1、襄樊學院畢業(yè)設計(論文)英文翻譯題 目超聲波簡介及其應用專 業(yè)機械設計制造及其自動化班 級機制0712姓 名劉康學 號07116201指導教師職 稱李梅副教授2011年5月25日Introduction and application of ultrasonicUltrasonic is a mechanical waves which frequency above 20,000 Hz. Ultrasonic inspection commonly used in the frequency of 0. 55 MHz. The mechanical waves in the material

2、 spread in a certain speed and directions, acoustic impedance different heterogeneous interfaces such as defect is encountered or the bottom surface of the object being tested, will reflections. This reflection phenomenon can be used to ultrasonic testing , most common is pulse echo testing method t

3、esting , pulse oscillator issued of voltage plus in probe with pressure electric ceramic or quartz chip made of detection components , probe issued of ultrasonic pulse by sound coupled media such as oil or water , entered material and in which spread , encountered defects , part reflection energy al

4、ong original way returns probe , probe will change it in electric pulse , by instrument zoom and display in oscilloscope tubes of screen . Depending on where the flaw echo on the screen and amplitude of reflection wave with artificial defects in a reference block rate compared to defect location and

5、 approximate dimensions. Apart from Echo method, and use another probe to the other side of the workpiece to accept signal penetration method. When use ultrasonic detection the physical properties of materials, also often take advantage of ultrasonic in sound velocity, attenuation and resonance char

6、acteristics of workpiece.Ultrasonic characteristics: 1, ultrasonic beam to focus on a specific direction, along the straight lines in the media, has a good point. 2, ultrasonic wave propagation in the media, attenuation and scattering occurs. 3, ultrasonic wave on the interface of heterogeneous medi

7、a will make reflection, refraction and mode conversion. Using these features, you can get the defective interface from reflected reflection, so as to achieve the purpose of detecting defects. 4, ultrasonic energy is power than sonic. 5, the ultrasonic loss is very small in solid transmission , probe

8、 depth, as occurs in the hetero - interface by ultrasonic phenomena such as reflection, refraction, especially not by gas - solid interface. If the metal air holes, flaws and layer defects such as defects in a gas or a mixture, when defects at the interface of ultrasonic propagation to the metal and

9、 on all or part of the reflection. Reflected ultrasonic probe received, handled through circuits inside the instrument, on the screen of the instrument will show a different height and have a certain pitch waveform.Based on waveform characteristics of determine defect depth, location, and shape of t

10、he workpiece.Non - destructive testing is not damaged parts or raw materials subject to the status of the work, a means of detection of surface and internal quality checks, Nondestructive Testing abbreviations short for NDT. Ultrasonic testing is also called ultrasonic, ultrasonic flaw detector, is

11、a type of non - destructive testing. UT is on industrial ultrasonic testing non - destructive testing methods. Ultrasonic enters objects when a defect is encountered, some sound waves produce reflection, transmit and receive an analysis of the reflected wave, exception can accurately gauge the flaws

12、. And is able to display the location and size of internal defects, determination of material thickness.Advantages of ultrasonic inspection is to detect thickness, high sensitivity, high speed, low cost, is harmless to human body, can be positioned and quantitative defects. Display of ultrasonic det

13、ection on defects are not intuitive, testing of technical difficulty, vulnerable to subjective and objective factors, and inspection results are not easy to hold, ultrasonic testing requirements on the work surface smooth, requiring experienced inspectors to identify defects types, suitable for the

14、part of considerable thickness inspection, ultrasonic inspection has its limitations.Variety of ultrasonic flaw detector, but most widely application of pulse - echo ultrasonic flaw detector. In general, in uniform material, presence of defect will create material discontinuity, this often acoustic

15、impedance of the discontinuity is inconsistent , by the reflection theorem we know that, in two different acoustic impedance by ultrasonic reflection on the interface of media occurs. Size and interface on both sides of the reflected energy media differences in acoustic impedance and orientation, re

16、lative to the size of the interface. Pulse - echo ultrasonic flaw detector is designed according to this principle. Most of pulse - echo ultrasonic flaw detector is a scan, the so-called A-scan display is the way the display of ultrasonic detection in materials is the horizontal coordinate of transm

17、ission time or distance, the ordinate is the amplitude of ultrasonic reflected wave. Such as , in a workpiece in the exists a defects , because defects of exists , between defects and material formed a different media junction surface, interface of sound impedance different , when launch of ultrason

18、ic encountered this interface will occurs reflection , reflection back of energy and probe received it, in monitor screen in the horizontal of must of location on will display out a reflection wave of waveform , horizontal of this location is defects wave in was detection material in the of depth .

19、The reflected wave height and shape of different because of different defects, reflecting the nature of the defectNow is usually on the measured object, human launch industrial materials such as ultrasound, and then use its reflection, Doppler effect, transmission to get the formation of internal in

20、formation and processing of measured object image. Ultrasonic flaw detector which more general Doppler effect method is using ultrasonic in encountered movement of object Shi occurs of more general Doppler frequency moved effect to came the object of movement direction and speed , characteristics ;

21、transmission rule is by analysis ultrasonic penetrating had was measuring object of changes and came object of internal characteristics of , its application currently also is development stage ; ultrasonic flaw detector here main describes of is currently application up to of by reflection method to

22、 gets object internal characteristics information of method. Reflection method is based on ultrasonic in by different sound impedance organization interface will occurs strong reflection of principle work of , as we all know , When sonic from a media spread to another media in the interface will occ

23、urs reflection , and media of differences more large reflection will more large , so we can launch out penetrating force strong , and to line spread of ultrasonic to a object , and on reflection back of ultrasonic for received and under these reflection back of ultrasonic , and range , situation on

24、can judgment out this organization in the contains of various media of size , and distribution situation and various media of comparison differences degree , information which reflection back of ultrasonic of has can reflect out reflection interface away from detection surface of distance , range ca

25、n reflect out media of size , and comparison differences degree , characteristics , ultrasonic flaw detector to judgment out the was measuring object is has exception . In this process involves many aspects of content, including produce, receive, ultrasonic signal conversion and processing. One meth

26、od is through the circuit of ultrasonic excitation signals to crystals such as quartz, lithium sulfate, with the piezoelectric effect, making it resulting in ultrasonic vibration ; receives the reflected ultrasonic waves when the piezoelectric crystals, there will be pressure from the reflected soun

27、d waves and electrical signals and transferred to the signal processing circuit for a series of processing, observation of ultrasonic flaw detector resulting images for people to judge.Types of image processing can be divided into A type display display, M and B type show, C-type display, such as F-

28、type display. Which A type display is will received to of ultrasonic signal processing into waveform image , under waveform of shape can see was measuring object inside is has exception and defects in there , and has more large , ultrasonic flaw detector main for industrial detection ; M type displa

29、y is will a section after fai of processing of detection information by time order expand formation a dimension of space more points movement timing figure , for observation internal is movement state of object , ultrasonic flaw detector as movement of organ , and artery vascular; B type display is

30、will side - by - side many section after fai of processing of detection information group synthesis of second dimension of , and reflect out was measuring object internal fault section of Anatomy image hospital in using of B Super is with this principle do out of , ultrasonic flaw detector for obser

31、vation internal is static of object ; and c type display , and F type display now with was comparison less . Detection of ultrasonic flaw detector can be very accurate, and more convenient, fast compared to other testing methods, nor harmful to detect objects and actions, so welcomed by the people m

32、ore and more popular, has a very broad prospects for development. With the further development of electronic technology and software technology, digital ultrasonic flaw detector there are broad development prospects. Believe in the near future, more advanced new generation of digital intelligent ult

33、rasonic flaw detector will gradually replace traditional analog detector, mainly for image display detector will be widely used in industrial inspection.Ultrasonic characterization of defects is always a difficult problem, still mainly relies on experience and analysis of inspection personnel, and p

34、oor accuracy. Development of the modern discipline of artificial intelligence for the realization of instrument automatic defect characterization offers the potential. Application of pattern recognition technology and expert systems, various characteristics of a large number of known defects input s

35、ample library, to accept the equipment people experience, and after studying with automatic defect characterization capabilities.超聲波簡介及其應用超聲波是頻率高于20千赫的機械波。在超聲探傷中常用的頻率為0.55兆赫。這種機械波在材料中能以一定的速度和方向傳播，遇到聲阻抗不同的異質(zhì)界面（如缺陷或被測物件的底面等）就會產(chǎn)生反射。這種反射現(xiàn)象可被用來進行超聲波探傷，最常用的是脈沖回波探傷法探傷，脈沖振蕩器發(fā)出的電壓加在探頭上（用壓電陶瓷或石英晶片制成的探測元件），探頭發(fā)

36、出的超聲波脈沖通過聲耦合介質(zhì)（如機油或水等）進入材料并在其中傳播，遇到缺陷后，部分反射能量沿原途徑返回探頭，探頭又將其轉(zhuǎn)變?yōu)殡娒}沖，經(jīng)儀器放大而顯示在示波管的熒光屏上。根據(jù)缺陷反射波在熒光屏上的位置和幅度（與參考塊中人工缺陷的反射波幅度作比較），即可測定缺陷的位置和大致尺寸。除回波法外，還有用另一探頭在工件另一側(cè)接受信號的穿透法。利用超聲法檢測材料的物理特性時，還經(jīng)常利用超聲波在工件中的聲速、衰減和共振等特性。超聲波的特點：1、超聲波聲束能集中在特定的方向上，在介質(zhì)中沿直線傳播，具有良好的指向性。2、超聲波在介質(zhì)中傳播過程中，會發(fā)生衰減和散射。3、超聲波在異種介質(zhì)的界面上將產(chǎn)生反射、折射和波型

37、轉(zhuǎn)換。利用這些特性，可以獲得從缺陷界面反射回來的反射波，從而達到探測缺陷的目的。4、超聲波的能量比聲波大得多。5、超聲波在固體中的傳輸損失很小，探測深度大，由于超聲波在異質(zhì)界面上會發(fā)生反射、折射等現(xiàn)象，尤其是不能通過氣體固體界面。如果金屬中有氣孔、裂紋、分層等缺陷（缺陷中有氣體）或夾雜，超聲波傳播到金屬與缺陷的界面處時，就會全部或部分反射。反射回來的超聲波被探頭接收，通過儀器內(nèi)部的電路處理，在儀器的熒光屏上就會顯示出不同高度和有一定間距的波形?？梢愿鶕?jù)波形的變化特征判斷缺陷在工件中的深度、位置和形狀。無損檢測是在不損壞工件或原材料工作狀態(tài)的前提下，對被檢驗工件的表面和內(nèi)部質(zhì)量進行檢查的一種檢測

38、手段，Nondestructive Testing（縮寫NDT）。超聲波檢測也叫超聲檢測、超聲波探傷，是無損檢測的一種。 超聲檢測(UT）是工業(yè)上無損檢測的方法之一。超聲波進入物體遇到缺陷時，一部分聲波會產(chǎn)生反射，發(fā)射和接收器可對反射波進行分析，就能異常精確地測出缺陷來并且能顯示內(nèi)部缺陷的位置和大小，測定材料厚度等. 超聲波探傷優(yōu)點是檢測厚度大、靈敏度高、速度快、成本低、對人體無害，能對缺陷進行定位和定量。超聲波探傷對缺陷的顯示不直觀，探傷技術(shù)難度大，容易受到主客觀因素影響，以及探傷結(jié)果不便于保存，超聲波檢測對工作表面要求平滑，要求富有經(jīng)驗的檢驗人員才能辨別缺陷種類、適合于厚度較大的零件檢驗，

39、使超聲波探傷也具有其局限性。 超聲波探傷儀的種類繁多，但脈沖反射式超聲波探傷儀應用最廣。一般在均勻材料中，缺陷的存在將造成材料不連續(xù)，這種不連續(xù)往往造成聲阻抗的不一致，由反射定理我們知道，超聲波在兩種不同聲阻抗的介質(zhì)的界面上會發(fā)生反射。反射回來的能量的大小與交界面兩邊介質(zhì)聲阻抗的差異和交界面的取向、大小有關。脈沖反射式超聲波探傷儀就是根據(jù)這個原理設計的。 脈沖反射式超聲波探傷儀大部分都是A掃描式的，所謂A掃描顯示方式即顯示器的橫坐標是超聲波在被檢測材料中的傳播時間或者傳播距離，縱坐標是超聲波反射波的幅值。譬如，在一個工件中存在一個缺陷，由于缺陷的存在，造成了缺陷和材料之間形成了一個不同介質(zhì)之間的交界面，交界面之間的聲阻抗不同，當發(fā)射的超聲波遇到這個界面之后就會發(fā)生反射，反射回來的能量又被探頭接收到，在顯示器屏幕中橫坐標的一定的位置就會顯示出來一個反射波的波形，橫坐標的這個位置就是缺陷波在被檢測材料中的深度。這個反射波的高度和形狀因