Specimen edge effects on bending fatigue of carburized steel
食品中铁、锰元素检测方法探讨
食品科技食品中铁、锰元素检测方法探讨史秋梅（临沂市河东区疾病预防控制中心，山东临沂 276034）摘 要：铁元素和锰元素是人体必需的微量元素，在多种生理机能中发挥着关键作用。
然而，过度摄入可能会对人体产生不利的影响，因此食品中铁元素和锰元素的分析检测显得尤为重要。
本文介绍了食品中铁元素和锰元素分析的必要性，并针对食品中铁、锰元素的检测分析方法，如原子吸收光谱法、高效液相色谱法、电感耦合等离子体原子发射光谱法、电感耦合等离子体质谱法以及X射线荧光光谱法等进行了概述，以期保障食品中铁、锰元素含量的安全性和合规性，从而更好地服务于食品分析领域。
关键词：铁元素；锰元素；分析方法；应用；食品安全Exploration of Detection Methods for Iron and ManganeseElements in FoodSHI Qiumei(Hedong District Center for Disease Control and Prevention, Linyi 276034, China) Abstract: Iron and manganese are essential trace elements for the human body and play crucial roles in various physiological functions. However, excessive intake may have adverse effects on the human body, so the analysis and detection of iron and manganese elements in food is particularly important. This article introduces the necessity of analyzing iron and manganese elements in food, and provides an overview of detection and analysis methods for iron and manganese elements in food, such as atomic absorption spectroscopy, high-performance liquid chromatography, ionization coupled plasma atomic emission spectroscopy, ionization coupled plasma mass spectrometry, and X-ray fluorescence spectroscopy, in order to ensure the safety and compliance of iron and manganese content in food, so as to better serve the field of food analysis.Keywords: iron; manganese; analytical methods; applications; food safety铁和锰是食品中的两种微量元素，对维持身体健康具有重要意义[1]。
专业英语
Definition of polymers A simple understanding of polymers can be gained by imaging them to be like a chain or, perhaps, a string of pearls, where the individual pearl represent small molecules that are chemically bonded together. Therefore, a polymer is a molecule made up of smaller molecules that are joined together by chemical bonds. The word polymer means „many parts or units.‟ The parts or units are the small molecules that combine. The result of the combination is, of course, a chainlike molecule (polymer). Usually the polymer chains are long, often consisting of hundreds of units, but polymers consisting of only a few units linked together are also known and can be commercially valuable.
Figure 1.1 Diagram illustrating the definition of plastics.
As Figure 1.1 shows, all materials can be classified as gases, simple liquids, or solids, with the understanding that most materials can be converted from one state to another through heating or cooling. If only materials that are structural solids at normal temperatures are examined, three major types of materials are encountered: metals, polymers, and ceramics. The polymer materials can be further divided into synthetic polymers and natural polymers. Most synthetic polymers are those that do not occur naturally and are represented by materials such as nylon, polyethylene, and polyester. Some synthetic polymers could be manufactured copies of naturally occurring materials (such as
到9月9日
到9月9日，社保基金正式进入股市整整3个月，按照有关规定，社保基金必须通过基金管理公司在三个月内完成建仓，并且其持仓市值要达到投资组合总市值80%的水平。
与此前大受追捧的QFII概念相比，社保基金及其所持有的股票显然低调得多，但是在西南证券分析师田磊看来，至少就目前来看，社保基金无论是在资金规模，还是在持股数量上明显都强于境外投资者，其投资理念和行为更可能给市场带来影响。
基金操作的社保基金的选股思路并不侧重某个行业，而更看重企业本身的发展和成长性，并且现阶段的企业经营业绩和走势也不是基金重点考虑的方面。
目前入市的社保基金都是委托南方、博时、华夏、鹏华、长盛、嘉实6家基金管理公司管理。
社保基金大致是被分为14个组合由以上6家管理公司分别管理，每个组合都有一个三位数的代码，第一位代表投资方向，其中“1”指股票投资、“2”指债券投资；第三位数字则代表基金公司名称，其中“1”为南方、“2”为博时、“3”为华夏、“4”为鹏华、“5”为长盛、“6”为嘉实；另有107、108组合主要运作社保基金此前一直持有的中石化股票，分别由博时与华夏基金公司管理。
在许多社保基金介入的股票中经常可以看到开放式基金的身影，例如在被社保基金大量持有的安阳钢铁(600569)的前10大股东中，其第2、6、7、8、9大股东均为开放式基金，而社保基金则以持股500多万股位列第3大股东。
类似的情况也出现在社保基金103组合所持有的华菱管线(000932)上，其第二大股东即为鹏华行业成长证券投资基金，社保基金则以200多万股的持仓量位列第7大股东，此外，在其前10大股东中还有5家是封闭式基金。
对此，某基金公司人士解释说，在获得社保基金管理人资格后，6家基金公司成立了专门的机构理财部门负责社保基金的投资管理，但是其研究、交易系统等则与公募基金共用一个平台，因此社保基金和开放式基金在选股时才会如此一致。
针对“社保概念股”的走势，国盛证券的分析师王剑认为，虽然社保基金此次委托入市资金超过百亿元，但大部分投向是债券，而且由于社保基金的特殊地位，因此基金管理公司对社保基金的操纵策略应该是以“集中持股，稳定股价”为主，不大可能博取太高的收益。
应用地球化学元素丰度数据手册-原版
应用地球化学元素丰度数据手册迟清华鄢明才编著地质出版社·北京·1内容提要本书汇编了国内外不同研究者提出的火成岩、沉积岩、变质岩、土壤、水系沉积物、泛滥平原沉积物、浅海沉积物和大陆地壳的化学组成与元素丰度，同时列出了勘查地球化学和环境地球化学研究中常用的中国主要地球化学标准物质的标准值，所提供内容均为地球化学工作者所必须了解的各种重要地质介质的地球化学基础数据。
本书供从事地球化学、岩石学、勘查地球化学、生态环境与农业地球化学、地质样品分析测试、矿产勘查、基础地质等领域的研究者阅读，也可供地球科学其它领域的研究者使用。
图书在版编目（CIP）数据应用地球化学元素丰度数据手册/迟清华，鄢明才编著. －北京：地质出版社，2007.12ISBN 978－7－116－05536－0Ⅰ. 应… Ⅱ. ①迟…②鄢…Ⅲ. 地球化学丰度－化学元素－数据－手册Ⅳ. P595－62中国版本图书馆CIP数据核字（2007）第185917号责任编辑：王永奉陈军中责任校对：李玫出版发行：地质出版社社址邮编：北京市海淀区学院路31号，100083电话：（010）82324508（邮购部）网址：电子邮箱：zbs@传真：（010）82310759印刷：北京地大彩印厂开本：889mm×1194mm 1/16印张：10.25字数：260千字印数：1－3000册版次：2007年12月北京第1版•第1次印刷定价：28.00元书号：ISBN 978－7－116－05536－0（如对本书有建议或意见，敬请致电本社；如本社有印装问题，本社负责调换）2关于应用地球化学元素丰度数据手册（代序）地球化学元素丰度数据，即地壳五个圈内多种元素在各种介质、各种尺度内含量的统计数据。
它是应用地球化学研究解决资源与环境问题上重要的资料。
将这些数据资料汇编在一起将使研究人员节省不少查找文献的劳动与时间。
这本小册子就是按照这样的想法编汇的。
最新版本工程应用英语
工程应用英语课程一．单选题：1. Computers are(B. useless)unless they are given clear and accurate instructions and information.2. Active (B. Recruiting) for engineers often begins before the student’s last year in the university.3. For the student who is preparing to become a (C. Civilengineer), these specialized courses may deal with such subjects as geodetic surveying, soil mechanics.4. The civil engineer may work in research, design, construction,(B. Supervision), maintenance, or even in sales.5. Civil engineers work on many different kinds of (C. Structures).6. In designing buildings, civil engineers often work as (B. Consultants) to architectural or construction firms.7. Dams, bridges and other large projects ordinarily employ several engineers whose work is coordinated by a (D. Systems) engineer who is in charge of the entire project.8. Construction is a(B. Complicated) process on almost all engineering projects.9. In compression, the material is (C. Pushed) together.10. When a saw cuts easily through a piece of wood, the wood is (A. in tension).11. We defined (D. Shear) as the tendency of a material to fracture along the lines of stress.12. The principal construction materials of earlier times were wood and (C. masonry brick),stone, or tile, and similar materials.13. Modern cement is a mixture of(B. limestone and clay).14. Concrete is very (D. Versatile) 15. Steel has great tensile strength whileconcrete has great compressive strength,thus, the two substances (C. Complement)each other.16. One system that helps (A. Cut)concrete weight to some extent usespolymers.17. The retention money serves to insure(D. the employer)against any defects thatmay arise in the work.18. The civil engineering work must becompleted to the satisfaction of theemployer, or his(D. Representative)19. For moderate and longer hauls,self-loading scrapers pulled byrubber-tired hauling units and push-loadedby tractors offer(B. Lower) cost.20. Highway maintenance activities canbe grouped and classified according (D.to)the purpose of the treatment.21. Engineering is a profession, whichmeans that an engineer must have aspecialized(D．university )education.22. In most cases, the tender maybe(B．Withdrawn)at any time until it hasbeen accepted.23. Current trend is to require students totake courses in the(C.social)science andthe language arts.24. The law relating to contracts imposeson each party to a contract (D. a legalobligation) to perform.25. Indeed, the civil engineer’s choiceis(C. large)and varied.26. Roadbeds (B. underlie) highwaypavement structures and the ballast andtrack on which trains move.27. Construction can be very (A.dangerous).28. Where material is moved less thanabout 60m or steeply downhill, driftingwith a track or wheel type bulldozer is (A.cheapest)29. Thrust is the pressure exerted by eachpart of a structure on (A. its other part)30. The weight of all the people, cars,furniture, and machines and so on that thestructure will support when it is in use is(B. live load)31. In tension, the material is(B. pulledapart)32. In fills constructed by end dumping orby placing in thick layers, material,density, and moisture content could (C.vary) greatly from one spot to another.33. Both (A. steel and cement), the twomost important construction materials ofmodern times, were introduced in thenineteenth century.34. The total station is used to measureangles in both vertical and horizontalplanes, and the level to measure (C.elevation difference)35. The (B. defective )vehicle is a creatorof accidents.36. Prestressed concrete is an (B.improved )form of reinforcement.37.A simple contract consists of anagreement entered into by( D. two ormore parties)38.(B. V olume) change would result indifferential settlement or swell betweenadjacent areas.39. There are two basic procedures forcontrolling the embankment density:‘manner and method’ and ‘(A. result )’.40.A main source of accidents, theproblem of(C. drunken)driving is the mostserious of all.41. Computer programming is nowincluded in almost all engineering(B.curricula).42. The relationship between engineeringand society is getting( C. Closer)43. Types of contracts are virtually classified by their(D. payment)system: (1) price-based and (2) cost-based.44. Computers can’t solve complicated problems unless they are given( D. a good program)45. In recent years, rippers have been used successfully to( C. break up)loose or fractured rock.46. Civil engineering projects are almost always (A. distinctive)47. Usually there are (C. no)easy answers on equipment selection.48. (A. Vertical)force acts up and down.49. Layered construction also produced greater uniformity in the material( D. itself)and in its density and moisture content.50. The actual cost of any single highway traffic accident is extremely( C. difficult )to determine.51. Basically, causes of automobile accidents can be categorized(D. into)four major groups.52. Electronic distance measuring (EDM) not only can measure the distance between objects but also determine( A. the direction)53.(A. Two of )the recent improvement in visibility are wraparound windshields and narrowed roof support pillars.54. There is a great deal that the actual highway designer can( C. do to)prevent accident.55. To avoid the driving after drinking, one of the methods is( B. breath test ). 56. It is suitable for remote sensing technique to be used for highway location in(C. mountainous country without forest).57. The information on the aerial photographs can be converted into mapswith the help of stereoscopes which isable to see objects in(C. three dimensions)58. The normal steel does not exert anyforce of its own on the member,( B.contrary)to the action of prestressingsteel.59. The extensive use of prestressedstructures has been due in ( A. no )smallmeasures to the advances in thetechnology.60.The employer selects the contractor forthe project by( D. Bidding).61. Many different( A. corporations ) andgovernment agencies have competed forthe services of engineers in recent years.62. Civil engineers may prefer to workwith one of the government agenciesthat( B. deals )with water resources.63. It is normal practice for( B. a)engineerto specialize in just one kind.64. Construction involves the work andutilizing the equipment and the materialsso that costs are kept as( C. low )aspossible.65. For example, (B. dams)are often builtin wild river valleys or gorges.66. Electrical and mechanical engineerswork on the(A. design )of the powerhouseand its equipment.67. In Rome, most of the people livedin(B. insulse ), great tenement blocks thatwere often ten stories high.68. The prospective civil engineer shouldbe aware of the physical( A.Conditions)that will be made on him orher.69. Much of the work of civil engineeringis carried on( C. outdoors)70. In addition, the building ofskyscrapers, bridges and tunnels must alsoprogress under all kinds of(C.weather)conditions.71. The Romans also used a naturalcement called pozzolana, made from (B.volcanic ash), that became as hard asstone under water.72. Different proportions of theingredients produce concrete with( A.different )strength and weight.73. (A. Prestressed) concrete has made itpossible to develop buildings with unusualshapes.74. The modern engineer must alsounderstand the (C. different)stresses towhich the materials in a structure aresubject.75. Today, scientific data permit theengineer to make careful calculations( D.in advance)76. The force which the live load will beexerted on the structure is( C. Impact)77. When a saw begins to bind, the woodis( A. in compression because)the fibersin it are being pushed together.78. ( D. Steel )rods are bent into theshapes to give them the necessary degreeof tensile strength.79. Many great buildings built in earlierages are massive structures with( B. thickstone walls)80. We all enter into contracts almostevery day for the supply f goods,(Btransportation)etc.81. Some contracts must be made in aparticular(D. form)to be enforceable.82. Once a person has signed a documenthe is assumed to have(B. approved)itscontents.83. By setting down the terms of acontract in writing one secures avoiding( A. disputes)84. In an entire contract, where( D. theemployer)agrees to pay a certain sum inreturn for civil engineering work..85. (B. The contractor ) is not entitled to any payment if he abandons the work prior to completion.86. The contractor is not entitled to receive payment in (A. full )until the work is satisfactorily completed.87. A tender is normally required to be a definite( C. offer)88. Generally, civil engineering contracts provide for the issue of (B. interim certificates)at various stages of the works.89. It does not give the employer the right to demand an(A. unusually)high standard of quality throughout the works.90. The employer does not usually bind himself to accept the lowest or indeed any tender and this is often stated in the(C. advertisement )91. A contract has been defined as an agreement which directly creates and contemplates( C. an obligation)92. When we enter into contracts we are willing to(C. pay )for the service we receive.93. If there is no written agreement and( C.a dispute )arises in respect of the contract.94. The rubber-tired tractor units have difficulty in operating on( D. wet), slippery roadbeds.95. There are( A. Many)variables in earthmoving.96. The term(D. Embankment)describes the fill added above the low points along the roadway to raise the level to the bottom of the pavement structure.97. Material for( B. embankment)commonly comes from roadway cuts or designated borrow areas.98.(C. Field) control is largely a matter of conducting the specified procedure.99. Modern practice requires that embankment construction be( A.carefully )executed and controlled.100. Construction of pavement over highfills often was( B. deferred )for a year ormore after completion of the fill to allowthe settlement to occur.101. Nearly( B. all)vegetable mattershould be removed from the originalground and fill material.102. A track or wheel type bulldozer is( D.not suitable)to earthmoving ofconsiderably long hauls.103. Loose rock is handled by( A.tractor-scraper)units as is done with‘common’ excavation.104. The highway can require mentaland( A. physical) response.105. The needs generated by the greatincrease( D. in)vehicle numbers andkilometers of road have given rise tomajor research programs in trafficplanning.106. Terminology concerned( B.with)highway preservation variesconsiderably from country to country.107. Highway improvement is also a keyfactor( B. in) preventing accidents.108. The actual degree of safety oneexperiences on a given highway isdetermined by decisions made on ( B.different) levels.109. Public agencies typically dictate themajor constraints within which thesedesign decisions are( A. to be) made.110. Finally, individual motorists makedecisions regarding their own safety ( C.as) they select speed, route for their cars.111. Safe highways are ( C. expensive)and it appears that the driving public doesnot want safe highways.112. People do not want to pay the costsand suffer the restrictions necessary toproduce ( A. safety) in traffic.113. It is often ( A. impossible)todetermine the true condition of a vehicleafter a crash.114. No figures( B. are)available tojustify it.115. For the driver’s vision, in the body ofthe automobile, both side and rearwindows have been greatly( D. enlarged)in area.116. Another improvement in drivervisibility is the introduction of theremote-controlled( B. outside)rearviewmirror.117. The safe performance of the brakesystem( C. under)high temperatures hasbeen ensured.118. Relocation and reduction in theheight of the brake pedal has meant thatthe brake can be applied( A. much)rapidly.119. The use of uniform traffic controldevices will reduce driver reactiontime( A. as well as) confusion.120. Removal, relocation and redesign offixed obstructions, can provide a clear( C.recovery) area for vehicles out of control.121. Vehicular safety design usuallycenters( B. upon) protecting the driver andhis passengers.122. The highway construction may alsocause( D. adverse)impacts on thesurroundings.123. The designed highway alignmentmust meet the technical( B. standard)ofthe highway engineering.124.( A. Hot rolled asphalt)is a gapgraded material with less coarseaggregate.125. In this case, layer thickness, moisturecontrol, and the number of passes by aroller of specified type and weight are( A.predetermined).126.( B. Ground survey)is the conventional location technique for highway.127. A( B. total station)is only used for measuring the vertical heights of objects. 128. If Party A commissions Party B to execute the construction work, then Party B is referred to as( B. the contractor). 129. The force-account work should be checked and approved daily by( D. both A and B) .130.( A. Fast speed)is not advantage of highway transportation.二．填空题：131. Engineers often work as( consultants)to architectural or construction firms.132. Young engineers may choose to go into( environmental)or sanitary engineering.133. It is sufficient in order to create a legally( binding), if the parties express their agreement and intention to enter into such a contract.134. One party to the contract is( liable)for breach of contract if he fails to perform his part of the agreement. 135.( Clearing)the site precedes all grading and most other construction operations.136. Loose rock includes materials such as( rotten or weathered)rock, or earth mixed with boulders.137. No attempt was made to control( moisture)content or to secure compaction.138. The( redesign)of windshield wipers, fresh air ventilating systems, had result in greater vehicle safety.139. The safe performance of the brake system has been ensured by the use of( heavy-duty)brake fluid.140. Relocation and reduction in height ofthe brake( pedal)has meant that thedriver’s total reaction time has beenreduced.141. Areas of research connected withcivil engineering include soil mechanicsand ( soil stabilization) techniques.142. Modern cement, called ( Portlandcement), was invented in 1824.143. Material for embankment commonlycomes from roadway cuts or designated( borrow areas).144. Causes of automobile accidents canbe categorized into four major groups: thevehicles, the road, the driver, the( pedestrain) .145. Another improvement in drivervisibility is the introduction of theremote-controlled outside ( rearview)mirror.146. Rock nearly always must be drilledand blasted, then loaded with a front-endloader or ( power shovel)into trucks orother hauling units.147. The three forces that can act on astructure are( vertical force), horizontalforce, and those that act upon it with arotating or turning motion.148. Highway pavements are divided intotwo main categories: ( rigid) and flexible.149. Flexible pavements are furtherdivided into three subgroups: high type,( intermediate), and low type.150. The constructing steps of thetransportation system are to plan, design,build, operate and ( maintain).151. The unit price contract is adapted tohighway engineering, because usually it isnot possible to determine exact quantitiesof some items of work ( before)construction is completed.152. The word ‘contract’is derived fromthe Latin ‘contractum’, meaning( drawn)together.153. As a structural material, theenormous advantage of steel is its ( tensilestrength).154. ( Highway transportation)is thedominant transportation mode inpassenger travel.155. The Portland cement concretecommonly used for rigid pavementsconsists of Portland cement, coarseaggregate, ( fine aggregate), water.156. Rigid highway pavement can bedivided into three general types: plainconcrete pavements, simply reinforcedconcrete and ( continuously reinforcedconcrete)pavements.157. The simplest and generally leastcostly form of interchange is the( diamond).158. If distances are great and time is at apremium, ( air)transportation will beselected.159. Signing for freeways should beplanned concurrently with the ( geometry)design.160. Major drainage structures are usuallylarge bridges and multi-span ( culverts).161. The weight of the structure itself isknown as( dead load).162.( Prestressed) concrete is an improvedform of reinforcement.163. A simple contract consists ofan( agreement)entered into by two ormore parties.164. This sum is known as ‘( retention)money’ and serves to insure the employeragainst any defects that may arise in thework.165. Thus,( On-the-job )training can beacquired to translate theory into practiceto the supervisors.166. Large projects ordinarily employ several engineers whose work is coordinated by a( systems engineer). 167. Traffic loads are transferred by the wearing surface to the underlying supporting materials through the interlocking of aggregates, the frictional effect of( granular materials), and cohesion of the fine materials.168. Excavation is the process of loosening and removing earth or rock and transporting it to a fill or to a( waste deposit).169. When planning a structure, an engineer must take into account four factors: dead load,( live load), impact and safety factor.170. The new design standards require( guard)rails and other structures to lessen a vehicle’s impact.171. People select( air transportation)to carry important goods when time is at a premium.172. The benefit-cost ratio method is used for evaluating the( economical)and environmental feasibility of the alternative routes.173. A unique bridge site or a mountain pass also mat become a primary( control point ).174. The radius of a tangent is( infinite), and that of a curve is finite.ing collector-distributor roads can overcome weaving movement of the( cloverleaf) interchange.三．阅读理解题：Passage OneResearch is one of the most important aspects of scientific and engineering practice. A researcher usually works as a member of a team with other scientistsand engineers. He or she is oftenemployed in a laboratory that is financedby government or industry. Areas ofresearch connected with civil engineeringinclude soil mechanics and soilstabilization techniques, and also thedevelopment and the testing of newstructural materials.176. Research is one of ( B. the mostimportant)aspects of scientific andengineering practice.177. A researcher is often employed( C. ina laboratory).178. A researcher usually works as amember of a team with( C. scientists andengineers).179. Which of the following is true?(A.Civil engineering research doesn’t includeonly soil mechanics and soil stabilization,but also the development of new structuralmaterials)Passage TwoThe current tendency is to develop lightermaterials. Aluminum, for example, weighsmuch less than steel but has many of thesame properties. Aluminum beams havealready been used for bridge constructionand for the framework of a few buildings.Attempts are also being made to produceconcrete with more strength and durability,and with a lighter weight. One system thathelps cut concrete weight to some extentuses polymers, which are long chainlikecompounds used in plastics, as part of themixture.180. The current trend of structuralmaterials is( B. to develop lightermaterials).181. Aluminum weighs( A. much less thansteel).182. Aluminum has( C. many of the sameproperties of steel) .183. Which of the following is true?(B.Aluminum beams can be used for not onlybridge construction but also theframework of a few buildings)Passage ThreeSteel and concrete also complement eachother in another way: they have almost thesame rate of contraction and expansion.They therefore can work together insituations where both compression andtension are factors. Steel rods areembedded in concrete to make reinforcedconcrete in concrete beams or structureswhere tension will develop. Concrete andsteel also form such a strong bonds—theforce that unites them—that the steelcannot slip within the concrete. Stillanother advantage is that steel does notrust in concrete. Acid corrodes steel,whereas concrete has an alkaline chemicalreaction, the opposite of acid.184. Steel and concrete have( C. almostthe same rate of contraction andexpansion).185. Reinforced concrete is( A. steel rodswhich are embedded in concrete beams).186. Which of the following is true?(C.steel does not rust in concrete)187. Concrete has( B. an alkalinechemical reaction, the opposite of acid).Passage FourThe employer or promoter of civilengineering works normally determinesthe conditions of contract, which definethe obligations and performances by someform of competitive tendering and anycontractor who submits a successfultender and subsequently enters into acontract is deemed in law to havevoluntarily accepted the conditions of contract adopted by the promoter.The obligations that a contractor accepts when he submits a tender are determined by the form of the invitation to tender. In most cases the tender may be withdrawn at any time until it has been accepted and may, even then, be withdrawn if the acceptance is stated by the promoter to be ‘subject to formal contract’ as is often the case.188. The conditions of contract are normally determined by( C. the promoter). 189. This conditions define the obligations and performances to which (C. the contractor) will be subject.190. The obligations that( C. the contractor)accepts when he submits a tender are determined by the form of the invitation to the tender.191. In most cases the tender may be withdrawn at any time until( B. it has been accepted) .Passage FiveMaterials are usually described as ‘rock’, ‘loose rock’, or ‘common’, with ‘common’signifying all material not otherwise classified. Rock, sometimes called ‘solid rock’, nearly always must be drilled and blasted, then loaded with a front-end loader or power shovel into trucks or other hauling units. Blasted rock may be moved or drifted for short distances by means of a bulldozer, which is, in effect, a huge tractor-mounted blade. Loose rock often is dug with loaders or shovels without any previous blasting. 192. According to the passage, which material signifying all material not otherwise classified.( B. common)193. Which of the following is NOT true?( B. rock, is sometimes called ‘looserock’)194. According to the passage, which ofthe following is true?( B. loose rock isoften dug without any previous blasting)195. Loose rock often is dug with( B.loaders or shovels)without any previousblasting.Passage SixIn the university, mathematics, physics,and chemistry are heavily emphasizedthroughout the engineering curriculum,but particularly in the first two or threeyears. Mathematics is very important inall branches of engineering, so it is greatlystressed. Today, mathematics includescourses in statistics, which deals withgathering, classifying, and usingnumerical data, or pieces of information.An important aspect of statisticalmathematics is probability, which dealswith what may happen when there aredifferent factors, or variables, that canchange the results of a problem. Beforethe construction of a bridge is undertaken,for example, a statistical study is made ofthe amount of traffic the bridge will beexpected to handle. In the design of thebridge, variables such as water pressureon the foundations, impact, the effects ofdifferent wind forces, and many otherfactors must be considered.196. Mathematics is very important in allbranches of engineering so( A. it is greatlystressed).197. Statistics deals with( B. gathering,classifying and using pieces ofinformation).198. An important aspect of statisticalmathematics is( A. probability) .199. Which is the main meaning of thepassage?( B. mathematics is veryimportant in all branches of engineering)Passage SevenCivil engineering projects are almostunique; that is, each has its own problemsand design features. Therefore, carefulstudy is given to each project even beforedesign work begins. The study includes asurvey both of topography and subsoilfeatures of the proposed site. It alsoincludes a consideration of possiblealternatives, such as a concrete gravitydam or an earth-fill embankment dam.The economic factors involved in each ofthe possible alternatives must also beweighed. Today, a study usually includes aconsideration of the environmental impactof the project. Many engineers, usuallyworking as a team that includes surveyors,specialists in soil mechanics, and expertsin design and construction, are involved inmaking these feasibility studies.200. Civil engineering projects are ( A.almost always distinctive)201. Each project( C. must be studiedcarefully)before design work begins202. The study, which must consider notonly structural features but also economicfactors and possible alternatives or otherchoices, is called( B. feasibility study) .203. Which of the following is true?(A.today civil engineering project needconsider the environmental impact of theproject )Passage EightClearing the site precedes all grading andmost other construction operations. Siteclearing in rural areas may sometimesmerely require that glass, shrubs, andother plants or crops be removed.However, it sometimes can involve removing trees and tree stumps and disposing of the debris. The accepted procedure is to remove practically all vegetable matter from the original ground and from fill material, since, if allowed to remain; it may decay and leave voids that result in settlement. Selective clearing in adjoining areas may at times be required. 204. According to the passage, which is the main topic?( B. site clearing)205. According to the passage, ( B. crops) is NOT be removed in rural areas.206. If all vegetable remained,( C. it may decay and leave voids).207. Sometimes it is required clearing( A. adjacent areas) .Passage NineVehicular safety design usually centers on protecting the driver and his passengers in case an accident occurs due to some other failure in the highway system. Examples of this type of design are safety belts and shoulder harnesses, safer door latches, non-shattering windshields, and energy absorbing steering columns. Improvements are made constantly in the parts of a vehicle which are obvious to the driver. These parts include windshield wipers, headlamps, brakes, steering suspension, and the exhaust system. The introduction of front and rear directional signals contributes greatly to motor vehicle safety. Stop lights, backup lights, and four-way emergency flashers also aid in vehicle safety. Four-way emergency flashers have become standard equipment for vehicles.208. According to the passage, which is NOT mentioned?( C. brake pedal)209. According to the passage, which becomes standard equipment forvehicles?( A. four-way emergencyflashers)210. Which of the following is true?( B.Vehicular safety design usually centers onprotecting the passengers and the personswho drives the vehicles)211. According to the passage, whichdesign is described?( A. vehicular safety)Passage TenIn the 1930s engineers found that superiorembankments could be constructed byspreading the material in relatively thinlayers and compacting it at moisturecontent close to optimum. Theimprovement resulted largely becausegreater density was obtained, whichresulted in higher “strength”in the soilmass and in decreased settlement andrutting. Layered construction alsoproduced greater uniformity in thematerial itself and in its density andmoisture content. This was beneficialsince any subsequent consolidation orswelling would be relatively uniform.212. In the 1930s engineers foundembankments could be constructed by( B.compacting it at a moisture content andspreading the material in relatively thinlayers)213. According to the passage, whichcause higher “strength”?( A. greaterdensity was obtained)214. Which of the following is true?( C.layered construction produced greaterunanimity in its density and moisturecontent)215. Which of the following words is theclosest meaning of ‘optimum’?( B. best)Passage ElevenAltogether, three forces can act on astructure: vertical—those that act up ordown; horizontal—those that act sideway;and those that act upon it with a rotatingor turning motion. Forces that act at anangle are combination of horizontal andvertical forces. Since the structuresdesigned by civil engineers are intendedto be stationary or stable, these forcesmust be kept in balance. The verticalforces, for example, must be equal to eachother. If a beam supports a load above, thebeam itself must have sufficient strengthto counterbalance that weight. Thehorizontal forces must also equal eachother so that there is not too much thrusteither to the right or to the left. And forcesthat might pull the structure around mustbe countered with forces that pull in theopposite direction.216. Horizontal forces( B. act sideways).217. Forces acting at an angle arecombination of( A. horizontal and verticalforces).218. The horizontal forces must equaleach other so that( C. there is not toomuch thrust either to the right or to theleft).219. Which of the following is true?( B.three forces acting on a structure must bekept in balance)Passage TwelveWe all enter into contracts almost everyday for the supply of goods, transportationand similar service, and in all theseinstances we are quite willing to pay forthe services we receive. Our needs inthese cases are comparatively simple andwe do not need to enter onto lengthy orcomplicated negotiations and no writtencontract is normally executed.。
piezoelectric effect 原理英文
piezoelectric effect 原理英文Piezoelectric Effect: Understanding the Principle Behind a Key TechnologyIntroductionThe piezoelectric effect is a fascinating phenomenon that has found wide-ranging applications in various fields, from sensors and actuators to medical devices and consumer electronics. This effect occurs in certain materials that exhibit a unique property – the generation of an electric charge in response to mechanical stress or the opposite effect, the generation of mechanical strain in response to an applied electric field. Understanding the principle behind the piezoelectric effect is crucial for harnessing its potential and developing innovative technologies. In this article, we delve into the fundamentals of the piezoelectric effect and explore its implications in modern science and industry.Historical BackgroundThe piezoelectric effect was first discovered by French physicists Jacques and Pierre Curie in 1880. They observed that certain crystals, such as quartz and Rochelle salt, produced electric charges when subjected to mechanical pressure. Thisphenomenon sparked a wave of research into the properties of piezoelectric materials and laid the foundation for the development of piezoelectric technology. Over the years, scientists have identified a wide range of materials that exhibit piezoelectric behavior, including ceramics, polymers, and composites.Principle of the Piezoelectric EffectAt the heart of the piezoelectric effect lies the concept of polarization, where the positive and negative charges within a material become displaced in response to an external stimulus. In piezoelectric materials, such as quartz or lead zirconate titanate (PZT), the crystal structure is asymmetric, with positive and negative charges distributed unevenly along certain axes. When a mechanical force is applied to the material, the crystal lattice deforms, causing the charges to shift and creating an electric field. This leads to the generation of an electric charge on the surface of the material, known as the direct piezoelectric effect.Conversely, when an electric field is applied to a piezoelectric material, the charges within the crystal lattice rearrange, resulting in a change in shape or mechanical strain, known as the inverse piezoelectric effect. This bidirectionalrelationship between mechanical stress and electric field forms the basis of piezoelectric transduction, where energy is converted between mechanical and electrical forms.Applications of the Piezoelectric EffectThe piezoelectric effect has revolutionized a wide range of industries, enabling the development of innovative devices and technologies. Some of the key applications of piezoelectric materials include:1. Sensors and Actuators: Piezoelectric sensors are widely used in industrial applications, such as measuring pressure, force, and acceleration. Likewise, piezoelectric actuators are employed in precision positioning systems, ultrasonic motors, and vibration control devices.2. Energy Harvesting: Piezoelectric materials can convert mechanical vibrations or ambient vibrations into electrical energy, making them ideal for energy harvesting applications in wearable devices, wireless sensors, and self-powered systems.3. Medical Devices: Piezoelectric transducers are used in medical imaging technologies, such as ultrasound andnon-destructive testing. Piezoelectric bone conduction devicesand piezoelectric actuators are also used in hearing aids and implantable medical devices.4. Consumer Electronics: Piezoelectric materials are found ina variety of consumer electronics products, including piezoelectric buzzers, acoustic sensors, and haptic feedback devices in smartphones and tablets.Future Prospects and ChallengesAs the demand for miniaturized, energy-efficient devices continues to grow, the piezoelectric effect holds great promise for future technological advancements. Researchers are exploring new materials, such as flexible and bio-compatible polymers, for unique applications in wearable electronics, biomedical implants, and energy-efficient devices. However, there are still challenges to overcome, such as improving the performance and durability of piezoelectric materials, optimizing energy conversion efficiency, and reducing costs for large-scale production.ConclusionThe piezoelectric effect is a powerful phenomenon that has transformed the way we interact with technology and the world around us. By understanding the principles behind this effectand exploring its diverse applications, we can unlock new opportunities for innovation and create a sustainable future. As we continue to push the boundaries of material science and engineering, the piezoelectric effect will undoubtedly play a key role in shaping the technologies of tomorrow.。
反应条件对产物晶型和形貌的影响以二氧化锰为例
反应条件对产物晶型和形貌的影响以二氧化锰为例王晨森，臧永军，李国宝，杨伏宇（皖西学院生物与制药工程学院，安徽六安237012）摘要：本文采用水热法制备了一系列的二氧化锰粉末状晶体。
探索了反应温度、氧化剂浓度、压力等因素对二氧化锰晶型、结晶度与形貌的影响及其内在联系。
结果表明反应温度、氧化剂浓度、压力对二氧化锰晶型均有影响，氧化剂浓度对其晶型影响尤为明显。
温度对形貌影响较为明显。
在晶型相同情况下，二氧化锰结晶度正相关于其形貌规整度。
关键词：二氧化锰水热法晶型结晶度形貌中图分类号：TQ110文献标识码：A文章编号：1003-4862（2017）11-0018-04Effect of Reaction Conditions on Crystal Form and Morphology of Products-Taking Manganese Dioxide as an ExampleWang Chensen,Zang Yongjun,Li Guobao,Yang Fuyu(School of Biology and Pharmaceutical Engineering,West Anhui University,Luan237012,Anhui,China) Abstract:In this paper,a series of manganese dioxide powders are prepared by hydrothermal method.The effects of reaction temperature,oxidant concentration and pressure on the crystal form,crystallinity and morphology of manganese dioxide are investigated,and the relationship between crystal morphology, crystallinity and morphology is explored.The results show that the reaction temperature,oxidant concentration and pressure have effect on the crystal form of manganese dioxide.The effect of oxidant concentration on crystal form is obvious,and the effect of temperature on morphology is obvious.In the same crystal form case,the crystallinity of manganese dioxide is about its shape regularity. Keywords:manganese dioxide;hydrothermal method;crystal form;crystalline;morphology0引言二氧化锰(MnO2)作为一种价格低廉、储量丰富、无毒无污染无机功能材料，广泛地应用于电极材料、催化等领域[1-2]。
吸收能剪切断面率和测膨胀值英文
吸收能剪切断面率和测膨胀值英文English:The absorption rate, also known as the absorption coefficient, is a measure of the ability of a material to absorb a fluid or gas in relation to the material's mass. It is typically expressed as a percentage or a decimal value. The shear cut-off rate, on the other hand, is a measure of the ability of a material to resist shear forces and maintain its structural integrity when subjected to cutting or shearing. This is important in various industries such as construction, automotive, and manufacturing where materials need to maintain their shape and stability during manufacturing processes or usage. Meanwhile, the expansion value, also known as the coefficient of thermal expansion, is a measure of the fractional change in dimension of a material per unit change in temperature. It is an important property to consider in the design and engineering of products, especially in applications where temperature variations can impact the performance and longevity of the material.Translated content:吸收率，也称为吸收系数，是衡量材料对流体或气体吸收能力的能力，与材料的质量相关。
Fracture Mechanics and Fatigue
Fracture mechanics and fatigue are crucial concepts in the field of materials science and engineering. Fracture mechanics deals with the study of how materials behave when subjected to stress, particularly focusing on the initiation and propagation of cracks. On the other hand, fatigue is the phenomenon where materials fail due to repeated loading and unloading cycles, leading to the gradual growth of cracks until catastrophic failure occurs. Understanding these phenomena is essential for designing safe and reliable structures in various industries, such as aerospace, automotive, and civil engineering. One of the key aspects of fracture mechanics is the concept of stress intensity factor, which quantifies the stress field near the tip of a crack and predicts the likelihood of crack propagation. By analyzing the stress distribution around a crack, engineers can assess the critical conditions under which a crack will grow and ultimately lead to failure. This knowledge is crucial for determining the safety margins of structures and components, ensuring that they can withstand the expected loading conditions throughout their service life. Fatigue, on the other hand, poses a different challenge for materials engineers. Unlike static loading, fatigue loading involves cyclic stress variations that can lead to crack initiation and propagation even at stress levels below the material's ultimate strength. This phenomenon is particularly critical in applications where components are subjected to repeated loading, such as aircraft wings, automotive suspension systems, and offshore structures. By studying the fatigue behavior of materials, engineers can predict the fatigue life of a component and implement strategies to mitigate fatigue failure, such as improving material quality, introducing surface treatments, or redesigning the component geometry. In practice, fracture mechanics and fatigue analysis are often combined to assess the structural integrity of complex systems. Engineers use advanced modeling techniques, such as finite element analysis and computational simulations, to predict the behavior of materials under different loading conditions. By incorporating experimental data and theoretical models, engineers can optimize the design of structures and components to minimize the risk of failure due to fracture or fatigue. This integrated approach allows engineers to balance performance, cost, and safetyconsiderations in the design process, ensuring that structures meet the required standards and regulations. Despite the advancements in materials science and engineering, challenges still exist in predicting and preventing fracture and fatigue failures. The complex nature of material behavior, combined with the variability of loading conditions and environmental factors, makes it difficult to accurately predict the lifetime of structures and components. Moreover, unexpected failure events can have catastrophic consequences, leading to injuries, financial losses, and damage to the environment. As such, ongoing research and development efforts are focused on improving the understanding of fracture mechanics and fatigue behavior, developing new materials with enhanced durability and reliability, and implementing advanced testing and monitoring techniques to detect early signs of damage. In conclusion, fracture mechanics and fatigue are fundamental concepts in materials science and engineering that play a crucial role in ensuring the safety and reliability of structures and components. By studying the behavior of materials under different loading condition likelihood of crack initiation and propagation, assess the fatigue life of components, and optimize the design of structures to minimize the risk of failure. While challenges exist in predicting and preventing fracture and fatigue failures, ongoing research and development efforts are aimed at improving our understanding of material behavior and developing innovative solutions to enhance the durability and performance of engineering systems. By addressing these challenges, engineers can continue to push the boundaries of materials science and engineering, creating safer and more sustainable structures for the future.
Investigating the Effect of Aging on Materials
Investigating the Effect of Aging onMaterialsIntroductionMaterials are essential for the development of modern society, they provide us with the necessary tools to build our buildings, create our vehicles and develop new technologies. But materials are not invincible, they can degrade over time due to several factors, including exposure to the environment, stress, and aging. Therefore, it is important to investigate the effect of aging on materials to better understand how they will perform over time and ensure their longevity.What is aging?Aging is a natural process that affects all materials, including metals, polymers, ceramics, and composites. It can be defined as the gradual deterioration of material properties due to various mechanisms such as chemical reactions, physical processes like diffusion, and structural changes on the atomic and molecular levels.The aging process is influenced by several factors, including temperature, humidity, exposure to UV radiation, and other environmental factors. Additionally, mechanical and physical stresses can also cause materials to age more quickly.The Effects of Aging on MaterialsAging can affect materials in several ways. One of the most significant effects is the degradation of mechanical properties, including strength, ductility, and toughness. Aging can cause microstructural changes that affect the material's ability to withstand stress and deformation.For example, metals can age due to corrosion, which can cause cracks and other defects that weaken the material's strength. Polymers can also undergo aging through oxidation, which can result in cracking, embrittlement, and loss of strength.Aging can also affect a material's thermal and electrical properties. For example, thermal conductivity may decrease due to the accumulation of impurities or changes in the microstructure. Additionally, aging can cause materials to become less electrically conductive.Methods of Investigating AgingThere are several methods for investigating the effect of aging on materials, including field experiments, laboratory testing, and simulation.Field experiments involve monitoring the performance of materials in real-world environments over a long period of time. This method is useful for investigating the effects of aging on materials in actual service conditions.Laboratory testing involves exposing materials to specific environmental conditions, such as temperature, humidity, and UV radiation, and monitoring their properties over time. This method is useful for simulating the effects of aging on materials in controlled conditions.Simulation involves predicting the aging behavior of materials using computer models. This method is useful for investigating the effect of aging on materials that are difficult or expensive to test in the laboratory or field.ConclusionThe effect of aging on materials is an important area of research that has implications for many industries. Understanding how materials age can help to develop more durable and reliable materials, which can enhance the safety and performance of critical infrastructure and other applications where materials are used. Methods of investigating the effect of aging on materials are diverse, and a combination of laboratory testing, field experiments, and simulation is often used to gain a comprehensive understanding of the aging process.。
半导体一些术语的中英文对照
半导体一些术语的中英文对照离子注入机ion implanterLSS理论Lindhand Scharff and Schiott theory 又称“林汉德-斯卡夫-斯高特理论”。
沟道效应channeling effect射程分布range distribution深度分布depth distribution投影射程projected range阻止距离stopping distance阻止本领stopping power标准阻止截面standard stopping cross section 退火annealing激活能activation energy等温退火isothermal annealing激光退火laser annealing应力感生缺陷stress-induced defect择优取向preferred orientation制版工艺mask-making technology图形畸变pattern distortion初缩first minification精缩final minification母版master mask铬版chromium plate干版dry plate乳胶版emulsion plate透明版see-through plate高分辨率版high resolution plate, HRP超微粒干版plate for ultra-microminiaturization 掩模mask掩模对准mask alignment对准精度alignment precision光刻胶photoresist又称“光致抗蚀剂”。
负性光刻胶negative photoresist正性光刻胶positive photoresist无机光刻胶inorganic resist多层光刻胶multilevel resist电子束光刻胶electron beam resistX射线光刻胶X-ray resist刷洗scrubbing甩胶spinning涂胶photoresist coating后烘postbaking光刻photolithographyX射线光刻X-ray lithography电子束光刻electron beam lithography离子束光刻ion beam lithography深紫外光刻deep-UV lithography光刻机mask aligner投影光刻机projection mask aligner曝光exposure接触式曝光法contact exposure method接近式曝光法proximity exposure method光学投影曝光法optical projection exposure method 电子束曝光系统electron beam exposure system分步重复系统step-and-repeat system显影development线宽linewidth去胶stripping of photoresist氧化去胶removing of photoresist by oxidation等离子［体］去胶removing of photoresist by plasma 刻蚀etching干法刻蚀dry etching反应离子刻蚀reactive ion etching, RIE各向同性刻蚀isotropic etching各向异性刻蚀anisotropic etching反应溅射刻蚀reactive sputter etching离子铣ion beam milling又称“离子磨削”。
提高抗疲劳寿命的工艺方法英文
提高抗疲劳寿命的工艺方法英文提高抗疲劳寿命的工艺方法英文1. Surface treatment: The surface of the material can be treated by shot peening or polishing, which can improve the resistance to fatigue and reduce the stress concentration on the surface.2. Heat treatment: Heat treatment can improve the fatigue resistance of materials by changing their microstructure and mechanical properties. For example, quenching and tempering can improve the strength and toughness of materials, while carburizing can improve their wear resistance.3. Material selection: Choosing materials with high fatigue strength and toughness, such as titanium and nickel alloys, can improve the fatigue resistance of components.4. Design optimization: The design of components can be optimized to reduce stress concentrations and improve load distribution, which can reduce the risk of fatigue failure.5. Lubrication: Proper lubrication can reduce friction and wear, which can improve the fatigue resistance of components.6. Maintenance and inspection: Regular maintenance and inspection can detect and repair fatigue cracks before they lead to catastrophic failure, which can significantly improvethe fatigue life of components.。
应力集中公式用于任何形状的缺口在圆试样在张力下弯曲
Stress concentration formulae useful for any shape of notch in a round test specimen under tension and under bendingN.A.N O DA a n d Y.TA K A S EDepartment of Mechanical Engineering,Kyushu Institute of T echnology,Kitakyushu804-8550,JapanReceived infinal form2June1999A B S T R A C T In this work stress concentration factors,K t,for a round bar with a circular-arc orV-shaped notch are considered on the basis of exact solutions for special cases andaccurate numerical results.Then,a set of K t formulae useful for any shape of notch isproposed.The conclusions can be summarized as follows.(i)For the limiting cases of deep(d)and shallow(s)notches,the body force methodis used to calculate the K t values.Then,the formulae are obtained as K t d and K t s.(ii)On the one hand,upon comparison of K t and K t d it is found that K t is nearlyequal to K t d if the notch is deep or blunt.(iii)On the other hand,if the notch is sharp or shallow,K t is mainly controlled byK t s and the notch depth.(iv)The notch shape is classified into several groups according to the notch radiusand notch depth.Then,the least-squares method is applied for the calculation of K t/K t dand K t/K t s.(v)Finally,a set of convenient formulae is proposed that are useful for any shape ofnotch in a round test specimen.The formulae give SCFs with<1%error for anyshape of notch.Keywords stress concentration factor;fatigue test specimen;V-shaped notch;notchformulae;tension;bending;body force method.N O M E N C L A T U R E a=radius of minimum sectionD=cylindrical diameter of maximum sectionK t=stress concentration factor(SCF)based on the minimum sectionK t d=SCF of deep V-shaped notchK t E=SCF of an elliptical hole in an infinite plate under uniform tension(=1+2ǰ(t/r)K t H=SCF of hyperboloidal notchK t s=SCF of60°V-shaped notch in a semi-infinite platet=depth of notchx=a/r when a/r∏1.0and=2−r/a when r/a∏1.0D K th=threshold stress intensity factor rangeg=ǰl=relative notch depth,=2t/Dn=Poisson’s ratio(=0.3)j=ǰt/rr=root radius of notchnents cannot be explained only from the stress concen-I N T R O D U C T I O Ntration factor K t with the fatigue limit of a plain The stress concentration of a notched round bar isspecimen.Depending on the depth and sharpness of especially important in terms of a fatigue test specimen.notches,the effect of the geometrical dimension ofnotches on the fatigue strength is different.In a number It is known that the fatigue strength of notched compo-©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct22,1071–108210711072N.A.N O D A a n d Y.TA K A S Eof papers,1–4Miller and co-workers have suggested that K t is nearly equal to K t d if the notch is deep or blunt. notches subjected to fatigue are essentially of two formsFourth,the notch shape is classified into several groups in which the following points apply.according to the notch radius and notch depth.Finally,a set of convenient formulae useful for any shape of 1Shallow notches under fatigue are largely controllednotch is proposed by applying the least-squares method by the root radius r and the fatigue limit of thefor each group.The set of formulae gives SCFs with material.<1%error for any shape of notch.2Sharp notches under fatigue are largely controlled byj=ǰ(t/r)where t is the notch depth and the fatiguelimit as expressed by the LEFM parameter D K th.S T R E S S C O N C E N T R A T I O N F A C T O R S O F S H A R PO R S H A L L O W N O T C H E ST o clarify the fatigue notch mechanism in detail,it isnecessary to use accurate K t values when using a highly Consider the stress concentration factor K t of a60°V-shaped notch as shown in Fig.1(c).In this case the developed experimental technique.However,to estimate stress concentration factors SCF of the sharp notch is mainly controlled by the SCF (SCFs)for notched bars,Neuber’s ingenious formulaeof a60°V-shaped notch in a semi-infinite plate K t s have been used for more than40years.5They are having the same shape ratio t/r.10The ratio K t/K t s is convenient for engineering application because:shown in Fig.2.In Fig.2the line for r/a 0is obtainedfrom results when r/a is small;e.g.r/a=0.1and0.2 1they have simple forms;andwhich confirm that the two results are in agreement to 2they give approximate values for any shape of notch.the third digit.The K t s approximation is better in tension Previously,the authors have proposed more accuratethan in bending.In Fig.2,we can see the following. formulae6using the results of the body force method7and correcting Neuber’s values.However,the formulae1In sharp notches(r/a∏0.1),the value of K t/K t s is are only useful for a certain range of notch shape becausemainly determined by2t/D alone.The value of K t can of the restriction of the body force method of appli-be obtained from K t s in the following range depending cation.8,9Generally,there is no numerical method thaton the loading conditions,i.e.is effective for analysing any shape of the notch with(i)tension:2t/D∏0.8,(ii)bending:2t/D∏0.4.<1%error.In other words,it is difficult to obtainaccurate stress concentration factors when the notch2In shallow notches(2t/D∏0.02),the value of K t/K t s root radius is extremely large or extremely small.is controlled by2t/D for a wide range of a/r values,i.e. In this study,first,the values of K t for a round bar(i)tension:the value of K t/K t s is determined by2t/D with a circular-arc or V-shaped notch are considered foralone,when a/rÁ0.01,limiting cases of deep and shallow notches,K t d and K t s.(ii)bending:the value of K t/K t s is within a small Second,it is found that if the notch is sharp or shallow,range,when a/rÁ0.02and2t/D∏0.02, e.g. K t is mainly controlled by K t s and the notch depth.0.938∏K t/K t s∏0.968.3The stress concentration factor of a blunt and a Third,upon comparison of K t and K t d,it is found thatFig.1Round specimens with a circular-arcor a V-shaped notch:(a)extremely bluntnotch;(b)ordinary notch;and(c)extremelysharp notch.©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct22,1071–1082S T R E S S C O N C E N T R AT I O N F O R M U L A E 1073Fig.2K t /K t s versus 2t /D :(a)tension;(b)bending.shallow notch (2t /D ∏0.02)will be considered in the when a /r 2is obtained by extrapolation with corre-sponding good accuracy;e.g.an extrapolated value from next section,but can be estimated as follows.(i)tension:a /r ∏0.01,K t =(1.000–1.006),a /r =3.333and 5,and another extrapolated value from a /r =5and 10coincide with each other to the third (ii)bending:a /r ∏0.02,K t =(1.000–1.005).digit in some cases.Using the K t d formula,the ratio K t /K t d is shown in S T R E S S C O N C E N T R A T I O N F A C T O R S O F B L U N T Fig.5.From the comparison between Fig.5and Fig.3,A N D D E E P N O T C H E Sthe K t d formula is found to give a better approximation for K t especially in the range of (1∏r /a ∏0).The K t d Here,the SCF is considered for blunt and deep notches.Figure 3shows K t /K t H $1for a wide range of notches approximation is better in bending than in tension as shown in Fig.5.From Fig.5,the K t d approximation is under tension and bending;i.e.the SCF of a deep hyperboloidal notch K t H can be used as a good approxi-useful in the following range.mate formula.11From Fig.3it is found that the deep notch (2t /D Á0.7)can be estimated as an infinitely deep 1T ension.(i)2t /D Á0.8,10∏a /r ∏2V-notch as shown in Fig.4.T able 1shows the ratio K t /K t H when 2t /D =0.7,0.8and 1.000∏K t /K t d ∏1.004,(ii)0.3∏2t /D ∏1.0,0∏a /r ∏10and 0.9.With increasing notch depth,K t /K t H approaches limiting values.I.e.as 2t /D 1.0,K t /K t H (0.992–1.060)and 0.951∏K t /K t d ∏1.034,(iii)0.02∏2t /D ∏0.3,in tension,and K t /K t H (0.998–1.050)in bending.The ratio K t /K t H does not approach unity because of the 0∏a /r ∏0.5;0.956∏K t /K t d ∏1.029.2Bending.difference in the notch shape,i.e.the 60°V-shape and hyperboloid.In T able 1the limiting values of K t d /K t H (i)2t /D Á0.4,10∏a /r ∏2and 0.996∏K t /K t d ∏1.001,are obtained using the convergence of K t /K t H when 2t /D 1.0.The approximate formulae for a deep 60°(ii)0.2∏2t /D ∏1.0,0∏a /r ∏10and 0.958∏K t /K t d ∏1.005,V-shaped notch can be expressed as a function of the parameter x in T able 1by applying the least-squares (iii)0.02∏2t /D ∏0.2,0∏a /r ∏0.8;and 0.955∏K t /K t d ∏1.007.method to the results given in T able 1.The K t /K t H value©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct 22,1071–10821074N.A.N O D A a n d Y.TA K A S ES T R E S S C O N C E N T R A T I O N F A C T O R S O F O T H E RN O T C H E SHere,the stress concentration factor K t is considered forthe remaining region:for tension:0.1∏r/a∏2.0and0.02∏2t/D∏0.3;for bending:0.1∏r/a∏1.2and0∏2t/D∏0.2.In this region,as shown in Fig.2the value of K t/K t s ismainly determined by2t/D and exists in a narrow range.Figure6shows(K t/K t s)/[K t/K t s]r/a=1.0in tension and(K t/K t s)/[K t/K t s]r/a=0.6in bending.They are useful inthe following range.1T ension:0.1∏r/a∏2.0and0.02∏2t/D∏0.3;0.97∏(K t/K t s)/([K t/K t s]r/a=1.0)∏1.03.2Bending:0.1∏r/a∏1.2and0∏2t/D∏0.2;0.96∏(K t/K t s)/([K t/K t s]r/a=0.6)∏1.05.A S E T O F S C F F O R M U L A E U S E F U L F O R A N YS H A P E O F N O T C HFrom the above discussion,any shape of notch has beenclassified into one of the groups shown in Fig.7.Then,the least-squares method is applied to each region shownin Fig.7.Finally,a set of accurate formulae for thewhole range of notch shapes is obtained.The results areas follows.SCF of a60°V-shaped notch or circular-arc notch in Fig.3K t/K t H versus a/r or r/a:(a)tension;(b)bending.a semi-infinite plate Kt sThe limiting SCF of shallow notch K t K t s in Fig.1when a and D 2.The K t s formula can be expressedas in Eq.(1)below.Figure8shows the value of Eq.(1)from the results of the body force method.K t s/K t E=1.000−0.127j+0.2908j2−0.1420j3(0∏j∏1)(1a)K t s/K t E=1.148−0.160g−0.0345g2+0.0693g3(0∏g∏1)(1b)j=ǰt/r,g=ǰr/t,K t E=1+2ǰt/r(1c)SCF of a sharp or shallow notch K t1T ension.Region1in Fig.7(a):r/a∏0.1and2t/D∏0.8,or a/rÁ0.01and2t/D∏0.02.The SCF for a sharp Fig.4Geometrical forms for K t$K t d when2t/DÁ0.7.or shallow notch in tension can be expressed by Eq.(2)below.The value of Eq.(2)is shown in Fig.9(a).©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct22,1071–1082S T R E S S C O N C E N T R AT I O N F O R M U L A E1075 Table1K t/K t H when2t/D 1.0x a/r r/a2t/D=0.72t/D=0.82t/D=0.92t/D 1.0Tension0.0000.00020.1000.10010.000.999 1.000 1.000 1.0000.2000.200 5.0000.9980.9980.9980.9980.3000.300 3.3330.9960.9960.9960.9960.4000.400 2.5000.9950.9940.9940.9940.5000.500 2.0000.9940.9930.9930.9930.6000.600 1.6670.9960.9930.9920.9920.7000.700 1.4290.9970.9940.9930.9930.8000.800 1.2500.9980.9950.9940.9940.9000.900 1.111 1.0010.9970.9950.9951.000 1.000 1.000 1.0020.9990.9970.9971.000 1.000 1.000 1.0020.9990.9970.9971.100 1.1110.900 1.005 1.0010.9990.9991.200 1.2500.800 1.008 1.004 1.003 1.0031.300 1.4290.700 1.012 1.008 1.006 1.0061.400 1.6670.600 1.017 1.013 1.012 1.0121.5002.0000.500 1.023 1.019 1.018 1.0181.6002.5000.400 1.030 1.026 1.026 1.0261.700 3.3330.300 1.038 1.035 1.0351.800 5.0000.200 1.046 1.045 1.0451.90010.000.100 1.053 1.0532.00020.000 1.060Bending0.0000.00020.1000.10010.000.9970.9990.9990.9990.2000.200 5.000 1.0000.9980.9980.9980.3000.300 3.3330.9980.9980.9980.9980.4000.400 2.5000.9980.9990.9990.9990.5000.500 2.000 1.000 1.0000.9990.9990.6000.600 1.667 1.000 1.000 1.000 1.0000.7000.700 1.429 1.001 1.001 1.001 1.0010.8000.800 1.250 1.002 1.002 1.002 1.0020.9000.900 1.111 1.003 1.003 1.003 1.0031.000 1.000 1.000 1.004 1.004 1.004 1.0041.000 1.000 1.000 1.004 1.004 1.004 1.0041.100 1.1110.900 1.005 1.005 1.005 1.0051.200 1.2500.800 1.006 1.006 1.006 1.0061.300 1.4290.700 1.008 1.008 1.008 1.0081.400 1.6670.600 1.010 1.010 1.010 1.0101.5002.0000.500 1.013 1.013 1.013 1.0131.6002.5000.400 1.016 1.017 1.017 1.0171.700 3.3330.300 1.021 1.022 1.0221.800 5.0000.200 1.027 1.028 1.0281.90010.000.100 1.038 1.0382.00020.000 1.050K t/K t s=0.99981−1.5611l−2.0531l2+31.554l3K t/K t s=1.0000−3.4188l+14.016l2−69.430l3+284.03l4−780.07l5+1342.0l6−1382.7l7−137.39l4+313.02l5−395.19l6+261.31l7−70.691l8(2)+779.25l8−184.65l9(3) 2Bending.Region1in Fig.7(b):r/a∏0.1and2t/D∏0.4.The Region6in Fig.7(b):0.02∏a/r∏0.8(i.e.when SCF for a sharp notch in bending can be expressed0.02∏x∏0.8)and2t/D∏0.02.The SCF for a shallow by Eq.(3)below.The value of Eq.(3)is shown in notch in bending can be expressed by Eq.(4)below.The value of Eq.(4)is shown as the same line of Fig.9(b).©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct22,1071–10821076N.A.N O D A a n d Y.TA K A S E(a)(b)Fig.5K t/K t d versus a/r or r/a:(a)tension;(b)bending. Eq.(3)in Fig.9(b).K t/K t s=1.0000−(0.96873+32.614x−233.80x2+811.76x3−1423.4x4+1222.9x5−410.16x6)l(4) SCF of a blunt and shallow notch K t1T ension.Region6in Fig.7(a):a/r∏0.01and2t/D∏0.02K t$1.003(5)(a)(b)Fig.6(K t/K t s)/([K t/K t s]r/a=1.0)versus2t/D for tension,and2Bending.(K t/K t s)/([K t/K t s]r/a=0.6)versus2t/D for bending.Region7in Fig.7(b):a/r∏0.02and2t/D∏0.02K t$1.002(6)below.Figure10shows the values of Eqs(7)and(8)from the results of the body force method.SCF of a deep60?V-shaped notch K t d as shown in1T ension.Fig.4(b)K t d/K t H=1.0011−0.025485x+0.015727x2The limiting SCF of a deep notch K t K t d when t 2.The K t d formula can be expressed by Eqs(7)and(8)+0.006131x3(7a)©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct22,1071–1082S T R E S S C O N C E N T R AT I O N F O R M U L A E 1077SCF of a sharp and deep notch,K t1T ension.Region 2in Fig.7(a):r /a ∏0.1and 2t /D Á0.8K t /K t d $1.002(9)2BendingRegion 2in Fig.7(b):r /a ∏0.1and 2t /D Á0.4K t /K t d $0.997(10)SCF of a deep notch,K t1T ension.Region 3in Fig.7(a):2t /D Á0.3and a /r ∏10(i.e.when 0∏x ∏1.9).The SCF of a deep notch can be expressed by Eq.(11)below.Figure 11shows the values of Eq.(11)K t /K t d=1.0003−0.004428l +0.0091157l 2−0.0045697l 3+(0.11519−0.46435l +0.63297l 2−0.28290l 3)x +(0.010653+0.34748l −0.85221l 2+0.49036l 3)x 2+(−0.06707+0.061199l +0.12722l 2−0.11927l 3)x 3(11)(a)(b)2Bending.Fig.7Classification of notch shape in a round bar.(a)Under Region 3in Fig.7(b):2t /D Á0.2and a /r ∏10(i.e.when tension.Region 1:sharp or shallow notch.Region 2:sharp and 0∏x ∏1.9).The SCF of a deep notch can be expressed deep notch.Region 3:deep notch.Region 4:blunt notch.by Eq.(12)below.Figure 11shows the values of Eq.(12)Region 5:ordinary notch.Region 6:blunt and shallow notch.(b)Under bending.Region 1:sharp or shallow notch.Region 2:K t /K t d =0.99583+0.00027062l +0.012355l 2sharp and deep notch.Region 3:deep notch.Region 4:blunt notch.Region 5:ordinary notch.Region 6:shallow notch.+0.13037l 3−0.30457l 4+0.16578l 5Region 7:blunt and shallow notch.+(0.24827−2.6149l +12.449l 2−27.871l 3+28.293l 4−10.502l 5)xK t H =(1/N ){(a /r )ǰa /r +1+(0.5+n )(a /r )+(−0.69237+7.7422l −37.365l 2+(1+n )(ǰa /r +1+1)}(7b)+81.715l 3−80.203l 4+28.797l 5)x 2+(0.59961−6.4408l +30.561l 2N =a /r +2n ǰa /r +1+2(7c)−65.732l 3+63.410l 4−22.393l 5)x 32Bending.+(−0.18234+1.8160l −8.1768l 2K t d /K t H =0.99744+0.014732x −0.024870x2+17.016l 3−16.033l 4+5.5587l 5)x 4(12)+0.014924x3(8a)K t H =(1/N )(3/4)(ǰa /r +1+1)SCF of a blunt notch K t×{3(a /r )−(1−2n )ǰa /r +1+4+n }(8b)1T ension.Region 4in Fig.7(a):a /r ∏0.5(i.e.when 0∏x ∏0.5)N =3(a /r +1)+(1+4n )ǰa /r +1and 0.02∏2t /D ∏0.3.The SCF of a blunt notch in tension can be expressed by Eq.(13)below.Figure 12+(1+n )/(ǰa /r +1+1)(8c)©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct 22,1071–10821078N.A.N O D A a n d Y.TA K A S E(a)(b)Fig.8K t s/K t E versus r/t or t/r.shows the values of Eq.(13)K t/K t d=1.0007−0.0071666l+0.0012083l2+0.049476l3+(0.073591−0.49666l+0.37944l2+0.97121l3)x +(−0.83503+19.753l−103.43l2+164.69l3)x2+(0.78512−23.474l+132.20l2−217.06l3)x3(13) 2Bending.Region4in Fig.7(b):a/r∏0.8(i.e.when0∏x∏0.8) and0.02∏2t/D∏0.2.The SCF of a blunt notch in bending can be expressed by Eq.(14)below.Figure 12(a)(b)shows the values of Eq.(14)Fig.9K t/K t s versus2t/D:(a)tension;(b)bending.K t/K t d=1.000−0.014793l+0.070689l2+(0.095073−1.1067l+2.9132l2)xSCF of other notches+(−0.42518+6.8626l−22.079l2)x21T ension.Region5in Fig.7(a):0.1∏r/a∏2.0(i.e.when +(0.26412−4.8073l+15.994l2)x3(14)©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct22,1071–1082S T R E S S C O N C E N T R AT I O N F O R M U L A E1079(a)(b)(a)(b)Fig.10K t d /K t H versus a /r or r /a :(a)tension;(b)bending.Fig.11K t /K t d versus a /r or r /a :(a)tension;(b)bending.0.5∏x ∏1.9)and 0.02∏2t /D ∏0.3.The SCF of other 2Bending.notches in tension can be expressed by Eq.(15a)below.Region 5in Fig.7(b):0.1∏r /a ∏1.2(i.e.when Figure 13shows the values of Eq.(15a).The value of 0.8∏x ∏1.9)and 2t /D ∏0.2.The SCF of other notches Eq.(15b)is shown in Fig.9(a).in bending can be expressed by Eq.(16)below.Figure 13shows the values of Eq.(16a).The value of Eq.(16b)is K t /K t s ={0.99750−0.009307(r/a)+0.0082361(r/a)2shown in Fig.9(b).−0.0021749(r/a)3K t /K t s ={1.0002−0.0026876(r/a)+0.0070447(r/a)2+[−0.012636+0.49854(r/a)−0.66661(r/a)2−0.0061187(r/a)3+0.0017046(r/a)4+0.20013(r/a)3]l+[0.18110+0.75835(r/a)−4.7083(r/a)2+[0.61979−5.7347(r/a)+7.6371(r/a)2+6.3820(r/a)3+2.5358(r/a)4]l −2.2656(r/a)3]l 2+[−5.0005−8.5836(r/a)+76.517(r/a)2+(−2.7417+14.305(r/a)−18.013(r/a)2−105.46(r/a)3+42.876(r/a)4]l 2+5.4021(r/a)3]l 3}([K t /K t s ]r/a =1.0)(15a)+[15.016+26.229(r/a)−237.78(r/a)2[K t /K t s ]r/a =1.0=1.0046−1.7334l +1.1221l 2+4.9028l 3+333.28(r/a)3−136.89(r/a)4]l 3}−17.228l 4+20.570l 5−8.6378l 6(15b)×([K t /K t s ]r/a =0.6)(16a)©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct 22,1071–10821080N.A.N O D A a n d Y.TA K A S E(a)(b)(a)(b)Fig.13(K t/K t s)/([K t/K t s]r/a=1.0)versus2t/D for tension and Fig.12K t/K t d versus a/r:(a)tension;(b)bending.(K t/K t s)/([K t/K t s]r/a=0.6)versus2t/D for bending.©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct22,1071–1082S T R E S S C O N C E N T R AT I O N F O R M U L A E 1081[K t /K t s ]r/a =0.6=0.99826−3.3823l +14.184l 2−51.123l 3+118.36l 4−160.19l 5+114.63l 6−33.480l 7(16a)As stated above,the set of formulae given by Eqs (1)–(16)give accurate stress concentration factors,K t for the whole range of notches.Figure 14shows an example of a SCF chart obtained by these equations.C O N C L U S I O N SIn this paper,stress concentration formulae,K t ,of a round bar with a circular-arc and a V-shaped notch under tension and under bending are considered on the basis of the exact solutions now available for the limiting cases together with accurate numerical results obtained by using the body force method.The conclusions can be summarized as follows.1For the limiting cases of deep and shallow notches,the body force method was used to calculate the stress concentration factors (SCF).Then,the formulae for deep (d)and shallow (s)notches were obtained as K t d and K t s values.2On one hand,upon comparison of K t and K t d ,it was found that K t is nearly equal to K t d if the notch is deep or blunt.3On the other hand,if the notch is sharp or shallow,K t is mainly controlled by K t s and the notch depth.4The notch shape can be classified into several groups according to the notch radius and notch depth.The least-squares method can be applied for the calculation of K t /K t d and K t /K t s .5Finally,a set of convenient formulae is proposed that are useful for any shape of notch in a round test specimen.The formulae give SCFs with <1%error for any shape of notch.AcknowledgementsThe authors wish to express their gratitude for the guidance and encouragement received from Prof.H.Nisitani.They also wish to express their thanks to the members of their group,especially Mr M.Shinozaki and Mr K.Kanzaki,who carried out much of the construc-tional work.R E F E R E N C E Sler (1993)Material science perspective of metal fatigue resistance.Mater.Sci.T echnol.9,453–462.ler (1997)In:The Three Thresholds for Fatigue Regimes in Notched Components (Edited by R.S.Piascik,J.C.Newman and N.E.Dowling),ASTM STP 1296,pp.267–286.(a)(b)Fig.14Stress concentration factors of a notched round bar:(a)tension;(b)bending.1082N.A.N O D A a n d Y.TA K A S E3R.A.Smith and ler(1977)Fatigue cracks at notches.9Y.Murakami,N.-A.Noda and H.Nisitani(1986)Application Int.J.Mech.Sci.19,11–22.of body force method to the axi-symmetric body under bending: 4R. A.Smith and ler(1978)Prediction of fatigue II.Stress concentration of a cylindrical bar with a semi-elliptical regimes in notched components.Int.J.Mech.Sci.20,201–206.notch under bending.Int.J.Solids Structures22,39–53.5H.Neuber(1957)Kerbspannungslehre,Springer,Berlin.10H.Nisitani and N.-A.Noda(1985)Study on the stress concen-6N.-A.Noda,M.Sera and Y.T akase(1995)Stress concentrationtration problem of a cylindrical bar having a60°V-shaped factors for round andflat test specimens with notches.Int.J.circumferential groove under tension.Trans.Jpn Soc.Mech.Fatigue17,163–178.Engrs51,54–62(in Japanese).7H.Nisitani(1967)The two-dimensional stress problem solved11N.-A.Noda and H.Nisitani(1990)Stress concentration analysis using an electric digital computer.J.Jpn Soc.Mech.Engrs70,onflat and round test specimens having partially circular 627–632[Bull.Jpn Soc.Mech.Engrs11,14–23].notches under various loading conditions.In:Boundary Elements 8H.Nisitani and N.A.Noda(1984)Stress concentration of aXII(Edited by M.T anaka,C.A.Brebbia and T.Honma), cylindrical bar with a V-Shaped circumferential groove under Computational Mechanics Publications,Southampton,Boston, torsion,tension or bending.Engng Fracture Mech.20(5/6),pp.327–342.743–766.©1999Blackwell Science Ltd.Fatigue Fract Engng Mater Struct22,1071–1082。
压力限制肿瘤增长翻译 中英
最后译文：压力限制肿瘤生长法国物理学家发现了简单的力压在医学上可应用于降低肿瘤的生长速度并限制其生长大小。
通过使用老鼠细胞来完成这项工作的研究者说这个结果可以引生出更好的癌症诊断工具并很可能最终实现用药物治疗癌症。
众所周知当生长细胞中的DNA发生突变时就会形成肿瘤并发展为癌症, .但是这种发展是如何受到肿瘤周围环境的影响仍是一个需要讨论的课题。
由巴黎居里学院的让.弗朗斯科乔尼和其他一些院校进行了一项新的调查，研究肿瘤的生长是如何受到它所经受的压力的限制的，如同按压周围的健康组织一样。
很难把基因学、生物化学和力学在生物机体内的肿瘤中所扮演的角色分离出来。
为了解释这一问题，乔尼的团队用老鼠细胞中的一个直径十余毫米的类似肿瘤的球在实验台上进行了这项工作，工作者们把这个模拟肿瘤放入一个由半渗透聚合物制成的几毫米长的袋子中，这之后就进入到一个滋生细胞的包含营养物的研究方案中。
肿瘤在这种自由的状态下会继续生长两周或者三周, 直到达到细胞的死亡和分裂刚好平衡的稳态。
糖分的严厉打击为了找出在这个生长过程中是什么影响到了压力, 小组在此方案中加入了很多糖分这些糖分由于颗粒太大而无法穿过袋子的微小孔洞所以仍在袋子外面，造成了一种浓度的不平衡，而使其迫切的要解决掉袋子外的溶液以努力恢复其浓度的平衡，袋子外较大浓度的溶液随即对袋子产生了力度的压迫，并且这种压迫被里面的肿瘤所感应到。
这种方法被重复用于同样的肿瘤上，每个不同袋子中的肿瘤被不同浓度的糖分溶液所浸透，因此揭示出每个肿瘤都受到了不同的压力。
该小组发现压力越大，肿瘤生长越慢并且最终尺寸越小。
比如施加500帕的压力，仅仅百分之两点五的气压），便可将肿瘤的增长率和稳态量减半。
为了精准地确立压力是如何减弱增长的，乔恩和他的同事将肿瘤冰冻起来，将其切成非常薄的薄片，.并在薄片上覆盖两种抗体，这个方法显示出了在每个肿瘤上已死亡而被分离的细胞----这两种细胞发出的荧光波长不同-。
醌鞣化作用 英语
醌鞣化作用英语Quinone Tanning ReactionIntroductionThe quinone tanning reaction is an important chemical process used in the production of leather goods. It involves the conversion of protein collagen into a stable, insoluble form, making the leather durable and resistant to decay. This article aims to explore the principles behind the quinone tanning reaction, the chemical reactions involved, and its significance in the leather industry.1. The Mechanism of Quinone TanningThe quinone tanning reaction is a two-step process that occurs when a quinone compound reacts with the protein collagen in the presence of an oxidizing agent. The first step involves the formation of a Schiff's base, which is a reversible reaction between the quinone and the primary amine groups of the collagen. This results in the formation of a quinone-imine complex.The second step is the oxidation of the quinone-imine complex to form a stable cross-linking structure within the collagen matrix. The oxidizing agent plays a crucial role in this step by providing the necessary electron transfer to facilitate the cross-linking reaction. The resulting chemically modified collagen is insoluble and resistant to biological degradation, thus creating a durable material suitable for leather production.2. Chemical Reactions InvolvedThe quinone tanning reaction involves several key chemical reactions. The primary step is the reaction between the quinone compound and the primary amine groups of the collagen. This reaction forms a Schiff's base, which is further oxidized to yield a stable cross-linked structure.The oxidizing agent commonly used in the quinone tanning process is a metal salt, such as chromium sulfate or aluminum sulfate. These metal salts act as electron acceptors, facilitating the oxidation and cross-linking reactions. Other compounds, such as formaldehyde, can also be used as oxidizing agents in specific tanning processes.3. Significance in the Leather IndustryThe quinone tanning reaction revolutionized the leather industry by providing a more efficient and effective method of tanning compared to traditional methods. Previously, tanning relied on animal-derived tannins, which were costly and limited in availability. Additionally, traditional tanning methods required longer processing times and resulted in a less durable final product.The introduction of quinone tanning allowed for faster processing times and improved leather quality. The resulting leather products exhibited enhanced durability, resistance to water, and resistance to microbial attack. This led to the rapid adoption of quinone tanning in the leather industry, making it the dominant tanning method used today.ConclusionThe quinone tanning reaction is a vital process in the leather industry, enabling the production of high-quality, durable leather goods. Through aseries of chemical reactions, the quinone compound reacts with collagen to form a stable cross-linked structure. This results in leather that is resistant to decay, water, and microbial attacks. The significance of quinone tanning cannot be overstated, as it has revolutionized the leather industry, providing a more efficient and cost-effective method of tanning.。
翻译原件
Prediction of fatigue failure in a camshaft using the crackmodelling methodG.Wang a,*,D.Taylor a ,B.Bouquin a ,J.Devlukia b ,A.Ciepalowicz baDepartment of Mechanical Engineering,Trinity College,Dublin,IrelandbRover Group,Gaydon Test Centre,Warwick,UKReceived 30April 1999;accepted 26June 1999AbstractCamshafts made of grey cast iron and used in Rover vehicles were tested under cyclic bending and torsion and modelled using FE.A new technique known as crack modelling was used to predict the fatigue limit.The method uses a linear elastic ®nite element analysis to derive an equivalent stress intensity factor (K )for stress concentrations in components.K is calculated without introducing a crack into the component:the stress ®eld around the maximum stress point is examined and compared to that for a standard centre-cracked plate.This component was a challenge for the technique because it involved a blunt notch and local surface e ects.Fatigue limits were successfully predicted for two di erent designs and two loading modes,but some inaccuracies remain which suggest modi®cations to the theory.#2000Elsevier Science Ltd.All rights reserved.Keywords:Fatigue limit;Stress concentrations;Finite element analysis;Surface layers;Cast iron1.IntroductionFatigue failure in components usually initiates at stress concentrations:geometric features such as holes,grooves and corners,and despite some local plasticity,high-cycle fatigue behaviour is essentially a linear±elastic problem.Traditional methods show poor accuracy when applied to high-gradient stress concentrations (e.g.sharp notches and small notches)and to materials of low notch-sensitivity (e.g.cast irons).The crack modelling approach deals with this problem by modelling the notch as a crack.This allows the calculation of an equivalent stress-intensity factor (K ),enabling standard fracture mechanicsEngineering Failure Analysis 7(2000)189±1971350-6307/00/$-see front matter #2000Elsevier Science Ltd.All rights reserved.PII:S 1350-6307(99)00015-1/locate/engfailanal*Corresponding author.Tel.:+353-1-6081976;fax:+353-1-6795554.E-mail address:wangg@tcd.ie (G.Wang).methodology to be used.Fatigue is assumed to occur if the cyclic value of K exceeds the crack propagation threshold.Previous papers [1,2]have reported the application of this method to components of complex geometry,which were subjected to bending and,recently [3],torsion.The present paper considers a component which presented two challenges for the method.Firstly,failure occurred from a relatively blunt notch,whose stress-concentration factor,K t ,was approximately 2,so it was not clear whether this type of notch could be usefully modelled using fracture mechanics;secondly,the as-cast component was known to have a hard surface layer which appeared to improve its fatigue strength.It was therefore necessary to extend the crack modelling method to include this e ect.2.Experimental detailsTables 1and 2show the material properties and composition of the material,which was a typical grey cast iron.The threshold stress intensity factor at R =À1was found previously [4]to be D K th =15.94MPa m 1/2.Fig.1shows a general view of the camshaft component,which contained a number of geometric features.The component was clamped at one end as shown,and loaded either in bending or torsion (both at R =À1),to produce failure at a chosen location,as shown in the detail in Fig.1.Two designs were tested:the ®rst had an as-cast notch,1mm deep,1.5mm root radius;in the second design,machining was used to remove the cast surface,deepening the notch to 1.75with 1.63mm root radius.The K t factors for these notches were 2.1in bending (for both notch depths)and 1.6for the as-cast notch in torsion.The S/N data for the material was obtained using standard hourglass specimens loaded in axial tension/compression at R =À1.Vickers hardness was measured using macro-and micro-indents,to record its variation as a function of distance from the surface.3.ResultsFigs.2±4show test results in the form of Wohler curves,plotting applied load range for the component tested in bending (Fig.2),torque range for the torsion testing (Fig.3)and stress range for the plain specimens (Fig.4).The material fatigue limit,de®ned at 107cycles,was 190MPa.The resultsTable 1Mechanical properties of grey cast iron Young's modulus 170GPaPoisson's ratio 0.29Yield stress202MPa (s 0.2)Ultimate strength249MPaTable 2Composition of grey cast iron (%weight)C S Mn Si Ni Cu P Cr 3.30.091.51.80.070.20.030.05G.Wang et al./Engineering Failure Analysis 7(2000)189±197190showed a degree of scatter which is typical for this material,giving variations on the load (or stress)axis of 10±20%from the mean.Fig.5shows hardness results;it is clear that,despite some scatter,the micro-indent hardness of the as-cast component was higher near the surface,especially within 1mm,whereas this was not the case for the machined component or for the macro-indent hardness readings.The average Vickers-hardness on the as-cast surface was 395.5.The average value in the bulk was 326.6.This di erence appeared to arise due to a change in the amount and morphology of the cementite phase;it was thus detected bytheFig.1.Camshaft component,showing loading and detail of the notch which causedfailure.Fig.2.Camshaft bending test results:(a)as-cast notch;(b)machined notch.G.Wang et al./Engineering Failure Analysis 7(2000)189±197191micro-indents,which were always placed in the matrix (pearlite/cementite)and not in the graphite nodules.The average value for the machined condition was 319.3,which is not signi®cantly di erent from the as-cast bulkvalue.Fig.3.Camshaft torsion test results (as-castcondition).Fig.4.Plain specimen bar tension/compression test results.G.Wang et al./Engineering Failure Analysis 7(2000)189±1971924.Finite element analysisANSYS software was used to create a ®nite element model;a quarter model was used (Fig.6)because the component is axially symmetrical apart from the cam lobes which do no carry much stress.The bending and torsion loading was treated as a symmetrical or asymmetrical load,respectively.The models were meshed using 3-D parabolic tetrahedral elements.Element size close to the notch was about 0.75mm.A linear elastic analysis was used.In each case the highest stress occurred at the notch tip.Fig.7shows the ®rst principal stress plotted as a function of distance,r ,measured from the notch tip alongaFig.5.Vickers-hardness of camshaft:(1)micro hardness on the machined surface;(2)macro hardness on the machine surface;(3)micro hardness on the as-cast surface;(4)macro hardness on the as-castsurface.Fig.6.The ®nite element model,showing in detail the mesh around the notch tip.The arrow shows the line on which the stress±distance curve was measured.G.Wang et al./Engineering Failure Analysis 7(2000)189±197193straight line drawn in the direction perpendicular to the ®rst principal stress direction at the tip (see Fig.6).The loading in each case corresponds to the experimental fatigue limit of the component.5.Prediction of fatigue limit 5.1.The crack modelling methodThe crack modelling method has been described in detail elsewhere [1,2,5].It is based on the Westergaard equation which gives the stress-distance (s ±r )function for a crack of length a w in tension at a stress s w in an in®nite plate:s s w a 1À a w a a w r 2 1a 2X1The values of s w and a w in Eq.(1)can be varied to obtain a best ®t with the s ±r curve taken from a component (as in Fig.7).Then the appropriate K value is given by:K s wp a w p X 2 This method assumes that if the equivalent stress intensity range,D K ,found by applying Eq.(2),is lessthan the threshold value of the material,fatigue failure will not occur.A post-processor was written in Visual Basic to interface with ANSYS software,allowing the value of K to be calculated automatically.Previous publications [2,3,5]have discussed the choice of direction on which to measure the s ±r curve and the start and end points of the curve.Table 3shows predictions of the fatigue limit of the component (expressed in terms of applied load range);here the crack modelling method is compared with predictions made simply by using the maximum stress at the notch (i.e.the hot-spot stress).It is clear that the use of maximum stress underestimates the performance of the component considerably.It is possible to modify this hot-spot prediction by using empirical factors which depend on root radius (e.g.Peterson [6])or on local stress gradient (e.g.Siebel and Stieler [7]).Such factors are commonly used in industry but are unreliable because they are highly material-dependent and not mechanistically based.Another commonly used method is the `local-strain approach'in which performance is based on notch-root plastic strain.This also gives improved predictions but requires a lot of specialised material data such as cyclic stress±strain curves and elastic±plastic FEA.The crack modelling method is advocated instead of the above methods because it requires relatively little data and a simple elastic FE analysis,and because it is groundedinFig.7.FEA results:s ±r curves for each case at the experimental fatigue limit.G.Wang et al./Engineering Failure Analysis 7(2000)189±197194the well-known methods of fracture mechanics.In this case the crack modelling prediction was an improvement over the maximum-stress prediction in all three cases,but signi®cant errors remained,especially for the as-cast case in bending.Table 4shows a revised prediction in which a correction factor was introduced to allow for the surface e ect noted above.This correction was made by using the methodology of Murakami and Endo [8,9],who proposed a generalised method for the analysis of small surface defects and notches.They proposed that,for steels,the fatigue limit could be predicted by assuming that the notch was a crack:the size parameter they used was `area'Ðde®ned as the area of the defect projected normal to the stress axis.They proposed equations for the fatigue limit and threshold for notches in all steels,as follows:D s 1X 43 H v 120area p À1a 6, 3D K th 3X 3Ã10À3 H v 120area p 1a 3X4Here H v is the Vickers micro-hardness.Since in a case such as the present one where the notch geometry is kept constant and the hardness changes,both the threshold and the fatigue limit should increase in proportion to (H v +120)which,given the hardness values quoted above,implies an increase of a factor of 1.15for the as-cast case.This increase applies to the maximum-stress method as well as to the crack-modelling method.Table 3Prediction of fatigue limit:without considering the surface e ect LoadExp.dataPrediction using maximum stress Crack modelling prediction Ds max (MPa)D P Error %D K max (MPa m 1/2)D P Error %Bending a (kN) 1.50408.000.70À53.4313.10 1.8321.68Bending b (kN) 3.10672.000.88À71.7323.40 2.11À31.88Torsion a (Nm)510360.00269.17À47.2216.20501.81À1.60a Camshaft with machined surface.bCamshaft in as-cast form.Table 4Prediction of fatigue limit:including the surface e ect LoadExp.dataPrediction using maximum stress Crack modelling prediction D s max (MPa)D P Error %D K (MPa m 1/2)D P Error %Bending a (kN) 1.50408.000.70À53.4313.10 1.8321.68Bending b (kN) 3.10672.00 1.01À67.4923.40 2.43À21.66Torsion b (Nm)510360.00309.54À39.3116.20577.0913.15a Camshaft with machined surface.bCamshaft in as-cast form.G.Wang et al./Engineering Failure Analysis 7(2000)189±1971956.DiscussionAs Table 4shows,this method,along with the correction for surface hardness,has the e ect of bringing all the predictions to within about 20%of the experimental values.This is quite satisfactory,since one would expect errors of at least 10%in the experimental results,the FE analysis and the basic material data.However,it is interesting to note that the prediction for torsion loading is relatively non-conservative,whereas that for bending (as-cast)is conservative.This implies that the method overestimates the fatigue strength in torsion,and this problem is one which merits further investigation.This analysis has also demonstrated that,in some cases,the crack-modelling method can be applied to very blunt notches.Previous papers [5,10]discussed the range of validity of the method:following Smith and Miller [11]it is assumed that this fracture-mechanics approach will be valid for relatively sharp notches,with the maximum-stress method being valid for blunter ones.However,for a material such as cast iron,which has a particularly low notch-sensitivity,the crack-modelling method will have a greater range of validity,being preferred for many of the stress concentrations which are found on components.7.Conclusions1.The crack-modelling method,which predicts fatigue limits of stress concentrations using a fracture-mechanics approach,was able to predict the behaviour of an automotive camshaft component in two di erent design cases under both bending and torsion loading.2.Failure occurred from a very blunt notch (K t =1.6±2.1)but even so the crack-modelling method gave better predictions than a method using the maximum notch-root stress.This implies that the method is suitable for a very wide range of features in materials of low notch-sensitivity,such as this grey cast iron.3.A simple method based on hardness measurements was successful in allowing for the existence of a hardened surface layer.This provides some support for the approach of Murakami and Endo.AcknowledgementsThe authors are grateful to Enterprise Ireland and Materials Ireland for funding provided to one of the authors (G.Wang).References[1]Taylor D.Crack modelling:a technique for the fatigue design of components.Engineering Failure Analysis 1996;3(2):129±36.[2]Taylor D,Ciepalowicz AJ,Rogers P,Devlukia J.Prediction of fatigue failure in a crankshaft using the technique of crackmodelling.Fatigue Fract Engng Mater Struct 1997;20(1):13±21.[3]Taylor D,Zhou W,Ciepalowicz AJ,Devlukia J,Mixed-mode fatigue from stress concentrations:an approach based onequivalent stress intensity,Int J Fatigue 1999;21:173±8(in press).[4]Taylor D,Hughes M,Allen D.Notch fatigue behaviour in cast irons explained using a fracture mechanics approach.Int JFatigue 1996;18(7):439±45.[5]Taylor D,Lawless S.Prediction of fatigue behaviour in stress-concentrators of arbitrary geometry.Eng Fract Mechanics1996;53:929±39.[6]Peterson S.Notch sensitivity.In:Sines G,Waisman JL,editors.Metal fatigue.New York:McGraw-Hill,1959.p.293±306.G.Wang et al./Engineering Failure Analysis 7(2000)189±197196G.Wang et al./Engineering Failure Analysis7(2000)189±197197[7]Siebel E,Stieler M.Dissimilar stress distributions and cyclic loading.Z Ver Deutsch Ing1955;97:121±31.[8]Murakami Y,Endo M.E ects of hardness and crack geometries on D K th of small cracks emanating from small defects.J SocMater Sci Japan1986;35(395):911±7.[9]Murakami Y,Kodama S,Konuma S.Quantitative evaluation of defects of non-metallic inclusions on fatigue strength of highstrength steels.Int Journal of Fatigue1989;11:291±8.[10]Taylor D,O'Donnell M.Notch geometry e ects in fatigue:a conservative design approach.Engineering Failure Analysis1994;1:275±87.[11]Smith RA,Miller KJ.Prediction of fatigue regimes in notched components.Int J Mech Sci1978;20:201±6.。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
2. Specimen Design
Figure 1 summarizes various cantilever bend specimens that have been used to evaluate fracture and fatigue of carburized steels over the past 35 years. 17-13] The Brugger design, shown in Fig. l(a), was developed to evaluate toughness and fatigue of carburized steel. The Brugger specimen design was altered by other investigators to accommodate machining considerations and fatigue testing machine capability. DePaul [9] defines three requirements for Brugger-type cantilever bend specimens: (1) an abrupt change in cross section to act as aBiblioteka 1. Introduction
A recent review of the bending fatigue performance of carburized steel identified a wide range of reported fatigue limits.Ill The variations in fatigue behavior may not only reflect differences in processing history and microstructure, but also differe n c e s in specimen geometry. Coarse carbide particles and excessive retained austenite at the square edges of carburized cantilever bend specimens have been shown to serve as preferred sites for fatigue crack initiation. [2,3[ This information was developed in a study of SAE 8620 and EX24 steels vacuum carburized at 1050 ~ (1920 ~ The high carbon level introduced into austenite at 1050 ~ could not be effectively lowered at the square specimen edges during the diffusion portion of the carburizing cycle. As a result, undesirable microstructures developed and served as fatigue crack initiation sites, thus reducing bending fatigue performance. To provide a better assessment of the effects of alloying, processing, and microstructure on fatigue of carburized steel, several studies subsequent to that of Jones and Krauss [2,3l have used cantilever bend specimens with rounded edges. [4,5] The rounded edges develop a uniform case depth after carburizing and eliminate at least one cause of the variations observed in measuring bending fatigue performance. Another approach to avoiding undesirable comer microstructures has been to copper plate square-edged bending fatigue specimens before final grinding of the tension surface. [6[ The copper plating on the side surfaces prevents excessive carbon concentration at corners, resulting in a uniform case alongthe line of maximum stress. Although Jones and Krauss [2,3]reported the undesirable microstmctures developed in square-edged specimens, their work was not designed to examine specimen geometry effects, and no comparison with round-edged specimens was performed. The subsequent work of Erven and Pacheco 14,5]investigated alloying and processing influences on bending fatigue performance with round-edged specimens to eliminate the detrimental
R.E. Cohen, D.K. Matlock, and G. Krauss, Advanced Steel Proc-
corner effect, but no direct comparison was made between square and round-edged specimens. In addition, carburizing at a lower temperature than used by Jones and Krauss, around 930 ~ (1700 ~ a temperature typically used for gas carburizing, may reduce the potential carbon saturation of austenite during the initial boost stage of carburizing and, therefore, may not cause the excessive carbon retention noted by Jones and Krauss. The purpose of the present study is to measure the influence of specimen geometry on the bending fatigue of carburized steel, with a comparison of two sets of SAE 4320 steel specimens. Both sets of specimens, one with square edges and one with round edges, were identically carburized at the same time at 927 ~ (1700 ~ The information developed in this study provides an estimate of the extent to which specimen geometry affects microstructure and fatigue of conventionally carburized steel. This influence of geometry may be useful for the evaluation of specimen designs for the study of bending fatigue in case-hardened steel and may serve as a guide when interpreting results, given the wide range of reported bending fatigue limits. Specimen geometry has been recognized as an influence on bending fatigue performance. Three-point bend, four-point bend, cantilever beam, and rotating beam specimens have been used to evaluate fatigue of carburized steel. Variations in specimen geometry exist because of differences in starting material, machining capability, and testing machine configuration and capacity. The next section briefly reviews the various types of cantilever specimens that have been used to evaluate bending fatigue of carburized steel.