Ultrasonic Test to be done under prelimities.pptx

ultrsonic

1. UNIT IV ULTRASONIC TESTING AND ACOUSTIC EMISSION TESTING

2. Introduction of Ultrasonic Testing Ultrasonic system uses high frequency sound energy to conduct examinations and identify surface discontinuities. Ultrasonic examinations can be conducted on a wide variety of material forms including castings, forgings, welds, and composites . Because of high penetration capacity, extremely high thickness sections inspection is possible.

3. Introduction of Ultrasonic Testing Ultrasonic wave are sound waves, basically vibrations of the particles in a solid, liquid or gas. One cycle of vibration/sec is represented as frequency. Unit is hertz. Sound wave having frequency above 20000 Hz(20 kHz) are called ultrasonic waves. Most UT carried out frequency between 5,00,000 and 1,00,00,000 cycles per seconds(500 kHz to 10 MHz)

4. Introduction of Ultrasonic Testing At frequency in MHz range, sound energy does not travel efficiently through air/other gases. But it travel freely in liquid and common engineering materials. Sound wave will travel through given medium at specific speed Sound wave having frequency above 20000 Hz(20 kHz) are called ultrasonic waves. Most UT carried out frequency between 5,00,000 and 1,00,00,000 cycles per seconds(500 kHz to 10 MHz)

5. Introduction of Ultrasonic Testing The sound wave will travel through a given medium at specific speed, in a predictable direction. They will be reflected or transmitted according to the rules. This principles is adopted in ultrasonic flaw detection.

6. Frequency range of sound waves

7. Mode of wave Propagation

8. Mode of wave Propagation Also known as Raleigh waves, represent oscillating motion that travels along the surface of test piece to a depth of one wavelength

9. Lamp wave

10. Basic Principle of Ultrasonic testing

11. Basic Principle of Ultrasonic testing Sound waves with high frequencies(20 kHz) are called ultrasonic waves, are used to detect the presence of flaws/defects in internal structure of the metal. Consists of Pulser /receiver, Transducer and display unit Driven by pulser, the transducer generate high frequency ultrasonic energy. This sound energy is introduce and propagates through the metal in the form of waves.

12. Basic Principle of Ultrasonic testing When there is a crack in the wave path, part energy will be reflected back from the flaw surface. The reflected wave signal is transformed into an electrical signal by the transducer and is displayed on the screen. From the signal the information about the defect location, size orientation and other features can be identified

13. Advantages of UT Advantages Small discontinuities can be detected Portable device with instant test result Thickness and length upto 10 meters can be tested. High sensitivity, greater accuracy Non hazardous operation High temperature testing possible Min no. Of Consumables

14. Limitations of UT Limitations Surface must be accessible to transmit ultrasound Rough and uneven surface acn reduce the effectiveness of the test. Coupling medium is necessary to promote the transfer of sound energy in to the specimen Require high skilled and trained persons No permanent record is possible.

15. Ultrasonic Testing methods 1.Transmission method Two transducer used T transducer-Used to transmit the sound wave R transducer-Used to receive the sound wave The test piece is without defect, the signal received by receiver transducer is relatively large. If there is flaw, then the signal received by transducer will be reduced.

16. 1.Transmission method

17. Pulse echo method

18. Pulse echo method 2.Pulse echo method Only one transducer is used which act as a both transmitter and receiver. Consists of Frequency generator, Display unit(CRO),Transducer and amplifier. Couplant is used to separate the test object from the transducer. If there is a crack in the wave path, the part of energy is reflected back from the flaw (crack) surface. The reflected wave signal is transformed into electrical signal by receiver transducer and is displayed in the screen. From the signal information about the flaw location , size and orientation can be identified.

19. Equipment for Ultrasonic testing 1.Pulser/receiver 2.Ultrasonic transducer 3.Couplant 4.Display 5.Receiver/Amplifier

20. Ultrasonic Equipment

21. Equipment for Ultrasonic testing 1 .Pulser/receiver A short burst of alternating electrical energy is called as pulse. This circuit generate the high voltage pulse The Ultrasonic wave are produced by large amplitude electric pulses. This circuit also act as a receiver of signal from transducer. 2.Ultrasoni Transducer(Search unit) Pulsed and sending out an ultrasonic wave.

22. Equipment for Ultrasonic testing 3.Couplant Used to reduce the air gap between the transducer and surface of the test piece. A very thin air will severely retard the transmission of sound waves from the transducer to the material. 4.Display/Oscilloscope Used to display the received data/signal ,either in video mode or radio frequency mode. 5.Receiver /Amplifier The voltage signal received by receiver from ultrasonic transducer are amplified. The amplified radio frequency are available as output display on oscilloscope

23. Sequence operations in UT Clock and pulser provide short, high voltage pulse to the transducer while simultaneously supplying the voltage to the time base trigger module. The voltage pulse reaches the transducer and converted in to mechanical vibrations which enter into the test piece. The energy in the test piece now reflect back toward the transducer, where it is converted in to voltage. This voltage is now received and amplified by receiver amplifier. This cycles of events is continued to detect the flaws in the test piece.

24. Transducers Transfer electrical energy to mechanical energy and vice versa. Also called Probes, Search units, test heads The ultrasonic transducers used to generate and detect ultrasonic waves. Piezo electric elements are in UT purpose because it is capable of generating complete range of ultrasonic frequencies.

25. Piezo Electric Transducer

26. Selection factor Factors considered in selection of Transducer Material factor Geometry and surface condition Frequency(500 kHz-20 MHz) Sensitivity Bandwidth Wave form duration

27. Types of Transducer Based on Construction principle Involved Piezo Electric transducer Polyvinylidene fluoride transducer Electro magnetic Acoustic transducer(EMAT) Laser generated ultrasound

28. Piezo Electric Transducer

29. Electro magnetic Acoustic transducer(EMAT)

30. Types of Transducer 2. Based on applications Contact Dual element Angle beam Delay line Protected face Immersion High frequency Phased array transducers

31. Contact Transducer 1. Contact Transducer-A contact transducer is a single element longitudinal wave transducer intended for use in direct contact with a test piece. Provide high frequency

32. Dual element transducers 2. Dual element Transducer- Dual element transducers contain two independently operated elements in a single housing. One of the elements transmits and the other receives the ultrasonic signal. very useful when making thickness measurements

33. Angle beam Transducer 3.Angle beam- Angle beam allows the inspection where there cannot be accesses by ultrasonic path The angled sound path allows the sound beam to be reflected from the back wall to improve detect ability of flaws in and around welded areas. They are also used to generate surface waves for use in detecting defects on the surface of a component .

34. Delay Line Transducer The primary function of a delay line transducer is to introduce a time delay between the generation of the sound wave and the arrival of any reflected waves. This allows the transducer to complete its "sending" function before it starts its "listening" function so that near surface resolution is improved. They are designed for use in applications such as high precision thickness gauging of thin materials and delaminating checks in composite materials and high temperature application

35. Protected Face Transducers Single element longitudinal wave transducer with threaded case sleeves which allow a dely line through wear cap/membrane Versatile and wide range of application Pliable polymeric membrane used to assist coupling to rough or uneven surface

36. Immersion Transducer

37. High Frequency Transducer 7.High Frequency Transducer Either delay line or Focusing type Range 20 MHz to 225 MHz thin Silicon based composites materials

38. Phased Array Transducer Phased Array Transducer- A series of single element transducers arranged in such a manner to increase inspection coverage area. Circular or rectangular pattern

39. Focused transducer 9. Focused Transducer- The sound energy can be focused so that it concentrate the energy at a particular depth /area within the test piece. can improve the sensitivity and axial resolution

40. Wheel Transducer 10. Wheel Transducer - Transducer are located in a holders with sealed wheel that have been filled with fluid. Very useful for examination of moving components.

41. Ultrasonic Inspection technique Straight beam ultrasonic inspection method Angle beam ultrasonic inspection method Time of flight diffraction(TOFD) Phased array ultrasonic inspection method Immersion ultrasonic inspection method

42. Straight beam ultrasonic inspection method

43. Angle Beam Inspection

44. Time of flight diffraction(TOFD) technique

45. Phased Array Ultrasonic testing

46. Immersion Ultrasonic Technique

47. Data presentation Data presentation in Ultrasonic Testing A-scan presentation B- scan presentation C- scan presentation

48. A-scan presentation

49. B-scan presentation

50. C-scan presentation

51. Variables influencing the Results in Ultrasonic testing Variables influencing the Results Temperature Attenuation Frequency and grain size Surface conditions Diameter changes Contact pressure and couplant

52. Application of Ultrasonic Testing Testing welds in pressure vessels, pipes, structures, bridges, aircraft and marines, etc Ferrous and Non-ferrous pipes, rod and bars Large castings, Forgings Detecting corrosion in various petroleum and gas supply lines Blow holes, Porosity, grain size

53. A-scan display in welded joint

54. Thickness Measurement

55. Inspection of Aircraft Casting

56. Inspection of Aircraft Casting

57. Corroded pipe wall thickness

58. Composite materials with defect location