1、過(guò)程裝備與控制工程專(zhuān)業(yè)Words and Expressionscontenttranslationexercisesexamples書(shū)本介紹作者介紹Process Equipment &Control EngineeringSpecialized English XXXXXXXXXXXXXXXXXX過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Words and Expressions 1. oscillatory siltri a.振蕩的，擺動(dòng)的 2. confront knfrnt v.面臨，面對(duì)(be confronted with) 3. wearw v. ; n.磨損，損耗，耐磨(性)

2、 4. fatigue f ti: n. v.(使)疲勞;fatigue failure疲勞破壞(失效) 5. acute kju:t a.敏銳的，尖銳的過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Words and Expressions 6. impair imp vt.;n.損害傷)，減少(弱) 7. symmetrical simetrikl a.對(duì)稱(chēng)的，勻稱(chēng)的 8. propeller prupel n.螺旋槳，推進(jìn)器 9. compact kmpkt, kmpkt v.壓實(shí)，夯實(shí);a.壓緊的 10. chaff t:f, tf n.谷殼，廢物，渣滓過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Words

3、 and Expressions 11. thresh(=thrash) re v.猛烈擺動(dòng)，顛簸 12. glider laid n滑翔機(jī) 13. panel pnl n.底板，座，儀表板 14. helical helikl n.;a.螺旋(線，面，形)(的) 15. springboard sprib:d n跳板，出發(fā)點(diǎn)過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Words and Expressions 16. pendulum pendjulm n.擺(錘)，振動(dòng)體 17. bob bb n.振子球，秤錘 18. displacement displeismnt n.位移，平移，移動(dòng)(度) 1

4、9. customary kst,mri n.通常的，(合乎)習(xí)慣的 20. reciprocal risiprkl a.相互的，倒數(shù)的;，.倒數(shù)，互逆過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Words and Expressions 21. amplitudemplitju:d n.振幅，擺幅，幅度 22. angularjul adj.角(形，狀)的，成角度的 23. dissipative disipeitiv a.損耗的，消耗(性)的 24. damp dmp v.阻尼，減振，弄濕 25. viscous visks adj.粘性的，粘滯的過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Words and

5、 Expressions 26. constrain knstrein vt.約束，束縛，強(qiáng)制 27. coordinate ku:dinit, ku:dineit n坐標(biāo)(系);a.坐標(biāo)的，同位的 28. specify spesfai vt.指定，確定，詳細(xì)說(shuō)明過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations A mechanical vibration is an oscillatory，periodically repeated motion of a particle or body about a position of equilibri

6、um .An engineer is frequently confronted with the problem of machinery and structures.original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 機(jī)械振動(dòng)是質(zhì)點(diǎn)或物體在其平衡位置附近所作的震蕩的，周期性的往復(fù)運(yùn)動(dòng)。 工程師經(jīng)常面臨機(jī)械振動(dòng)的問(wèn)題，因?yàn)樵谀撤N程度上他們?cè)趲缀跛械臋C(jī)械和結(jié)構(gòu)中遇到過(guò)這些問(wèn)題translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations Most vibrations

7、 are undesirable in machines and structures because they produce excessive stresses or repeated stresses;original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 大多數(shù)的震動(dòng)在機(jī)械和結(jié)構(gòu)中是不希望存在的，因?yàn)檎饎?dòng)會(huì)產(chǎn)生附加應(yīng)力或者交變應(yīng)力。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations cause added wear;increase bearing lo

8、ads; induce fatigue;create acute passenger discomfort in planes，ships，trains，buses，and automobiles;and absorb energy that could otherwise do useful work.original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 引起額外磨損，增大軸承載荷，導(dǎo)致疲勞破壞，使飛機(jī)、船、火車(chē)及汽車(chē)上的乘客產(chǎn)生嚴(yán)重的不舒服感，并且振動(dòng)會(huì)吸收本可以做有用功的能量。translated text過(guò)程裝備與控制工程

9、專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations The collapse of the Tacoma Narrows Bridge in 1940 is an example of structural failure due to excessive stresses produced by vibrations. The accuracy of precision instruments，tools，and machines may be impaired by excessive vibrations. original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單

10、元Unit 5 Mechanical Vibrations 1940年（發(fā)生的）塔克馬窄橋的垮塌事件就是一個(gè)因?yàn)檎饎?dòng)產(chǎn)生的附加應(yīng)力導(dǎo)致結(jié)構(gòu)失效的例子。 精密儀器、工具和電腦的準(zhǔn)確性可能被附加的震動(dòng)所損壞 translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations Rotating machine parts require careful balancing in order to prevent damage from vibrationoriginal text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical

11、 Vibrations 旋轉(zhuǎn)機(jī)械零件需要仔細(xì)的平衡,以防止振動(dòng)的造成的傷害。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations When part of the propeller of an airplane is shot off or breaks off in flight the propeller is no longer symmetrical，and the vibrations from the engine may tear the engine from the plane unless it can

12、be stopped in time.original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 當(dāng)飛機(jī)的螺旋槳的（某）部分在飛行中被打掉或斷裂，（這時(shí)）螺旋槳不再是對(duì)稱(chēng)的，來(lái)自引擎的振動(dòng)會(huì)把引擎從飛機(jī)上扯下來(lái),除非它可以被及時(shí)的停止。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations The vibrations produced in an automobile by the engine or by driving on rough roads set up r

13、epeated stresses in certain parts that can eventually lead to fatigue failure of the members.original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 由引擎產(chǎn)生的震動(dòng)或由于在崎嶇的道路上行駛產(chǎn)生的震動(dòng)施加在某部分的交變應(yīng)力最終會(huì)使其發(fā)生疲勞失效translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations When a particle or body that is supporte

14、d by a system of springs，a shaf t，a beam，or any other elastic system is disturbed from its position of equilibrium by the application and sudden removal of an additional force the particle or body will vibrate. original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 當(dāng)被彈簧，桿，線或者其他彈性系統(tǒng)支撐的質(zhì)點(diǎn)或物體，在被干擾或

15、者受到外力的作用使其偏離平衡位置，質(zhì)點(diǎn)或物體就會(huì)發(fā)生震動(dòng)。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations Some common example are the vertical vibratory motion of body A in Fig.1.19.(a) when it is displaced vertically from its equilibrium position on a helical spring and then released ; original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5

16、單元Unit 5 Mechanical Vibrationstranslated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations the vertical vibratory motion of body B of Fig.1.19.(b) when it is displaced from its equilibrium position on a flexible springboard (cantilever beam) of negligible mass and released;original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)

17、第5單元Unit 5 Mechanical Vibrationstranslated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations and the motion of the pendulum bob C in Fig.1.19.(c) as it swings in a vertical plane when supported by a cord of negligible massoriginal text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrationstranslated text過(guò)程裝備與

18、控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations Fig .1 .20(a)shows a body W suspended from a support by a spring and hanging at its equilibrium position. If the body is pulled from its equilibrium position by a force F and released，it will，in the absence of any frictional forces，continue to oscillate about

19、 the equilibrium position indefinitely .original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 圖1.20 a中所示的物體W，懸掛彈簧上，處于平衡位置。當(dāng)它在力F的作用下拉離平衡位置時(shí)被釋放，在沒(méi)有摩擦阻力時(shí)，它將在平衡位置附近做連續(xù)性不斷地?cái)[動(dòng)。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations Fig.1.20 (b)shows a graph of the displacement，y，of the body W fr

20、om its equilibrium position as a function of time . One of the fundamental properties of mechanical vibrations is that the motion repeats itself at definite interval of time . The period ,T ,of the oscillation is the minimum amount of elapsed time before the motion starts to repeat itself . The moti

21、on completed in one period cycle . original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 圖1.20b 中所示為物體W偏離平衡位置的距離y對(duì)時(shí)間的圖像。機(jī)械振動(dòng)的基本內(nèi)容之一就是在一段時(shí)間內(nèi)的重復(fù)運(yùn)動(dòng)。震動(dòng)的周期，T，是它開(kāi)始重復(fù)運(yùn)動(dòng)之前，運(yùn)動(dòng)時(shí)間的最小值。運(yùn)動(dòng)在一個(gè)周期內(nèi)完成。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations The frequency，f，of the oscillation is the number o

22、f cycles which occur in a given unit of time ;the customary unit is cycles per second，cps，or hertz，Hz，It should be noted that the frequency is the reciprocal of the period，or，in equation form，f=1/Toriginal text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 震動(dòng)的頻率，f，是單位時(shí)間內(nèi)所做的循環(huán)的次數(shù)。常用的單位是周期/秒，cps，赫茲，hz。

23、值得注意的是，頻率和周期是互相聯(lián)系的或者說(shuō)，用一個(gè)方程式f=1/T。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations The amplitude，A，of the oscillation is the maximum displacement，either linear or angular，of the body from its equilibrium position.original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 震動(dòng)的振幅，A，是距其平衡位置（

24、震動(dòng)的）最大位移，不管是直線運(yùn)動(dòng)還是擺動(dòng)。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations Mechanical vibrations which are maintained by elastic，and sometimes gravity，forces are called free vibrations. Once started，a free vibration，frequently called a natural vibration，continues to oscillate at its natural f

25、requency. original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 被松緊帶保持的機(jī)械振動(dòng)，有時(shí)同時(shí)在重力，及其他力的作用下被稱(chēng)作自由振動(dòng)。一旦開(kāi)始，自由振動(dòng)經(jīng)常被稱(chēng)作固有振動(dòng)，連續(xù)的以它的固有頻率擺動(dòng)。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations A forced vibration is produced and maintained by a periodic exciting force external to the system，and

26、it takes place at the frequency of the exciting force.If the system is nearly frictionless and contains no dissipative elements，the amplitude of the forced oscillation will become very large when the frequency of the exciting force is close to the natural frequency of the system.original text過(guò)程裝備與控制

27、工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 受迫振動(dòng)是振動(dòng)系統(tǒng)在周期性的外力作用下產(chǎn)生并保持的，并以外力的頻率運(yùn)動(dòng)。如果系統(tǒng)是無(wú)摩擦的而且不包含任何能量損失，在驅(qū)動(dòng)力的頻率接近固有頻率的時(shí)候是，受迫振動(dòng)的振幅會(huì)變得越來(lái)越大。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations Thus, although the frequency of a forced vibration is independent of the natural frequency of the elastic syst

28、em，the resulting amplitude is affected by both frequencies. Vibrations are also classified as damped or undamped . When friction，air resistance，viscous damping，and all other resisting forces are negligible the vibration is undamped. original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 因此，盡管受迫振

29、動(dòng)的頻率和彈性系統(tǒng)的固有頻率無(wú)關(guān)，但是產(chǎn)生的振幅卻受這兩個(gè)頻率的影響。振動(dòng)也可以分類(lèi)為阻尼振蕩和無(wú)阻尼振蕩。當(dāng)摩擦力，空氣阻力，粘滯阻力，及其他阻力可忽略時(shí)，這時(shí)的振動(dòng)式無(wú)阻尼振動(dòng)。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations When any of these effects is appreciable the body has damped vibrations. In practice there is always a frictional damping force which will eventuall

30、y stop a free vibration，even though it may be neglected for many purposes.original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 當(dāng)這些阻力中的任何一個(gè)不可忽略時(shí)，物體做阻尼振動(dòng)。實(shí)際上，總有由摩擦力產(chǎn)生的阻尼力最終使自由振動(dòng)停止，即使這個(gè)力可以因某種目的被忽略。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations If the motion of a particle or body is

31、constrained so that its position can be completely specified by one coordinate,it is said to have a single degree of freedom. original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 如果質(zhì)點(diǎn)或物體的運(yùn)動(dòng)是被約束的，以至于它的位置完全可以用一個(gè)坐標(biāo)表示，被稱(chēng)為具有單一的自由度。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations If the

32、system can vibrate in two direction or is composed of two articles that can each vibrate independently in one direction, it is said to have two degrees of freedom because two coordinates are required to specify the position of the system at any instant. original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanica

33、l Vibrations 如果系統(tǒng)可以在兩個(gè)方向振動(dòng)，或者由可分別在一個(gè)方向上單獨(dú)振動(dòng)的兩個(gè)運(yùn)動(dòng)組成的，則被成為有兩個(gè)自由度，因?yàn)槿我鈺r(shí)刻的系統(tǒng)位置需要兩個(gè)坐標(biāo)指定。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations For example, a system composed by a spring as indicated in Fig.1.21(a), which vibrated in a vertical direction only, has one degree of freedom. original text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations 例如，如圖1.21(a)中，由一個(gè)彈簧組成的只在垂直方向上震動(dòng)的系統(tǒng)，有一個(gè)自由度。translated text過(guò)程裝備與控制工程專(zhuān)業(yè)英語(yǔ)第5單元Unit 5 Mechanical Vibrations A system composed of two particles which move ve