材料选择外文文献翻译、中英文翻译

1、 附译文二Selecting MaterialsWe are surrounded by materials and we rarely think about how thesematerials are selected. Why was your desk made of solid wood, plywood, orplastic-laminated particleboard? Why have so many plastics replaced steel andzinc in automobiles? What is the controversy about using foa

2、med polystyreneplastic to package fast food?While you might take granted the materials that make up your products,you can be sure that the designers did not. People who design homes, cars,aircraft, clothing, furniture, and other products or systems devote a lot ofattention to the selection of the ma

3、terials they use. Material selection might makeor break a company. But how do the designers make that selection to arrive atthe best material? What selection criteria are most important?The Ideal MaterialWhat is an ideal material? Among other characteristics, we can list thefollowing for the ideal m

4、aterial:1. Endless and readily available source of supply2. Cheap to refine and produce3. Energy efficient4. strong, stiff, and dimensionally stable at all temperatures5. Lighweight6. Corrosion resistant7. No harmful effects on the environment or people8. Biodegradable9. Numerous secondary usesIt is

5、 a very complex process for the designer to find the ideal material for aspecific product.Obstacles to ChangeSwitching from traditional materials such as steel and concrete to newermaterials such as plastic-based composites seem a simple, straightforwardapproach for the contemporary designer. The ne

6、wer materials are often superior,but sometimes there are complications. Often, lack of experience with newmaterials causes hesitation by designers. Departures from tried-and-truematerials may be costly. It requires time before both designers and fabricatorsgain sufficient experience to make products

7、 or systems. This problem isexacerbated when human life might be in jeopardy, such as when designing foraircraft. Consequently, new materials and processes are usually slower to enterthe marketplace than might be expected. These issues are all a part ofengineering problem solving. Materials selectio

8、n is a problem-solving issue thatrequires an algorithm for its solution.Algorithm for Materials Selection Engineering requires clearly stated, unambiguous steps for problem solving.Algorithms are well-defined methods for solving specific problems. Computerprograms are written after an algorithm has

9、been developed to lie out clearly thesteps that the program is to solve. For example, you could write a simplealgorithm to calculate the strength required of a light pole to withstand thepushing forces from a light fixture. A much more complex algorithm would berequired to select a piston connecting

10、 rod for an internal-combustion engine. Thefirst problem requires only the selection of a material of suitable size/strength tohold up the light fixture, and almost any material would suffice as long as it wassufficiently strong and pleasing to the user. On the other hand, a connecting rodwill under

11、go many types of mechanical stress, ranging from compressive totensile to torsional to gravity forces, in addition to thermal stress from thecombustion chamber. How does the designer match component requirementswith available materials?Selection ToolsTo aid in the creation of materials selectionalgo

12、rithms, databases must be available to answer questions on materialsuitability. A materials database involves tables listing properties of materials,such as tensile strength, hardness, corrosion resistance, and the ability towithstand heat. Thousands of reference books are available with such data.M

13、uch of these data are computerized to allow easier access. Certain graphicaltechniques aid the designer in materials selection.Properties of MaterialsPeriodicals can provide current data andperformance criteria that involve that involve structural materials:1. Strength (tensile, compressive, flexura

14、l, shear, and torsional)2. Resistance to elevated temperatures3. Fatigue resistance (repeated loading and unloading)4. Toughness (resistance to impact)5. Wear resistance (harddness)6. Corrosion resistanceSuch publications present values for the performance criteria (properties)for metals, polymers,

15、and ceramics, with updates on newer materials such asaramid fibers, zinc aluminum alloys, and super alloys. Various periodicals haveannual materials selectors that provide general information on properties for along list of materials.The many tables, covering representative materials, provide genera

16、l data onproperties for a simple comparison. Selection of specific materials requires manymore detailed specifications. General databases from handbooks will providemuch detail, but the final selection often requires that material manufacturerssupply their own properties database for their product l

17、ines. While databases areimperative in the initial selection steps, there are other factors that complicatematerials selection.Materials SystemsMaterials rarely exist in isolation without interacting with other materials. Rather, a combination of materials is selected tocomplement one another. In a

18、successful materials system, each component iscompatible with the others while contributing its distinctive properties to theoverall characteristics of the system of which it is a part. A state-of-the arttelephone is a good example. The casing might be a tough ABS plastic, whichhouses a microchip (a

19、 solid-state ceramic device) that provides memory andsound-transmission capabilities. Copper leads join the circuitry together. Theremight be a battery and a ceramic must light-emitting diode to show when thebattery is low. The acid in the battery must be isolated to prevent corrosion, andthe copper

20、 leads must be insulated so that they do not short out. Each componentis made of materials that meet the demands of the physical and chemicalenvironment normally encountered when using the system.Additional Selection CriteriaExisting specifications have a lot ofinfluence on the choice of material. T

21、hese specifications or “standards” are usedwhen redesigning an improved model of the product. When thematerials-selection algorithm results in selection of a new material, I might notbe covered by current specifications from standardization agencies. Theconditions of safety must be met by those invo

22、lved in the manufacture or use ofgoods and services. It might take the new material or they might not approve itsuse.Availability is another concern of the designer. Will the material be easilyavailable in the quantities and sizes required by the production demands? Inaddition, will it be available

23、in the shapes required? Aluminum extrusions, forexample, are available in many varieties of standard shapes, such as round, oval,and square tubing. In the past, designers were limited to existing materials suchas metal alloys, woods, or concrete. Now, it is possible to start from scratch at thesynth

24、esis stage to have materials engineers design a materials system to provideproperties to meet the expected needs.Processibility, the ease with which raw materials can be transformed into afinished product, is of paramount concern. Much of the current focus is onlow-energy processing. Companies may h

25、ave difficulty processing the newmaterial on existing equipment. Can they afford to invest in new equipment?Today, the reverse question is usually asked: Can we afford to use the newmaterial and process? If we do not, the competition might make the change andrun us out of business with their superio

26、r product. Many new technologies arenow available.Quality and performance are two aspects that achieve consumer satisfaction.The high cost of most durable goods and the competition for customeracceptance has resulted in extended warranties. Materials selection must ensurethat parts will not rust, br

27、eak under repeated stress, or fail to perform in anyother way for the predicted service life of the product.Consumer acceptance includes many factors beyond excellent quality andhigh performance; there are also societal aspects. Society as a whole as well as governmental agency is requiring a closer

28、 look at manufactured products. Anyproduct has to be considered in terms of its total life cycle. What are the resultsof the processing methods? Are polluting gases being released into theenvironment, or are toxic metals and chemicals being flushed into our rivers andstreams? During use, does the pr

29、oduct safeguard our health? At the end of theproducts useful life, how can it be disposed of safely? Municipal solid waste is ahidden product cost that we pay in the form of higher taxes and poorer quality oflife. Fast-food restaurant chains moved away from polystyrene packages becausethe public fel

30、t these plastic containers were more harmful to the environmentthan paper packaging. Soft-drink manufacturers are moving toward reusableplastic bottles.Design for disassembly has become a theme in much of product design bymajor corporations. Europe, which has a higher degree of ecological concern, h

31、asled the way. With the desire to facilitate recycling, manufacturers of smallappliances and durable goods are establishing procedures to ensure thatproducts can be broken into components for easy sorting prior to recycling.Among the procedures are reducing the variety of plastics, adding labels top

32、lastics for easy identification of plastic type, and eliminating screws andadhesives so that parts will disassemble easily.One of the latest software programs is designed specifically to makeproducts easier to fix. Known as Design for Service, this program takes its placealongside previous software

33、programs called Design for Assembly and Design forManufacturability. This new program helps product designers consider repairissues early in the design stage. Objectives of the program include makingrepairs less costly and extending the functioning life of products. Environmentalissues such as recyc

34、ling are directly addressed by this new computer software,which may have customers fixing products rather than tossing them out. Inaddition, this software augments previous software that addresses the need fordisassembly of a product for whatever reason.More often than not, cost is the primary selec

35、tion criterion that willdetermine the final choice of material. In other words, if several materials havethe specified physical, mechanical, and chemical properties, and are suitable forthe processing technique selected, the lower-cost materials would be the logicalchoice. Determining cost is not as

36、 simple as it may seem. For example, a varietyof plastics, including PET (poly ethylene terephthalate) and HDPE (high-densitypolyethylene), have replaced glass as containers for soft drinks, milk and juices.Although the initial cost of plastic may be greater, the plastic bottles providesaving due to

37、 their toughness (less breakage) and the saving in shipping (PETand HDPE are much lighter than glass bottles).Product liability is civil (as opposed to criminal) liability of the manufacturer toan ultimate user for injury resulting from a defective product. Caveat emptor (letthe buyer beware) was on

38、ce the rule. Today, numerous liability laws are in effect.For those involved in materials selection in the design process, the trend is forcourts and juries to identify members of the design team as being responsible for some fault in a product-liability action. Therefore, it is imperative to obtain

39、 anduse the latest information about materials selection, particularly long-termcharacteristics of materials. 材料选择我们是被材所包围并且很少思考我们是如何选择材料的。为什么你的桌子用木板做的，用三合板做的或用塑胶层压碎料板？为什么有这么多的塑料代替钢和锌在汽车工业中。对使用泡沫聚苯乙烯塑料来包装快餐的争议是什么？当你认为制作你的产品的材料，你就能确定设主者所不会的。那些设计家庭，汽车，航空器，服装，家具和其它的产品或系统的设计师都会把很多的心关注在这材料的选择上。材料的选择可能需要很

40、多的选择。但这设计师要怎样选择材料才能最好程度地利用材料。什么选择标准是最好的呢？理想材料理想的材是什么呢？我们能列举出以下一些典型性的材料：1无穷尽的和有备用的可获得的资源来源。2生产和提炼的成本低廉。3能量效率高4强，硬和尺寸稳定在任何温度下5轻便6抗腐蚀7对人和环境无有害影响8可生物降解9可多次利用为具体的产品找一个理想的材料是非常复杂的过程对于设计师来说。故障的变化从像钢这样的传统材料转换到新的像塑料基复合材料这样的材料看起来很简单，直接的，接近这同时期的设计者。越新的材料往往越优越，但有时候会很复杂。通常，由于对新材料缺乏经验而使设计师很犹豫。从试真材料上分离出来可能会要很多代价的。

41、它需要时间在设计师和制造者获得足够的经验使变得舒适的用新材料和相关的过程的需要来做产品和系统。当人的生命是处在像设计航空器这样的危险中时它可能就会加剧恶化。因此，新材料处理过程通常是更慢地进入市场比预期的。这些争端都是工程问题要解决的问题。材料选择就是一个需要算法演译来解决的争议。材料选择的算法工程需要确切的说明，清晰的步聚来解决问题。算法就是一个用来解决具体问题的比较完善的定义。计算机程序是在算法形成之后来清晰地罗列出这程序要解决的问题。例如，你可以写一个简单的算法来计算一根轻杆要支撑一个来自于轻固定设备的推力所需的强度。要为内燃机选择一个活塞连杆就需要更多更复杂的算法。第一个问题就是要选择

42、合适的大小 /强度来撑起这轻设备，和大多数材料都会需要的只要它有足够的强度和使用起来较好。另外一方面，连杆将经受很多种的机械应力，从压力到拉伸到扭转到重力级别。设计师将怎样用可获得的材料来匹配零部件？工具选择为了帮助材料选择算法的创造，数据单元必须是可用的对于 回答材料适用性这一块。一个材料数据库需要表来罗列材料的特性，比如拉伸强度，硬度，抗腐蚀性和耐热性。成千上万种参考书都是可以得到这样的数据的。这些数据的大多数都已经是电脑化了以便于更容易来访问。某些算法技能帮助了设计师来选择材料。材料的特性杂质能够提供当前的数据和所需的材料的使用标准：1强度（拉伸，压缩，弯曲，剪切和扭转）2耐温升3抗疲劳

43、性（重复地装载和卸载）4刚度（抗冲击）5耐磨性（硬度）6抗腐蚀性这个出版物提供这个执行标准为金属，聚合物和陶瓷，并更新新材料像想到此纤维，锌铝合金和更优秀的合金。各个时期都会有一年一次的材料选择器来提供总一长串材料特性信息列表。这么多表，含盖了典型的材料，提供了总的数据在材料的特性方面的简单比较。选择具体的材料需要许多详细的说明书。来自于手册的数据库将提供更详细的数据，但最后的选择通常需要材料生产商为他们自己的产品生产线提供自己的特性数据库。当数据库是必须的在最初的材料选择上，那将会有其它因素使材料选择更复杂。材料系统材料几乎是独立存在的而不与其它材料相互联系。而且，一个材料的选择与另一个相互补充。在这成功的材料中，当它的独特性能促进这系统的一部分特性时它将与其它部件相容合。这艺术品就是一个很好的例子。这罩壳可能是结实的丙烯腈-丁二烯-苯乙烯塑料，即可以用来封装芯片以提供内存和完好的传输性能。铜、铅和电路板结合在一起。可能有一个电池和陶瓷光束真空管来显示这电池是低的。酸在电池内必须是独立地以防止腐蚀，和铜和铅必须