材料選擇外文文獻(xiàn)翻譯、中英文翻譯

1、 附譯文二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. 材料選擇我們是被材所包圍并且很少思考我們是如何選擇材料的。為什么你的桌子用木板做的，用三合板做的或用塑膠層壓碎料板？為什么有這么多的塑料代替鋼和鋅在汽車(chē)工業(yè)中。對(duì)使用泡沫聚苯乙烯塑料來(lái)包裝快餐的爭(zhēng)議是什么？當(dāng)你認(rèn)為制作你的產(chǎn)品的材料，你就能確定設(shè)主者所不會(huì)的。那些設(shè)計(jì)家庭，汽車(chē)，航空器，服裝，家具和其它的產(chǎn)品或系統(tǒng)的設(shè)計(jì)師都會(huì)把很多的心關(guān)注在這材料的選擇上。材料的選擇可能需要很

40、多的選擇。但這設(shè)計(jì)師要怎樣選擇材料才能最好程度地利用材料。什么選擇標(biāo)準(zhǔn)是最好的呢？理想材料理想的材是什么呢？我們能列舉出以下一些典型性的材料：1無(wú)窮盡的和有備用的可獲得的資源來(lái)源。2生產(chǎn)和提煉的成本低廉。3能量效率高4強(qiáng)，硬和尺寸穩(wěn)定在任何溫度下5輕便6抗腐蝕7對(duì)人和環(huán)境無(wú)有害影響8可生物降解9可多次利用為具體的產(chǎn)品找一個(gè)理想的材料是非常復(fù)雜的過(guò)程對(duì)于設(shè)計(jì)師來(lái)說(shuō)。故障的變化從像鋼這樣的傳統(tǒng)材料轉(zhuǎn)換到新的像塑料基復(fù)合材料這樣的材料看起來(lái)很簡(jiǎn)單，直接的，接近這同時(shí)期的設(shè)計(jì)者。越新的材料往往越優(yōu)越，但有時(shí)候會(huì)很復(fù)雜。通常，由于對(duì)新材料缺乏經(jīng)驗(yàn)而使設(shè)計(jì)師很猶豫。從試真材料上分離出來(lái)可能會(huì)要很多代價(jià)的。

41、它需要時(shí)間在設(shè)計(jì)師和制造者獲得足夠的經(jīng)驗(yàn)使變得舒適的用新材料和相關(guān)的過(guò)程的需要來(lái)做產(chǎn)品和系統(tǒng)。當(dāng)人的生命是處在像設(shè)計(jì)航空器這樣的危險(xiǎn)中時(shí)它可能就會(huì)加劇惡化。因此，新材料處理過(guò)程通常是更慢地進(jìn)入市場(chǎng)比預(yù)期的。這些爭(zhēng)端都是工程問(wèn)題要解決的問(wèn)題。材料選擇就是一個(gè)需要算法演譯來(lái)解決的爭(zhēng)議。材料選擇的算法工程需要確切的說(shuō)明，清晰的步聚來(lái)解決問(wèn)題。算法就是一個(gè)用來(lái)解決具體問(wèn)題的比較完善的定義。計(jì)算機(jī)程序是在算法形成之后來(lái)清晰地羅列出這程序要解決的問(wèn)題。例如，你可以寫(xiě)一個(gè)簡(jiǎn)單的算法來(lái)計(jì)算一根輕桿要支撐一個(gè)來(lái)自于輕固定設(shè)備的推力所需的強(qiáng)度。要為內(nèi)燃機(jī)選擇一個(gè)活塞連桿就需要更多更復(fù)雜的算法。第一個(gè)問(wèn)題就是要選擇

42、合適的大小 /強(qiáng)度來(lái)?yè)纹疬@輕設(shè)備，和大多數(shù)材料都會(huì)需要的只要它有足夠的強(qiáng)度和使用起來(lái)較好。另外一方面，連桿將經(jīng)受很多種的機(jī)械應(yīng)力，從壓力到拉伸到扭轉(zhuǎn)到重力級(jí)別。設(shè)計(jì)師將怎樣用可獲得的材料來(lái)匹配零部件？工具選擇為了幫助材料選擇算法的創(chuàng)造，數(shù)據(jù)單元必須是可用的對(duì)于 回答材料適用性這一塊。一個(gè)材料數(shù)據(jù)庫(kù)需要表來(lái)羅列材料的特性，比如拉伸強(qiáng)度，硬度，抗腐蝕性和耐熱性。成千上萬(wàn)種參考書(shū)都是可以得到這樣的數(shù)據(jù)的。這些數(shù)據(jù)的大多數(shù)都已經(jīng)是電腦化了以便于更容易來(lái)訪問(wèn)。某些算法技能幫助了設(shè)計(jì)師來(lái)選擇材料。材料的特性雜質(zhì)能夠提供當(dāng)前的數(shù)據(jù)和所需的材料的使用標(biāo)準(zhǔn)：1強(qiáng)度（拉伸，壓縮，彎曲，剪切和扭轉(zhuǎn)）2耐溫升3抗疲勞

43、性（重復(fù)地裝載和卸載）4剛度（抗沖擊）5耐磨性（硬度）6抗腐蝕性這個(gè)出版物提供這個(gè)執(zhí)行標(biāo)準(zhǔn)為金屬，聚合物和陶瓷，并更新新材料像想到此纖維，鋅鋁合金和更優(yōu)秀的合金。各個(gè)時(shí)期都會(huì)有一年一次的材料選擇器來(lái)提供總一長(zhǎng)串材料特性信息列表。這么多表，含蓋了典型的材料，提供了總的數(shù)據(jù)在材料的特性方面的簡(jiǎn)單比較。選擇具體的材料需要許多詳細(xì)的說(shuō)明書(shū)。來(lái)自于手冊(cè)的數(shù)據(jù)庫(kù)將提供更詳細(xì)的數(shù)據(jù)，但最后的選擇通常需要材料生產(chǎn)商為他們自己的產(chǎn)品生產(chǎn)線提供自己的特性數(shù)據(jù)庫(kù)。當(dāng)數(shù)據(jù)庫(kù)是必須的在最初的材料選擇上，那將會(huì)有其它因素使材料選擇更復(fù)雜。材料系統(tǒng)材料幾乎是獨(dú)立存在的而不與其它材料相互聯(lián)系。而且，一個(gè)材料的選擇與另一個(gè)相互補(bǔ)充。在這成功的材料中，當(dāng)它的獨(dú)特性能促進(jìn)這系統(tǒng)的一部分特性時(shí)它將與其它部件相容合。這藝術(shù)品就是一個(gè)很好的例子。這罩殼可能是結(jié)實(shí)的丙烯腈-丁二烯-苯乙烯塑料，即可以用來(lái)封裝芯片以提供內(nèi)存和完好的傳輸性能。銅、鉛和電路板結(jié)合在一起?？赡苡幸粋€(gè)電池和陶瓷光束真空管來(lái)顯示這電池是低的。酸在電池內(nèi)必須是獨(dú)立地以防止腐蝕，和銅和鉛必須