriction and heat dissipation behaviours of biolubricant in a high temperature and pressure interface are comprehensively ***,the comparative assessment of force,temperature,wheel wear and workpiece surface for titanium alloy,nickel-based alloy,and high-strength steel confirms that biolubricant is a potential replacement of traditional cutting fluids because of its improved lubrication and cooling ***-viscosity biolubricant and nano-enhancers with high thermal conductivity are recommended for titanium alloy to solve the burn puzzle of the *** with high viscosity and high fatty acid saturation characteristics should be used to overcome the bottleneck of wheel wear and nickel-based alloy surface *** nano-enhancers with high hardness and spherical characteristics are better ***,a different option is available for high-strength steel grinding,which needs low-viscosity biolubricant to address the debris breaking difficulty and wheel ***,the current challenges and potential methods are proposed to promote the application of biolubricant.

关键词： grinding aerospace difficult-to-machine material biolubricant physicochemical property grindability