机械设计中英文外文翻译文献.docx

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1、机械设计中英文外文翻译文献 (文档含英文原文和中文翻译) 中英文资料外文翻译 Fundamentals Of Machinery Design This introductory chapter is a general survey of machinery designFirst it presents the definition and major role of machinery design，the relationship between machinery and its componentsThen it gives an overview of machinery des

2、ign as a fundamental course and outlines a general procedure of machinery design followed by all the engineersFinally, it lists the contents of the course and the primary goals to be achieved 11 The role of machinery design Machinery design is to formulate all engineering planEngineering in essence

3、is to utilize the existing resources and natural law to benefit humanityAs a major segment of engineerin，machinery design involves a range of disciplines in materials，mechanics，heat，flow，control，electronics and productionAlthough many high technologies are computerized and automated，and are rapidly

4、merged into Our daily life，machines are indispensable for various special work that is difficult or impracticable to be carried out by humanMoreover，machinery can significantly improve efficiency and quality of production，which is crucial in current competitive global market In the modern industrial

5、ized world，the wealth and living standards of a nation are closely linked with their capabilities to design and manufacture engineering productsIt can be claimed that the advancement of machinery design and manufacturing can remarkable promote the overall level of a countrys industrializationThose n

6、ations，who do not perform well in design and manufacture fields，are not competitive in world marketsIt is evident that several countries that used to be leaders in the design and manufacturing sectors until the l 960s and the 1 970s had，by the l990s，slipped back and lost their leadershipOn the contr

7、ary, our Country is rapidly picking up her position in manufacturing industry since the l 9 80s and is playing a more and more vital role in the global marketTo accelerate such an industrializing process of our country, highly skilled design engineers having extensive knowledge and expertise are nee

8、dedThat is why the course of machinery design is of great significance for students of engineering The course of machinery design is considerable different from those background subjects in science and mathematicsFor many students，it is perhaps one of their basic professional engineering courses con

9、cerned with obtaining solutions to practical problem sDefinitely these solutions must clearly represent an understanding of the underlying science，usually such an understanding may not be sufficient，empirical knowledge or engineering judgement has to be also involvedFurthermore，due to be professiona

10、l nature of this subject，most design problems may not have one right solutionNevertheless it is achievable to determine a better design from all feasible solutions 12 Machinery and components A state-of-the-art machine may encompass all or part of mechanical，electrical，control，sensor，monitoring and

11、lubricating subsystemsIn terms of the functions of those parts，the machine can also be viewed to be comprised of power，transmission，execution and controlmanipulation partsRegardless of the complexity, however，the major functional part may be still the mechanical systemFor convenience of analysis，the

12、 mechanical system can be decomposed int0mechanisms that are designed to execute some specific tasksAnd the mechanism can be further decomposed into mechanical componentsIn this sense，the mechanical components are the fundamental elements of machinery On the whole，mechanical components can be classi

13、fied as universal and special componentsBolts，gear and chains are the typical examples of the universal components which can be used extensively in different machines across various industrial sectorsTurbine blades，crankshaft and aircraft propeller are the examples of the special components，which Ca

14、n be used extensively in different machines across various industrial sectorsturbine blades，crankshaft and aircraft propeller are the examples of the special components，which are designed for some specific purposesIn addition to this，if a number of components are manufactured，assembled and even equi

15、pped as an individual system，egleaf spring set in a vehicle，it is also termed as a mechanical part A good machine definitely requires quality individual componentsThus，the design of components is very importantWhen designing a machine，on the other hand，engineers invariably find that requirements and

16、 constraints of its components are interrelatedAs a local portion，the component is expected to play a certain role on the machine and therefore must be appropriately restrained by the whole systemThe design of a gear drive in a speedreducer，for instance，depends upon not only the strength and stiffne

17、ss，but also the space available for the gears in the shaft and relation with other transmission driveThis means that the design of the mechanical components inevitably requires a whole view in the whole system Due to relationship between a machine and its components，the process of machinery design u

18、sually covers interconnected designs of machine，parts，and componentsAny modification and adjustment in one component may considerably affect the designs of other components or partsTo present the best possible design solution，the iteration of evaluation，analysis and optimization across all the proce

19、ss seem indispensable 13 Overview of machinery design This course is primarily concerned with the design of specific components of machines or mechanical systemsCompetence in this area is basic to the consideration and synthesis of complete machines and systems in subsequent courses and professional

20、 practiceIt Can be seen that even the design of a single bolt or spring needs the designers thorough understanding of the principles and methods of machinery design together with empirical information，good judgment and even a degre3e of ingenuity in order to produce the best product for the society

21、today It is natural that designing engineers give first consideration to the functional and economic aspects of new products or devicesMachinery design needs to ensure safety and reliability in a prescribed lifetimeTo address such a problem conventionally，the technical consideration of the mechanica

22、l component design is largely centered around two main areas of concerns：(1) strength-stiffness-stability criteria involving the bulk of a solid member and (2) surface phenomena including friction，lubrication，weal7，and environmental deteriorationHowever，in comparison with such relatively straightfor

23、ward computations as stress and deflection，the design determination of safety and reliability is likely to be an elusive and indefinite matter，complicated by psychological and sociological factorsIt must be kept in mind that safety and reliability are inherently relative to each other，and the value

24、judgments must be made with regard to tradeoffs between safety，reliability，cost，weight，and so forth On the other hand，a practical design needs to reflect clearly manufacturability and economy to make sure of the lowest cost as well as the least consumption of energy and materialsOtherwise，the produc

25、ts or devices designed will be of no further engineering or commercial interestsNowadays，the simultaneous considerations of manufacturing and assembly factors phases including design，manufacturing，inspection，as assembly and other is considered in such a parallel fashion that the quality and cost are

26、 best satisfied concurrently In addition to these traditionally technological and economic considerations fundamental to the design and development of mechanical components and systems，the modern engineers have become increasingly concerned with the broader considerations of sustainability，ecology，a

27、esthetics，ergonomics，maintainability，and overall quality of lifeIt is clear that a greater than ever engineering effort is being recently devoted to broader considerations relating to the influences of engineered products on people as well as on the environment The following is a list of general fac

28、tors for engineers to consider in the design process，which from a different viewpoint shows us a panoramic picture with regard to the design-related activities and tasks (1) Cost of manufacturingWill the selling price be competitive? Are there cheaper ways of manufacturing the machine? Could other m

29、aterials be used? Are any special tools，dies, jigs，or fixtures needed? Can it easily be inspected? Can the workshop produce it? Is heat treatment necessary? Can parts be easily welded? 第4页 Cost of operationAre power requirements too large? What type of fuel will be used? Will operation cost be less

30、expensive? (3) Cost of maintenanceAre all parts easily accessible? Are access panels needed? Can common tools be used? Can replacement parts be available? (4) Safety featuresIs a suitable factor of safety used? Does the safety factor meet existing codes? Are fuses，guards，andor safety valves used? Ar

31、e shear pins needed? Is there any radiation hazard? Any overlooked ”stress raiser”? Are there any dangerous fumes? (5) Packaging and transportationCan the machine be readily packaged for shipping without breakage? Is its size suitable to parcel post regulations, freight car dimensions，or trailer tru

32、ck size? Are shipping bolts necessary? Is its center of gravity in a desirable location? (6) LubricationDoes the system need periodic checking? Is it automatic? Is it a sealed system? (7) MaterialsAre chemical，physical，and mechanical properties suitable to its use? Is corrosion a factor? Will the ma

33、terials withstand impact? Is thermal or electrical conductivity important? Will high or low temperatures present any problem? Will design stress keep parts reasonable in size? (8) StrengthHave dimensions of components been carefully calculated? Have all the load cases be taken into account? Have the

34、 stress concentrations been carefully considered? Has the fatigue effect be computed? (9) KinematicsDoes it provide necessary motion for moving parts? Are rotational speeds reasonable? Could linkages replace cams? What will be the best choice，the belts，chains or gears? Is intermittent motion needed?

35、 (10) StylingDoes the color have eye appeal? Is the sharp desirable? Is the machine well proportioned? Are the calibrations on dials easily read? Are the controls easy to operate? (11) DrawingsAre standardized parts used? Are the tolerances realistic? Is the surface finish over-specified? Must the d

36、esign conform to any standards? (12) ErgonomicsHas the operator of the equipment been considered? Are the controls conveniently located to avoid operator fatigue? Are knobs，grab bars，hand wheels，levers，and dial calibrations of proper size to fit the average operator? 14 A general procedure of machin

37、ery design Whatever design tasks the designers are expected to complete，they always，consciously or unconsciously，follow the similar process which goes as follows： (1)Studies of feasibility After understanding the product functions，operational conditions，manufacturing constraints and key technologies

38、，go on to uncover existing solutions to some similar problems so as to clarify the design tasks，understand the needs，present the major functional parameters and evaluate design tasks，proposal of design aims，and feasibility analysis (2) Conceptual design of configuration According to the design of ta

39、sks and functional parameter，designs need to extensively search for various feasible configurations and alternativesFor convenience，usually，the system can be analyzed comprehensively by decomposing it into power sources，transmission and work mechanisms A great effort needs to be devoted to the analy

40、sis and synthesis of these different partsFor example，the power source may be selected from motor，engine and turbineEach power source may have a range of power and kinematical parameters Similarly, power trains may have numerous options available，egbelts，chains，gears，worm gears and many other drives

41、Obviously selecting an appropriate configuration would guarantee the Success of the whole design and the quality of the productsTo make a best possible decision，an iterative process is normally required to select，analyze，compare and evaluate different configurationsAt this stage，the goals involve sk

42、etching of configuration，determination of kinematical mechanisms，and evaluation of functional parameter(power and kinematics) (3)Detailed technical design Based on the design of configuration and parameters，a number of assembly and component drawings will be completed to reflect the detailed design

43、including kinematics，power，strength，stiffness，dynamics，stability，fatigue and SO onConsideration should also be given to manufacturing factors by presenting structural details，materials，and both geometric and dimensional tolerancesThis part of work will also be carried out in a repeated process in dr

44、awings，calculation，evaluation and modification until a best possible design is achievedThe goal at this stage is to complete assembly and component drawings，structural details，design calculations and detailed technical documentations (4)Modification of design After the design is completed，a prototyp

45、e is usually made for a more realistic physical assessment of the design qualityThis will help correct any drawback or fault that may be overlooked or neglected during the design processAt this stage，the goal is to correct the design imperfection，test the potential manufacturing or assembly flaws an

46、d refine /improve design 15 Contents and tasks of the course The course Machinery Design will cover the following contents： (1)Preliminariesthe fundamental principles of machinery and Components design，design theory，selection of materials，structure，friction ，wear and lubrication (2)Connectionsandjoi

47、ntsthreadfasteners，keys，rivets，welds，bonds and adhesive and interference joints (3)Transmissionscrews，chains，belts，gears，worms，bevelgears And helical gears (4)Shaftsystemrollingcontactbearings，sliding bearings，clutches，couplings，shafts，axles and spindles (5)Other part ssprings，housings and frame s The course centers on engineering design of mechanical components and is in a category of fundamental methodology and procedureIt is not feasible or realistic for the students to become involved in the detailed design considerations as