機(jī)械專英第三課翻譯

1、lesson 3 selecting materialswe are surrounded by materials and we rarely think about how these materials are selected我們被材料包圍著，我們很少考慮這些材料是如何選定的why was your desk made of solid wood, plywood, or plastic-laminated particleboard?為什么你的桌子是實(shí)木、膠合板、或塑料層壓刨花板制造的？why have so many plastics replaced steel and zinc

2、 in automobiles?在汽車?yán)餅槭裁从羞@么多的塑料代替了鋼和鋅？what is the controversy about using foamed polystyrene plastic to package fast food?有關(guān)使用發(fā)泡聚苯乙烯塑料包快餐的爭議是什么？while you might take for granted the materials that make up your products, you can be sure that the designers did not.雖然你可能會(huì)把制造您的產(chǎn)品的材料認(rèn)為是理所當(dāng)然，但是可以確保的是設(shè)計(jì)師卻沒有。

3、people who design homes, cars, aircraft, clothing, furniture, and other products or systems devote a lot of attention to the selection of the materials they use.房子、汽車、飛機(jī)、服裝、家具、其它產(chǎn)品或系統(tǒng)的設(shè)計(jì)者們投入了許多注意力在他所使用的材料 的選擇上。material selection might make or break a company.材料的選擇可能成就或也可能打破一家公司。but how do the design

4、ers make that selection to arrive at the best material?但設(shè)計(jì)者如何讓該到達(dá)的材料的最佳選擇呢？what selection criteria are most important?什么選擇標(biāo)準(zhǔn)是最重要的？the ideal material （理想的材料）1endless and readily available source of supply無止境、隨時(shí)可獲得的供應(yīng)來源2. cheap to refine and produce 捉取和生產(chǎn)廉價(jià)3 energy efficient 能源效率4. strong, stiff, an d

5、imensionally stable at all temperatures 強(qiáng)度，剛度、尺寸的穩(wěn)定性在所有溫度5. lightweight 輕量6 corrosion resistant 耐腐蝕7. no harmful effects on the environment or people 對環(huán)境或人們無害8. biodegradable可生物降解9. numerous secondary uses 眾多的輔助用途obstacles to changeswitching from traditional materials such as steel and concrete to n

6、ewer materials such as plastic-based composites seems a simple, straightforward approach for the contemporary designer.從鋼鐵和混凝土等傳統(tǒng)材料切換到較新的材料，如塑料復(fù)合材料的對當(dāng)代設(shè)計(jì)者是似乎簡單、直接的方法。the newer materials are often superior, but sometimes there are complications較新的材料往往性能更優(yōu)越，但有時(shí)有并發(fā)癥。often, lack of experience with new m

7、aterials causes hesitation by designers通常情況下，新材料與經(jīng)驗(yàn)不足導(dǎo)致rti設(shè)計(jì)師設(shè)計(jì)的猶豫。departures from tried-and-true materials may be costly.、偏離有經(jīng)驗(yàn)的材料可能代價(jià)高昂。it requires time before both designers and fabricators gain sufficient experienceto make products or systems.它需耍設(shè)計(jì)者和加工者獲得使產(chǎn)品或系統(tǒng)成為舒適與新材料及相關(guān)的流程所需的足夠經(jīng)驗(yàn)。this problem

8、is exacerbated when human life might be in jeopardy, such aswhen designing for aircraft此問題加劇時(shí)人類的生活可能陷入困境，如設(shè)計(jì)的飛機(jī)時(shí)。consequently, new materials and processes are usually slower to enter themarketplace than might be expected因此，新的材料和工藝是進(jìn)入市場上通常比預(yù)期慢these issues are all a part of engineering problem solving

9、.這些問題是工程問題需要解決的一部分materials selection is a problem-solving issue that requires an algorithm for its solutio n材料選擇是為其解決方案找到-種算法的問題algorithm for materials selection 材料選擇算法engineering requires clearly stated, unambiguous steps for problem solving.工程 需耍解決問題的清晰、明確的步驟。algorithms are well-defined methods f

10、or solving specific problems.算法是明確定義 的方法，解決具體問題。computer programs are written after an algorithm has been developed to lie out clearly the steps that the program is to solve.后種算法已經(jīng)發(fā)展到躺著明確的程序是解決 的步驟編寫計(jì)算機(jī)程序。for example, you could write a simple algorithm to calculate the strength required of a light p

11、ole to withstand the pushing forces (compression) from a light fixture例如，您可以編寫一個(gè)簡單的算法來計(jì)算所需的一根路燈桿承受推力(壓縮)從輕的夾具的強(qiáng)度。a much more complex algorithm would be required to select a piston connecting rod for an internal-combustion engine.復(fù)雜得多的算法，將要求選擇的內(nèi)燃機(jī)活塞連桿。the first problem requires only the selection of

12、a material of suitable size/strength to hold up the light fixture, and almost any material suffice as long as it was sufficiently strong and pleasing to the user.第一個(gè)問題需要只實(shí)力支撐燈具，合 適大小的一種材料的選擇和兒乎任何材料夠了，只要它是足夠有力和令人愉快，給用戶。on the other hand, a connecting rod will undergo many types of mechanical stress,

13、ranging from compressive to tensile to torsional to gravity forces, in addition to thermal stress from the combustion chamber.另一方面，連接桿會(huì)經(jīng)過許多 類型的機(jī)械應(yīng)力，從壓縮到拉伸到扭重力的力量，從燃燒室內(nèi)的熱應(yīng)力。how does the designer match component requirements with available materials.selection tools設(shè)計(jì)器與可用的材料與組件要求冇什么匹配。to aid in the cre

14、ation of materials selection algorithms, databases must be available to answer questions on material suitability.為了幫助材料選擇算法的創(chuàng)作中，數(shù) 據(jù)庫必須可用回答有關(guān)材料適合的問題。a material database involves tables listing properties of material, such as tensile strength, hardness, corrosion resistance, and the ability to withsta

15、nd heat.材料數(shù) 據(jù)庫涉及表格列出了屈性的材料，如拉伸強(qiáng)度、硬度、耐腐蝕性和熱的承受能力。thousands of reference books are available with such data提供此類數(shù)據(jù)與成千上力的 參考書籍。much of these data are computerized to allow easier access.許多這些數(shù)據(jù)計(jì)算機(jī)化以 允許更容易訪問。certain graphical techniques aid the designer in materials selection某些圖形技術(shù)援 助在材料選擇中的設(shè)計(jì)器。properties

16、 of materials 材料的性能periodicals can provide current data and performance criteria that involve structural materials:當(dāng)前數(shù)據(jù)和涉及結(jié)構(gòu)材料的性能標(biāo)準(zhǔn)，可提供期刊：1 strenghth (tensile, compressive, flexural, shear, and torsional)關(guān)于我們(拉伸、壓 縮、彎曲、剪切、扭)2 resistance to elevated temperatures 耐高溫3. fatigue resistance(repeated load

17、ing and unloading)抗疲勞(重復(fù)裝載和卸載4. toughness(resistance to impact)韌性(抗沖擊性能)5 wear resistance(hardness)耐磨性(硬度)6 corrosion resistance 耐腐蝕such publications present values for the performance criteria (properties) for metals, polymers, and ceramics, with updates on newer materials such as aramid fibers, zi

18、nc aluminum alloys, and super alloys.這類岀版物使用較新的材料，如芳綸纖維、鋅鋁合金材料和超級合金上更新現(xiàn)有的金屬、聚合物和陶瓷 的標(biāo)準(zhǔn)(屬性)的值。various periodicals have annual materials selectors that provide general information on properties for a long list of materials.各類期刊有一長串的材料屬性提供一般信息的年度材料選擇清單。the many tables, covering representative materials

19、, provide general data on properties for a simple comparison許多表格，覆蓋代表的材料，提供一般數(shù)據(jù)屬性作簡單的比較。selection of specific materials requires many more detailed specifications.具體材料的選擇，需要很多更詳細(xì)的規(guī)格。general databases from hand books will provide much detail, but the flnalselection often requires that material manufa

20、ctures supply their own properties database for their product lines手冊會(huì)提供很多詳細(xì)信息，但最終的選擇往往需要為他們的產(chǎn)品線材料制品提供他們口己的屬性數(shù)據(jù)庫。while databases are imperative in the initial selection steps, there are other factors that complicate materials selection雖然數(shù)據(jù)庫都必須在初始選擇的步驟中，但也有其它復(fù)雜材料選擇的因素。materials systems 材料系統(tǒng)materials

21、rarely exist in isolation without interacting with other materials.材料很少存在分離而不與其它材料進(jìn)行交互。rather, a combination of materials is selected to complement one another.相反，選擇的材料組合相互補(bǔ)充。in a successful materials system, each component is compatible with the others while contributing its distinctive properties

22、to the overall characteristics of the system of which it is a part在成功的材料系統(tǒng)屮，每個(gè)組件同時(shí)促進(jìn)了其獨(dú)特的屬性，其中相當(dāng)一部分的總體特點(diǎn)是系統(tǒng)的與其他兼 容的。a state-of-the-art telephone is a good example先進(jìn)的電話是一個(gè)好例子。the casing might be a tough abs plastic, which houses a microchip (a solid-state ceramic device) that provides memory and soun

23、d-transmission capabilities.石油套管可能強(qiáng)硬的abs塑料，提供了內(nèi)存和聲音傳輸功能的芯片(固態(tài)陶瓷設(shè)備)的房子copper leads join the circuitry together.銅導(dǎo)線將電路連接起來。there might be a battery and a ceramic light-emitting diode to show when the battery is low.電池較低時(shí)可能有一個(gè)電池和陶瓷發(fā)光二極管顯示。the acid in the battery must be isolated to prevent corrosion, a

24、nd the copper leads must be insulated so that they do not short out.電池中的酸必須隔離，防止腐蝕，并必須絕緣銅的線索，以便他們不短路。each component is made of materials that meet the demands of the physical and chemical environment normally encountered when using the system每個(gè)組件rti滿足系統(tǒng)的物理和化學(xué)壞境要求的材料組成。additional selection criteria 更

25、多選擇條件existing speciheations have a lot of influence on the choice of material現(xiàn)有規(guī)范有很多對材料的選擇的影響。these specifications or “standards” are used when redesigning an improved model of the product.重新設(shè)計(jì)產(chǎn)品的一種改進(jìn)的模型時(shí)，將使用這些規(guī)格或”標(biāo)準(zhǔn)”。when the materials-selection algorithm results in selection of a new material, it

26、might not be covered by current speciflcations from standardization agencies 當(dāng) 材料選擇算法產(chǎn)生一種新材料的選擇時(shí)，它不可能涵蓋的電流規(guī)格標(biāo)準(zhǔn)化機(jī)構(gòu)。the conditions of safety must be met by those involved in the manufacture or use of goods and services安全的條件必須符合的那些參與制造或使用的商品和服務(wù)。it might take considerable time for these agencies to alte

27、r their specifications to include the new material or they might not approve its use.可能需耍相當(dāng)長的時(shí)間來改變他們以包括新材料的規(guī)范這些機(jī)構(gòu)或他們可能不會(huì)批準(zhǔn)其使用。availability is another concern of the designer.可用性是設(shè)計(jì)者的另一個(gè)關(guān)注的問題。will the material be easily available in the quantities and sizes required by the production demands?材料在容易獲得所

28、需的數(shù)量和大小嗎？in addition, will it be available in many varieties of standard shapes, such as round, oval, and square tubing此外，在多種的形狀標(biāo)準(zhǔn)如圓、橢圓和平方油管屮可用嗎？in the past, designers were limited to existing materials such as metal alloys, woods, or concrete在過去，設(shè)計(jì)師們限于現(xiàn)有的材料，如金屬合金、樹林或混凝土。now , it is possible to star

29、t from scratch at the synthesis stage to have materials engineers design a materials system to provide properties to meet the expected needs現(xiàn)在，很可能有材料工程師設(shè)計(jì)材料系統(tǒng)提供屬性，以滿足預(yù)期的需求合成階段從零開始。processibility, the ease with which raw materials can be transformed into a flnished product, is of paramount concern絕緣性

30、、易用的原料都能變成成品，是極為關(guān)注的問題。much of the current focus is on low-energy processing低能量處理是很多的當(dāng)前焦點(diǎn)。companies may have difficulty processing the new material on existing equipment.公司可能難以處理現(xiàn)有的設(shè)備上的新材料can they afford to invest in new equipment?他們可以承受投資新設(shè)備嗎？today, the reverse question is usually asked: can we affo

31、rd not to use the new material and process?今天，反通常問這樣的問題：我們能不使用新材料和過程嗎？if we do not, the competition might make the change and run us out of business with their superior product.如果我們不這樣做，競爭可能進(jìn)行更改，其優(yōu)越的產(chǎn)品可能使我們被逐出局。many new technologies are now available.現(xiàn)在很多的新技術(shù)是可用的quality and performance are two aspec

32、ts that achieve consumer satisfaction質(zhì)量和性能是使消費(fèi)者滿意的兩個(gè)方血。the high cost of most durable goods and the competition for customer acceptance has resulted in extended warranties最耐用物品的高成本和接受客戶的競爭延長了產(chǎn)品的保修期。materials selection must ensure that parts will not rust, break under repeated stress, or fail to perfo

33、rm in any other way for the predicted service life of the product.材料選擇必須確保零件將不生銹、反復(fù)脅迫、破壞或任何其他方式不會(huì)降低產(chǎn)品的預(yù)期壽命。consumer acceptance includes many factors beyond excellent quality and high performance; there are also societal aspects消費(fèi)者接受包括許多因素除了超越卓越的品質(zhì)和高性能，也有社會(huì)方面的問題。society as a whole as well as governme

34、ntal agency is requiring a closer look at manufactured products作為一個(gè)整體，以及政府機(jī)構(gòu)的社會(huì)需要仔細(xì)看看制造的產(chǎn)品。any product has to be considered in terms of its total life cycle.任何產(chǎn)品，必須從其全生命周期的角度考慮。what are the results of the processing methods?處理方法的結(jié)果是什么？are polluting gases being released into the environment, or are t

35、oxic metals and chemicals being flushed into our rivers and streams?正在污染氣體被釋放到環(huán)境中，或者是有毒金屬和化學(xué)品沖入河流及溪澗嗎？during use, does the product safeguard our health?該產(chǎn)品在使用屮維護(hù)我們的健康嗎？at the end of the produces useful life, how can it be disposed of safely?在該產(chǎn)品的使用壽命結(jié)朿時(shí)，如何可以安全處置它？municipal solid waste is hidden prod

36、uct cost that we pay in the form of higher taxes and a poorer quality of life?都市固體廢物是我們以形式更高的稅收和貧窮的生活質(zhì)量我們付出的隱藏的產(chǎn)品成本嗎？fast-food restaurant chains moved away from polystyrene packages because the public felt these plastic containers were more harmful to the environment than paper packaging連鎖快餐餐館不用聚苯乙烯

37、包裝帶，因?yàn)槭忻裾J(rèn)為這些塑料容器都對環(huán)境比紙包裝更有害。soft-drink manufactures are moving toward reusable plastic bottles.軟性飲料制造業(yè)正在走向可重復(fù)使用的塑料瓶。design for disassembly has become a theme in much of product design by major corporations 面向拆卸設(shè)計(jì)已成為很多大公司的產(chǎn)品設(shè)計(jì)的一個(gè)主題。europe, which has a higher degree of ecological concern, has led the

38、way.擁有較高程度的生態(tài)關(guān)懷的歐洲走在世界前列主導(dǎo)這種設(shè)計(jì)。with the desire to facilitate recycling, manufacturers of small appliances and durable goods are establishing procedures to ensure that products can be broken into components for easy sorting prior to recycling隨著人們希望有利于廢品的回收，一些小型電器和耐用品廠家開始建立一種方法來確保他們生產(chǎn)的產(chǎn)品能 夠被分解成很小的部件來便

39、于回收利用。among the procedures are reducing the variety of plastics, adding labels to plastics for easy identification of plastic type, and eliminating screws and adhesives so that parts will disassemble easily.來便于各部分零件的拆卸。one of the latest software programs is designed specifically to make products eas

40、ier to fix.又一個(gè)最新的軟件是專門用來設(shè)計(jì)如何使產(chǎn)品更容易拆裝的known as design for service, this program takes its place alongside previous software programs called design for assembly and design for manufacturability.就像我們知道的面向維修的設(shè)計(jì)，這個(gè)程序取代了別的先前的面向裝備配設(shè)計(jì)和面向可制造性的設(shè)計(jì) 這兩種程序。this new program helps product designers consider repair

41、issues early in the design stage這種新型的程序幫助了產(chǎn)品設(shè)計(jì)者在設(shè)計(jì)階段就開始考慮維修的問題。objectives of the program include making repairs less costly and extending the functioning life of products這個(gè)程序的作用包括 了使產(chǎn)品獲得更加低廉的維修費(fèi)用和更長時(shí)間的使用壽命。environmental issues such as recycling are directly addressed by this new computer software, w

42、hich may have customers fixing products rather than tossing them out.關(guān)于環(huán)境因素，就像循環(huán)利用，這個(gè)軟件能夠直接幫你解決，比如可能使顧客固定產(chǎn)品而不是抖動(dòng)in addition, this software augments product for whatever reason另外，這個(gè)軟件無論如何都增漲了產(chǎn)品。more often than not, cost is the primary selecting criterion that will determine the final choice of material.材料成本的主要選擇標(biāo)準(zhǔn)通常將決定材料的最后決世。in other words, if several materials have the specified physical, mechnical, and ch