中英文翻译--机械工程设计-精品

1、. Mechanical engineering design 1. The meaning of design To design is to formulate a plan for the satisfaction of human need .in the beginning the particular need to the satisfied may be quite well-defined. Here are two examples of well-defined needs.1. How can we obtain large quantities of power cl

2、eanly, safely, and economically without using fossil fuels and without damaging the surface of the earth?2. This gear shaft is giving trouble; there have been eight failures in the last six weeks. Do something about it.On the other hand the particular need to be satisfied may be so nebulous and ill-

3、defined that a considerable amount of thought and effort is necessary in order to state it clearly as a problem requiring a solution. Here are two examples.1. Lots of people are killed in airplane accidents.2. In big cities there are too many automobiles on the streets and highways. This second type

4、 of design situation is characterized by the fact that neither the need nor the problem to be solved has been identified. Note, too, that the situation may contain many problems. We can classify design too. For instance: 1. Clothing design 7. Bridge design 2. Interior design 8. Computer-aided design

5、 3. Highway design 9. Heating system design 4. Landscape design 10. Machine design 5. Building design 11. Engineering design 6. Ship design 12. Process design In fact there are an endless number, since we can classify design according to the particular article or product or according to the professi

6、onal field.In contrast to scientific or mathematical problems, design problems have no unique answers; it is absurd, for example, to request the “correct answer” to a design problem, because there is none. In fact a “good” answer today may well turn out to be a “poor” answer tomorrow, if there is a

7、growth of knowledge during the period or if there are other structure or societal changes.Almost everyone is involved with design in one way or another, even in daily living, because problems are posed and situations arise which must be solved. Consider the design of a family vacation. There may be

8、seven different places to go, all the different distances from home. The costs of transportation are different for each, and some of the options require overnight stops on the way. The children would like to go to a lake or seashore resort. The wife would prefer to go to a large city with department

9、 store shopping, theatres, and nightclubs. The husband prefers a resort with a golf course. When these needs and desires are related to time and money, various solutions may be found. Of these there may or may not be one or more optimal solutions. But the solution chosen will include the travel rout

10、e, the stops, the mode of transportation, and the names and locations of resorts, motels, camping sites, or other away-from-home facilities. It is hard to see that there is really a rather large group of interrelated complex factors involved in arriving at one of the solutions to the vacation design

11、 problem. A design is always subject to certain problem-solving constraints. For example, two of the constraints on the vacation design problem are the time and money available for the vacation. Note, too, that there are also constraints on the solution, in the case above some of those constraints a

12、re the desire and needs of each of the family members. Finally, the design solution found might well be optimal. In this case an optimal solution is obtained when each and every family member can say that he or she had a good time. A design problem is not a hypothetical problem at all. Design has an

13、 authentic purposethe creation of an end result by taking definite acting or the creation of something having physical reality. In engineering the word “design ” conveys different meaning to different persons. Some think of a designer as one who employs the drawing board to draft the details of a ge

14、ar, clutch, or other machine member. Others think of design as the creation of a complex system, such as a communications network. In some areas of engineering the word design has been replaced by other terms such as systems engineering or applied decision theory. But no matter what words are used t

15、o describe the design function, in engineering it is still the process in which scientific the principles and the tools of engineeringmathematics, computers, graphics, and Englishare used to produce a plan which, when carried out, will satisfy a human need. 2. The phases of design The total design p

16、rocess is of interest to us, how does it begin? Does the engineer simply sit down at his or her desk with a blank sheet of paper and jot down some ideas? What happens next? What factors influence or control the decisions, which have to be made? Finally, how does this design process end? The complete

17、 process, from start to finish, is often outlined as in Figure. The process begins with a recognition of a need and a decision to do something about it, after many iterations, the process ends with the presentation of the plans for satisfying the need, we should examine these steps in the design pro

18、cess in detail.3. Mechanical engineering designMechanical design means the design of things and system of a mechanical naturemachines, products, structures, devices, and instruments. For the most part, mechanical design utilizes mathematics, the materials sciences, and the engineering mechanical sci

19、ence.Mechanical engineering design includes all mechanical design, but it is a broader study because it includes all the disciplines of mechanical engineering, such as the thermal-fluids sciences, too. Aside from the fundamental sciences that are required, the first studies in mechanical engineering

20、 design are in mechanical design, and hence this is the approach taken in this book.4. Design Process and StagesMechanical design is either to formulate all engineering plan for the satisfaction for the specified need or to solve an engineering problem. It is vast field of engineering technology whi

21、ch not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but all considers the various factors involved in the manufacture, marketing and use of product. Mechanical design involves a range of disciplines in materials, mechanics, he

22、at, flow, control, electronics and production.Mechanical design should be considered to be an opportunity to use innovative talents to envision a design of a product, to analyze the system and then make sound judgments on how the product is to be manufactured. It is important to understand the funda

23、mentals of engineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used to provide all the correct decisions required to produce a good design. On the other hand, any calculations must be done with the utmost care and precision. For example, if a

24、 decimal point is misplaced, an otherwise acceptable design may not function.Mechanical design may be simple or enormously complex, easy or difficult, mathematical or nonmathematical, it may involve a trivial problem or one of great importance. Good design is the orderly and interesting arrangement

25、of all idea to provide certain results and effects. A well-designed product is functional, efficient, and dependable. Such a product is less expensive than a similar poorly designed product that does not function properly and must constantly be repaired.People who perform the various functions of me

26、chanical design are typically called designers, or design engineers. Mechanical design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, manu

27、facturing processes. The designer must first carefully define the problem, using an engineering approach, to ensure that any proposed solution will solve the right problem. It is important that the designer begin by identifying exactly how he or she will recognize a satisfactory alternative, and how

28、 to distinguish between two satisfactory alternatives in order to identify the better. So industrial designers must have creative imagination, knowledge of engineering, production techniques, tools, machines, and materials to design a new product for manufacture, or to improve an existing product. I

29、n the modern industrialized world, the wealth and living standards of a nation are closely linked with their capabilities design and manufacturing engineering products. It can be claimed that the advancement of mechanical design and manufacturing can remarkably promote the overall level of a country

30、s industrialization. Many countries are playing more and more vital role in the global manufacturing industry. To accelerate such an industrializing process, highly skilled design engineers having extensive knowledge and expertise are needed. 5. Mechanical design processProduct design requires much

31、research and development. Many concept of an idea must be studied, tried, refined, and then either used or discarded. Although the content of each engineering problem is unique, the designers follow the similar process to solve the problems. The complete process is often outlined as in figures. The

32、design process usually begins with a specification of a solution. We sometimes allude to a design cycle, but the process may contain a design cycle plus design implementation, which involves actual production based upon the design. The design cycle can involve the original thoughts, sketches, and kn

33、owledge that in the specification stage produce engineering drawings. Computer-aid design is now employed to implement a cycle in which various designs or design ideas may be tested or simulated.6. Contents of Mechanical Design Mechanical design is an important technological basic course in mechanic

34、al engineering education. Its objective is to provide the concepts, procedures, data, and decision analysis techniques necessary to design machine elements commonly found in mechanical devices and systems; to develop engineering students competence of mechanical design that is the primary concern of

35、 machinery manufacturing and the key to manufacturing good products.Mechanical design covers the following contents:1Provides an introduction to the design process, problem formulation, safety factors. 2Reviews the material properties and static and dynamic loading analysis, including beam, vibratio

36、n and impact loading.3Reviews the fundamentals of stress and defection analysis.4Introduces static failure theories and fracture-mechanics analysis for static loads.5Introduces fatigue-failure theory with the emphasis on stress-life approaches to high-cycle fatigue design, which is commonly used in

37、the design of rotation machinery.6Discusses thoroughly the phenomena of wear mechanisms, surface contact stress, and surface fatigue.7Investigates shaft design using the fatigue-analysis techniques.8Discusses fluid-film and rolling-element bearing theory and application.9Gives a thorough introductio

38、n to the kinematics, design and stress analysis of spur gears, and a simple introduction to helical, bevel, and worm gearing. 10Discusses spring design including helical compression, extension, and torsion springs.11Deals with screws and fasteners including power screw and preload fasteners.12Introd

39、uces the design and specification of disk and drum clutches and brakes.机械工程设计1. 设计的意义 设计是制定一项计划，以便满足人类的需要。在开始的特别需要的满足可能相当明确。这里有两个例子明确界定的需要。 1. 我们怎样才能获得大量的电力干净，安全，经济上不使用化石燃料和不破坏了地球表面的？ 2. 这是给齿轮轴麻烦;有8个失误，在过去6个星期。做点什么。 另一方面，尤其需要得到满足可能是这样模糊不清和不明确，有相当数量的思路和努力是必要的，以国家显然是一个问题需要解决。这里有两个例子。 1 .很多人死于飞机事故。 2 .

40、在大城市有太多汽车的街道和高速公路。 这第二种类型的设计局势的特点是一个事实，即既不需要也不是要解决的问题已被确定。请注意，也这种情况可能包含许多问题。 我们也可以分类设计。例如： 1 .服装设计 7 .桥梁设计 2 .室内设计 8 .计算机辅助设计 3 .公路设计 9 .供暖系统设计 4 .景观设计 10 .机械设计 5 .建筑设计 11 .工程设计 6 .船舶设计 12 .工艺设计 事实上有一个无休止一些，因为我们可以把设计的特定物品或产品或根据专业领域。 相反，科学或数学问题，设计独特的问题没有答案，这是荒谬的，例如，要求“正确答案”的设计问题，因为没有人反对。事实上是一个“良好”的回答

41、今天很可能成为一种“穷人”的答案明天，如果有一个增长知识，或在此期间如果有其他结构或社会的变化。 几乎每个人都参与了设计一种或另一种方式，即使在日常生活中，由于提出的问题和情况时，必须予以解决。考虑设计一个家庭度假。可能有7个不同的地方去，所有不同的距离回家。运输费用的不同，每一个，而有些选项需要通宵站的道路上。孩子们要到一个湖泊或海边度假胜地。妻子宁愿去大城市的百货商店购物，剧院，和夜总会。丈夫喜欢度假的一个高尔夫球场。当这些需要和愿望是与时间和金钱，各种解决方案，可能会发现。这些有可能是也可能不是一个或多个最优解。但是，该解决方案将包括选择旅行路线，站，运输方式，以及姓名和地点度假村，汽车

42、旅馆，露营地，或其他以外，来自家庭的设施。这是很难看到，确实是一个相当大组相互关联的复杂因素，在达成一个解决办法，度假设计问题。 外观设计一直受到某些解决问题的制约。例如，有两个制约因素的度假设计问题是时间和金钱用于度假。请注意，也也有限制的解决方案，如果上述的一些制约因素的愿望和需要，每个家庭成员。最后，设计解决方案，发现很可能是最佳的。在这种情况下，一个最佳的解决方案时，得到的每一个家庭成员可以说，他或她的好时机。设计的问题不是一个假设的问题。设计有一个真实的目的，建立一个最终的结果，采取一定的代理或建立了具有物理现实。在工程中的“设计” ，传达不同的意义，不同的人。有些人认为的是谁设计的

43、图板采用草案的细节，齿轮，离合器，或其他机器的成员。其他人认为的设计，建立一个复杂的系统，如通信网络。在一些地区的工程设计一词取代了其他条款，如系统工程或实施决策理论。但不管用什么词来描述设计的功能，在工程中仍然是这一进程中，科学的原则和工具的工程，数学，计算机，图形和英文，是用于生产的计划，当进行出，将满足人类的需要。 2. 各阶段的设计 总的设计过程是对我们的利益，它是如何开始的？是否工程师只是坐下来他或她的办公桌，一张空白的纸张，并记下一些想法？接下来该怎么做？什么因素影响或控制的决定，必须做的？最后，请问这个设计过程结束？ 全过程，从开始到结束，往往是在图概述。 2-2-1 。这一进程

44、始于承认需要和一项决定，做些事，经过多次反复，这一进程结束时提出的计划，为满足需要，我们应该研究这些措施在设计过程中的细节。 3. 机械工程设计 机械设计手段设计的东西，系统的机械性质的机器，产品，结构，设备和仪器。在大多数情况下，机械设计采用数学，材料科学和工程机械的科学。 机械工程设计包括所有机械设计，但它是一个更广泛的研究，因为它包括了所有的学科机械工程，如热流体科学，也。除了基本的科学所需要的，首先研究了机械工程设计中的机械设计，因此这是在这本书采取的办法。 4. 设计过程和阶段机械设计或是制订所有工程计划的满意度为指定的需要或解决工程问题。这是广大工程技术领域，不仅关注自己的原始构想的产品而言，其