外文翻译---机械设计简介.docx

外文资料introduction to mechanical designmechanical design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. it is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product. people who perform the various functions of mechanical 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, strength of materials and manufacturing processes.as stated previously, the purpose of mechanical design is to produce a product which will serve a need for man. inventions, discoveries and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. it should be recognized, therefore, that a human need must be identified before a particular product is designed.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 fundamentals 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 calculation made must be done with the utmost care and precision. for example, if a decimal point is misplaced, a otherwise acceptable design may mot function.good designs require trying mew ideas and being willing to take a certain amount of risk, knowing that if the mew idea does not work the existing method can be reinstated. thus a designer must have patience, since there is no assurance of success for the time and effort expended. creating a completely new design generally requires that many old and well-established methods be thrust aside. this is not easy since many people cling to familiar ideas, techniques and attitudes. a design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated.new designs generally have “bugs” or unforeseen which must be worked out before the superior characteristics of the new designs can be enjoyed. thus there is a chance for a superior product, but only at higher risk. it should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change. during the beginning stages of design, creativity should be allowed to flourish without a great number of constraints. even though many impractical ideas may arise, it is usually easy to eliminate then in the early stages of design before firm details are required by manufacturing. in this way, innovative ideas are not inhibited. quite often, more than one design is developed, up to the point where they can be compared against each other. it is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise.psychologists frequently talk about trying to fit people to the machines they operate. it is essentially the responsibility of the engineer to strive to fit machines to people. this is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum.another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they ate to be incorporated. communicating the design to others is the final, vital step in the design process. undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unable or unwilling to explain their accomplishments to others. presentation is a selling job. the engineer when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted. basically, there ate only three means of communication available to us. these are the written, the oral, and the graphical forms. therefore the successful engineer will be technically competent and versatile in all three forms of communication. a technically competent person who lacks ability in any one of these forms is severely handicapped. if ability in all three forms is lacking, no one will ever know how competent that person is! the competent engineer should not be afraid of the possibility of not succeeding in a presentation. in fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. there is a great deal to learn from a failure, and the greatest gains ate obtained by those wiling to risk defeat. in the final analysis, the real failure would lie in decoding not to make the presentation at all. to communicate effectively, the following questions must be answered:1、does the design really serve a human need?2、will it be competitive with existing products of rival companies?3、it is economical to profit?4、can it be readily maintained?5、will it sell and make a profit? only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed only with initial affirmative answers. the design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings. quite often, a problem will occur during the manufacturing cycle. it may be that a exchange is required in the dimensioning or tolerancing of a part so that it can be more readily produced. this falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. in other cases, a deficiency in the design may appear during assembly or testing just prior to shipping. engineering design is a systematic process by which solutions to the needs of humankind are obtained. the process is applied to problems (needs) of varying complexity. for example, mechanical engineers will use the design process to find an effective, efficient method to convert reciprocating motion to circular motion for the drive train in an internal combustion engine; electrical engineers will use the process to design electrical generating systems using falling water as the power source; and materials engineers use the process to design ablative materials which enable astronauts to safely the earths atmosphere.the vast majority of complex problems in todays high technology society depend for solution not on a single engineering discipline, but on teams of engineers, scientists, environmentalists, economists, sociologists, and legal personnel. solutions are not only dependent upon the appropriate applications of technology but also upon public sentiment, government regulations and political influence. as engineers we are empowered with the technical expertise to develop new and improved products and systems, but at the same time we must be increasingly aware of the impact of our actions on society and the environment in general and work conscientiously toward the best solution in view of all relevant factors.design is the culmination of the engineering educational process; it is the salient feature that distinguishes engineering from other professions. a formal definition of engineering design is found in the curriculum guidelines of the accreditation board for engineering and technology (aent). aben accredits curricula in engineering schools and derives its membership from the various engineering professional societies. each accredited curriculum has a well-deigned design component which falls within the aben guideline. the aben statement on design reads as follows: engineering design is the process of devising a system, component, or process to meet desired needs. it is a decision making process (often iterative ), in which the basic sciences, mathematic, and engineering sciences are applied to convert resources optimally to meet a stated objective. among the fundamental elements of the design process are the establishment of objectives and criteria, synthesis, analysis, construction, testing, and evaluation. the engineering design component of a curriculum must include most of the following features: development of student creativity, use of open-ended problems, development and use of modern design theory mad methodology, formulation of design problem statements and specifications, consideration of alternative solutions, feasibility considerations, production processes, concurrent engineering design, and detailed system descriptions. further, it is essential to include a variety of realistic constraints such as economic factors, safety, reliability, aesthetics, ethics, and social impact.if anything can be said about the last half of the twentieth century, it is that we have had an explosion of information. the amount of data that can be uncovered on most subjects is overwhelming. people in the upper levels of most organizations have assistants who condense most of the things that they must read, hear, or watch. when you begin a search for information, be prepared to scan many of your sources and document their location so that you can find them easily if the date subsequently appear to be important.some of the sources that are available include the following: 1、 exiting solutions. much can be learned from the current status of solutions to a specific need if actual products can be located, studied and, in some cases, purchased for detailed analysis. an improved solution or an innovative new solution new solution cannot be found unless the existing solutions are thoroughly understood.2、 your library. many universities have courses that teach you how to use your library. such courses are easy when you compare them with those in chemistry and calculus, but their importance should not be underestimated. there are many sources in the library that can lead you to the information that you are seeking. you may find what you need in an index such as the engineering index. there are many other indexes that provide specialized information. the nature of your problem will direct which ones may be helpful to you. dont hesitate to ask for assistance from the librarian. you should use to advantage the computer databases found in libraries and often available through cd-rom technology.3、professional organizations. the american society of mechanical engineers is a technical society that will be of interest to students majoring in mechanical engineering. each major in your college is associated with not one but often several such societies. the national society of professional engineers is an organization that most engineering students well eventually join, as well as at least one technical society such as the society of manufacturing engineers, the american society of civil engineers (asce), or any one of dozens that serve the technical interests of the host of specialties with which professional practices seem most closely associated. may engineers are members of several associations and societies.4、trade journals. they are published by the hundreds, usually specializing in certain classes of products and services. money and economics are part of engineering design and decision making. we live in a society that is based on economics and competition. it is no doubt true that many good ideas never get tried because they are deemed to be economically infeasible. most of us have been aware of this condition in our daily lives. we started with our parents explaining why we could not have some item that we wanted because it cost too much. likewise, we will not put some very desirable component into our designs because the value gained will not return enough profit in relation to its cost. industry is continually looking for new products of all types. some are desired because the current product is not competing well in the marketplace. others are tried simply because it appears that people will buy them. how do manufacturers know that a new product will be popular? they seldom know with certainty. statistics is an important consideration in market analysis. most of you will find that probability and statistics are an integral part of your chosen engineering curriculum. the techniques of this area of mathematics allow us to make inferences about how large groups of people react based on the reactions of a few.中文翻译机械设计简介机械设计是为了满足人类需要而制定出的新产品或者改进旧产品时对科学与技术的应用。 它是工程技术的一个巨大领域,这个领域不仅关注原先这种产品的尺寸，形状以及构造方式， 而且考虑涉及这种产品的制造，销售和使用的其它各方面的因素。进行机械设计的各种各功能的人们被通常叫为设计者或者设计工程师。 机械设计基本上是一次创造活动。 然而， 除富有创新精神之外， 一位设计工程师也必须在机械制图，运动学，力学，材料工程，材料强度和制造工艺有一定的背景知识。精确的说，机械设计的目的就是为了满足人们的需求。 发明，创造和科学知识它们自己可能不能让人获益； 但是只要他们合并在一起并设计产品，其益处就会被得到。因此，在一种特别的产品被设计之前，人的需求必须被鉴定，这一点应该被认识到。机械设计应被视为一个机会，利用创新人才的设想设计一个产品，分析系统，然后就如何制造产品作出正确的判断。对工程基础的理解而不是仅仅记住事实和方程式，这一点是很重要的。 没有哪个事实或方程式能单独提供要求生产一种好设计的全部的正确的决定。 另一方面，任何计算必须得最大限度小心和精密。 例如，一个小数点放错，就有可能得不到所要设计得到的结果。好的设计应该需要尝试新的方法并且愿意承担一定的风险，知道如果新想法不起作用，这种现有的方法可能被重新使用。由于为了成功所付出的时间以及努力是不能保证的，因此一个设计者必须要有耐心。创造一个完全新的设计一般要求很多旧的以及被建立起来的方法来推动。这并不容易因为很多人坚持旧的想法，技术和态度。设计工程师要不断寻找方法，以改善现有的产品，并且决定哪些旧的、已被证明的概念须要采纳，哪些新的、未曾尝试的想法应该被包刮进来。在那些新设计的优势特性可以被享有之前,新设计一般有缺陷或者一些未预见的缺点。因此，有机会，提供优异的产品，但只有在较高的风险下。应该强调指出，如果一个设计并不需要激进的新方法，这种方法不应适用而仅仅是为了改变。在设计的开始阶段，创造性应该被提倡而没有许多限制条件。 即使很多不实用的想法可能出现，在稳定的细节生产被要求之前，这些在设计早期通常是容易消除的。以这种方法，富创新精神的想法不被抑制。 经常，不止一种设计被提出，甚至到他们可能对彼此被进行比较的方面。 这是完全可能的：最终被接受的设计将可能使用被拒绝的设计之中的一个想法。心理学家经常谈论努力使他们操作的那些机器适合人。努力使机器适应人基本上是工程师的责任。这不是一项容易的任务,因为真的没有人能够把某一个生产尺寸加工到最优化的程度。另一个要点是：一位设计工程师必须能把想法传达给其他人，当他们的想法可以被采纳时。 把设计思想传达给其它人是最后环节，也是在设计过程里的至关重要的步骤。无疑很多重要的设计，发明和有创造性的作品被人们所不认同，仅仅是因为那些创始人不能或者不愿意对其它人解释他们的成就。 赠送是一个出售的工作。 当提出一个新的解决方案，管理或者监督的人的方法时，工程师， 正试图出售或者向他们证明这个解决办法是更好的。 除非这能被成功操作，否则关于获得这个解决办法所花费的时间和努力基本上是浪费的。基本上，那里只有我们可用的3个通信手段。 它们是写，口头，以及图表的形式。 因此成功的工程师将精通这3 种交际方式的能力。缺乏其中任何一个交际能力的一个技术人员就相当于严重残疾。如果全部3个交际能力都缺乏的话，没有人知道此人是多么有能力！有能力的工程师不应该害怕推荐自己不成功的可能性。实际上，偶然的失败应该被期望，因为失败或者批评好像伴随每个真的有创造性的想法。 有许多都是从失败中获悉，巨大收获都是从那些冒险获得的。归根到底，真正的失败将在于根本不会做推荐自己。 为了有效地交流，下列问题必须被回答：(1)这设计真的能服务人需要吗？ (2)它将与现有的竞争公司的产品竞争吗？ (3)获益是实惠的吗？ (4)它能被比较容易的保持吗？ (5)它将能被出售并且赢利吗？ 只有时间能提供上述问题的正确的答案，但是产品应该被设计，只用最初肯定的答案生产并且销售。设计工程师也必须通过使用细节和装配图多沟通定稿设计到生产。经常，一个问题将在生产的循环期间产生。这可能是在一个部分的定尺寸或者加工过程中所要求一次交换，以便它能够被更容易生产。这在被设计工程师批准的工程变化的种类方面下降，以便产品功能将不被相反影响。 在其他情况里，在设计过程中的一种缺陷可能在装运之前的装配或检测测试期间出现。工程设计是一个系统的过程，其中的解决方案是为了满足人类需要而得到的。进程是不同的复杂性的问题（需求）的应用。例如，机械工程师，将利用设计过程中，以找到一个有效率的方式转换成往复运动，在一个内部内燃机以圆周运动来驱动列车;电气工程师在使用过程中，以设计电动发电机系统使用，水位下降为能源;材料工程师使用过程中，以设计烧蚀材料，使宇航员平安返回地球的大气层。在今天的高科技社会,绝大多数的复杂问题赖以解决的方案不仅仅取决于单一的工程学科，而且还取