where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

Sonotron NDT
Original developer and manufacturer of advanced ultrasonic instruments
6172 views
Technical Discussions
RT JEYAKUMAR
NDT Inspector
Singapore, Joined Aug 2002, 10

RT JEYAKUMAR

NDT Inspector
Singapore,
Joined Aug 2002
10
06:15 May-24-2005
SENSITIVITY in UT

As we know sensitivity in UT is half of wavelength., and we know wavelength is v/f., that means, if velosity decreases in the material., will sensitivity increases

Case 1. So, I can put in this way, sensitivity will increase to lower velosity material and decrease for higher velosity material.

Case2. So, sensitivity in shear wave probe is higher than longitudinal wave probe.

Can anyone please kindly explain this confusion.


 
 Reply 
 
N.Kuppusamy
Consultant, Level-III
United Testing Co. Pte Ltd, Singapore, Joined Jan 2003, 13

N.Kuppusamy

Consultant, Level-III
United Testing Co. Pte Ltd,
Singapore,
Joined Jan 2003
13
04:52 May-25-2005
Re: SENSITIVITY in UT
Hi,

You are correct. For a given frequency, the sensitivity increases as the velocity decreases for the same size of reflector.

The reflectivity of the defect also plays an important role in the defect detection. Reflectivity is the amount of energy reflected by the defect. Generally it is different for different material.

For a given material, the sensitivity increases as velocity decreases, thus the highest sensitivity is achieved by the surface waves followed by shear waves and compressional waves.

Hope this would clear your doubts.

N.Kuppusamy

----------- Start Original Message -----------
: As we know sensitivity in UT is half of wavelength., and we know wavelength is v/f., that means, if velosity decreases in the material., will sensitivity increases
: Case 1. So, I can put in this way, sensitivity will increase to lower velosity material and decrease for higher velosity material.
: Case2. So, sensitivity in shear wave probe is higher than longitudinal wave probe.
: Can anyoneplease kindly explain this confusion.
------------ End Original Message ------------




 
 Reply 
 
Paul A. Meyer
R & D,
GE Inspection Technologies, USA, Joined Nov 1998, 47

Paul A. Meyer

R & D,
GE Inspection Technologies,
USA,
Joined Nov 1998
47
06:57 May-25-2005
Re: SENSITIVITY in UT
Hello,
To continue from the previous response, a reflector has directivity. For a given material wavelength, the reflected sound becomes more directional as the reflector size increases. Similarly, for a given reflector size, the reflected sound becomes more directional as the wavelength decreases. Look at the directivity equations for UT transducers and you will notice directivity is a function of d/lambda (size/wavelength). The directivity of a reflector is identical, except the wavelength is that of the incident sound field.
Paul


----------- Start Original Message -----------
: Hi,
: You are correct. For a given frequency, the sensitivity increases as the velocity decreases for the same size of reflector.
: The reflectivity of the defect also plays an important role in the defect detection. Reflectivity is the amount of energy reflected by the defect. Generally it is different for different material.
: For a given material, the sensitivity increases as velocity decreases, thus the highest sensitivity is achieved by the surface waves followed by shear waves and compressional waves.
: Hope this would clear your doubts.
: N.Kuppusamy
: : As we know sensitivity in UT is half of wavelength., and we know wavelength is v/f., that means, if velosity decreases in the material., will sensitivity increases
: : Case 1. So, I can put in this way, sensitivity will increase to lower velosity material and decrease for higher velosity material.
: : Case2. So, sensitivity in shear wave probe is higher than longitudinal wave probe.
: : Can anyone please kindly explain this confusion.
------------ End Original Message ------------




 
 Reply 
 
N.Kuppusamy
Consultant, Level-III
United Testing Co. Pte Ltd, Singapore, Joined Jan 2003, 13

N.Kuppusamy

Consultant, Level-III
United Testing Co. Pte Ltd,
Singapore,
Joined Jan 2003
13
01:12 May-26-2005
Re: SENSITIVITY in UT
Hi,

I approached this problem from the theoritical point of view by keeping all other variables constant except wavelength.

The reflectivity also includes the acoustic impedance mismatch difference.

Regards,
N.Kuppusamy
----------- Start Original Message -----------
: Hello,
: To continue from the previous response, a reflector has directivity. For a given material wavelength, the reflected sound becomes more directional as the reflector size increases. Similarly, for a given reflector size, the reflected sound becomes more directional as the wavelength decreases. Look at the directivity equations for UT transducers and you will notice directivity is a function of d/lambda (size/wavelength). The directivity of a reflector is identical, except the wavelength is that of the incident sound field.
: Paul
:
: : Hi,
: : You are correct. For a given frequency, the sensitivity increases as the velocity decreases for the same size of reflector.
: : The reflectivity of the defect also plays an important role in the defect detection. Reflectivity is the amount of energy reflected by the defect. Generally it is different for different material.
: : For a given material, the sensitivity increases as velocity decreases, thus the highest sensitivity is achieved by the surface waves followed by shear waves and compressional waves.
: : Hope this would clear your doubts.
: : N.Kuppusamy
: : : As we know sensitivity in UT is half of wavelength., and we know wavelength is v/f., that means, if velosity decreases in the material., will sensitivity increases
: : : Case 1. So, I can put in this way, sensitivity will increase to lower velosity material and decrease for higher velosity material.
: : : Case2. So, sensitivity in shear wave probe is higher than longitudinal wave probe.
: : : Can anyone please kindly explain this confusion.
------------ End Original Message ------------




 
 Reply 
 
S.V.Swamy
Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 787

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
787
09:40 May-26-2005
Re: SENSITIVITY in UT
----------- Start Original Message -----------
: As we know sensitivity in UT is half of wavelength., and we know wavelength is v/f., that means, if velosity decreases in the material., will sensitivity increases
: Case 1. So, I can put in this way, sensitivity will increase to lower velosity material and decrease for higher velosity material.
: Case2. So, sensitivity in shear wave probe is higher than longitudinal wave probe.
: Can anyone please kindly explain this confusion.
------------ End Original Message ------------

Dear Jeyakumar,

There is no confusion. Both of your statements are correct in themselves. Thus, for the same type of waves, i.e. longitudinal, the sensitivity will be better in a material with a lower velocity and thus a shorter wavelength for a given frequency.

For a given material, for a given frequency, shear wave mode of testing will have higher sensitivity since the wavelength of shear waves will be roughly half the longitudinal wavelength.

And combining boththe cases, it is true that for a material with lesser velocity, shear wave mode of testing (assuming that the shear wave velocity is a constant fraction of the longitudinal wave velocity, an assumption not strictly valid), will give higher sensitivity than for a material with higher velocity and tested in longitudinal mode.

As can be seen, there is no confusion.

Best regards,

Swamy





 
 Reply 
 
Philippe Rubbers
Engineering
SCM, South Africa, Joined Nov 1998, 22

Philippe Rubbers

Engineering
SCM,
South Africa,
Joined Nov 1998
22
09:18 May-27-2005
Re: SENSITIVITY in UT
Dear Sir

Shear waves are much more sensitive for corner reflectors than long waves, (for equal wavelengths), due to the energy conversion efficiencies, (diffraction and reflection coefficients). An excellent reference book would be:
Krautkramer J. Krautkramer.H Ultrasonic testing of materials. 1968 Ed. George Allen andUnwin.
Tables and curves for these coefficients are found in the appendix.

But your paradox is definitively a point to ponder.

Best regards

----------- Start Original Message -----------
: Hi,
: I approached this problem from the theoritical point of view by keeping all other variables constant except wavelength.
: The reflectivity also includes the acoustic impedance mismatch difference.
: Regards,
: N.Kuppusamy
: : Hello,
: : To continue from the previous response, a reflector has directivity. For a given material wavelength, the reflected sound becomes more directional as the reflector size increases. Similarly, for a given reflector size, the reflected sound becomes more directional as the wavelength decreases. Look at the directivity equations for UT transducers and you will notice directivity is a function of d/lambda (size/wavelength). The directivity of a reflector is identical, except the wavelength is that of the incident sound field.
: : Paul
: :
: : : Hi,
: : : You are correct. For a given frequency, the sensitivity increases as the velocity decreases for the same size of reflector.
: : : The reflectivity of the defect also plays an important role in the defect detection. Reflectivity is the amount of energy reflected by the defect. Generally it is different for different material.
: : : For a given material, the sensitivity increases as velocity decreases, thus the highest sensitivity is achieved by the surface waves followed by shear waves and compressional waves.
: : : Hope this would clear your doubts.
: : : N.Kuppusamy
: : : : As we know sensitivity in UT is half of wavelength., and we know wavelength is v/f., that means, if velosity decreases in the material., will sensitivity increases
: : : : Case 1. So, I can put in this way, sensitivity will increase to lower velosity material and decrease for higher velosity material.
: : : : Case2. So, sensitivity in shear wave probe is higher than longitudinal wave probe.
: : : : Can anyone please kindly explain this confusion.
------------ End Original Message ------------




 
 Reply 
 

Product Spotlight

Magnetic X-Ray Pipeline Crawler

Zhong Yi brand pipeline crawler is magnetic/micro-video controlled crawler with DC X ray unit inst
...
alled for checking welding of pipeline. Move steadily inside the pipeline 6''-60''diameter with speed of up to 18m/min, Max. moving diatance 5 kilometers and provide the efficient inspection of the pipeline.
>

SONOAIR - air-coupled Phased Array Ultrasonic Inspection System

For highly attenuating materials, the performance of the system is critical. The ultrasonic sensors,
...
the scanning area and the system settings should be flexibly adapted to the test task and the material. These high expectations are met with the new and modular testing system SONOAIR. With the world’s first air-coupled phased-array UT inspection system SONOAIR we developed a technology that works with up to 4 transmitter and receiver channels with freely configurable square wave burst transmitters as wells as low noise receiving amplifiers.
>

iProbe - USB Phased Array Probe

Turn your PC, Laptop or Tablet into a powerful 32:64 Phased Array system with our USB powered Phas
...
ed Array iProbe and inspection software package. Perform affordable weld inspection and corrosion mapping inspections with this powerful but small system. The probe has a 100V pulser, 8K PRF, dual axis encoder input and achieves outstanding signal quality.
>

FD800 Bench Top Flaw Detectors

The bench-top FD800 flaw detector range combines state-of-the-art flaw detection with advanced mater
...
ial thickness capabilities. Designed for use in the laboratory these gauges are the tool you need for all your flaw detecting needs.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window