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 -
439 views
Technical Discussions
John Brunk
Engineering, NDT Level III
Self employed, part-time, USA, Joined Oct 1999, 162

John Brunk

Engineering, NDT Level III
Self employed, part-time,
USA,
Joined Oct 1999
162
05:55 Oct-11-2000
temperature effects on plastic wedges

When performing angle beam testing of metals, there is a change in beam angle with temperature. This happens because the velocity change in plastic wedge materials for a given temperature change is larger than the change in the metal.
Beam angle increases with increasing temperature. The effect is most likely to be noticed when testing at high temperatures with a 70 degree wedge. Surface waves can drive you crazy. It has to be almost too cold to work to get
longitudinal waves with a 45 degree wedge. The more common problem is to be wrong about the location of the reflector because of the change in beam angle. I don't have the data with me and won't trust my memory for the numbers; but
I wrote an article about this for Materials Evaluation about 1987. I noticed this problem a couple of years earlier working outside in Wyoming in the winter. Different plastics used for wedges have different temperature coefficients.
If you keep your angle beam calibration reference at the same temperature as the test object, and keep track of the actual angle and attenuation as the temperature changes, that should take care of most problems unless you really have
to have a specific beam angle for a good reason. Attenuation changes can also be due to effects on the couplants.


 
 Reply 
 
William Friedman
R & D,
Lockheed Martin, USA, Joined Nov 1998, 6

William Friedman

R & D,
Lockheed Martin,
USA,
Joined Nov 1998
6
05:12 Oct-12-2000
Re: temperature effects on plastic wedges
: When performing angle beam testing of metals, there is a change in beam angle with temperature. This happens because the velocity change in plastic wedge materials for a given temperature change is larger than the change in the metal.
:
The problem I described in attenuation change occurs just as much when angle beams are not used so I don't think we are seeing an effect that occurs because of a change in angle. The difficulty is that even with a straight beam you might undercall the size of a flaw due when the temperature of the acrylic holder used to couple the transducer to the part.

William Friedman


 
 Reply 
 

Product Spotlight

ISONIC 3510

Very Powerful Superior Performance Extremely Portable Smart Phased Array Ultrasonic Flaw Detector an
...
d Recorder with 2 Conventional UT and TOFD Channels uniquely combines PA, single- and multi-channel conventional UT, and TOFD modalities providing 100% raw data recording and imaging. Suitable for all kinds of every-day ultrasonic inspections
>

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.
>

FAAST-PA! OEM Patented phased Array for high speed UT inspection

Multiangle, Multifocus, Multifrequency, Multibeam. Instead of stacking UT electronics and having m
...
any PA probes, FAAST-PA is able to transmit all delay laws within ONE single shot in Real time.
>

A1525 SOLO

A1525 Solo – the most compact and affordable TMF unit with two phased array transducers and 3D v
...
isualization and analysis software in standard delivery set. A compact, ergonomic and easy to handheld Phased Array unit based on Total Focusing Method for easy-going imaging of inspection objects with two-dimensional and three-dimensional visualization and evaluation of inspection results.
>

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