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 -

808 views
Technical Discussions
Lirin Philip
,
VALDEL , India, Joined Sep 2019, 10

Lirin Philip

,
VALDEL ,
India,
Joined Sep 2019
10
06:34 Sep-09-2019
How to select Rectifier in Ultrasonic testing.

Selection of Rectifier in ultrasonic testing ,like full wave,half wave positive ,half waves negatives or radio frequency ,what is criteria selection of that mainly doing operation on carbon composite material. We are using Omni scan sx by olympus.

 
 Reply 
 
nick bublitz
Other,
VeriPhase, USA, Joined May 2010, 137

nick bublitz

Other,
VeriPhase,
USA,
Joined May 2010
137
15:04 Sep-09-2019
Re: How to select Rectifier in Ultrasonic testing.
In Reply to Lirin Philip at 06:34 Sep-09-2019 (Opening).

Generically-
Full wave for angle beam flaw detection where maximum echo response is of most importance. RF to visualize phase shift- bond testing etc. Half wave for thickness testing/corrosion testing.
You can search for and apply conventional ut principles on these displays to phased array.

from Olympus tutorial on UT:
Received echoes can be displayed either as an unrectified RF signal, as half wave positive or half wave negative rectified signals, or with full wave rectification. Raw echoes are initially processed as RF waveforms with both positive and negative peaks. The RF display mode is useful when working with very thin test pieces and in cases where echo phase or polarity is of interest. Half wave positive rectification shows only the positive peaks, while half wave negative rectification shows only the negative peaks, flipped to the positive side of the baseline. Half wave rectification can in some cases improve signal-to-noise by reducing spurious peaks. Full wave rectification displays both positive and negative echo lobes together on the positive side of the baseline and is the most commonly used format in flaw detection applications

3
 
 Reply 
 
Paul Holloway
Consultant,
Holloway NDT & Engineering Inc , Canada, Joined Apr 2010, 255

Paul Holloway

Consultant,
Holloway NDT & Engineering Inc ,
Canada,
Joined Apr 2010
255
15:18 Sep-09-2019
Re: How to select Rectifier in Ultrasonic testing.
In Reply to Lirin Philip at 06:34 Sep-09-2019 (Opening).

zoom image



Further to Nick's comments, half-wave is best used in thickness testing to ensure that measurements are always made on wave lobes of the same polarity.

If you use full wave rectification, it is impossible to tell whether your gate is triggering on a positive or negative lobe (see attached image). This may be inconsequential if your measurement resolution requirements are relatively low (i.e. if you don't care about the nearest 0.005" or 0.010", then full wave may be fine!).

But if you are doing very fine, precise work (e.g. pen probe or small diameter high frequency dually) then you are definitely better off using half wave.

Use RF mode to start, find out which wave lobe is the best, then calibrate off that and go for it.
2
 
 Reply 
 
Lirin Philip
,
VALDEL , India, Joined Sep 2019, 10

Lirin Philip

,
VALDEL ,
India,
Joined Sep 2019
10
10:17 Sep-10-2019
Re: How to select Rectifier in Ultrasonic testing.
In Reply to Paul Holloway at 15:18 Sep-09-2019 .

I'm working in the field of composite materials and the maximum thickness of composite parts comes around less than 5mm.

 
 Reply 
 

Product Spotlight

Sci Aps Z-Series Portable Handheld Analysers

The world’s only handheld analyzer that measures carbon content in stainless (yes even L-grades),s
...
teels, and cast irons. Also accepted for low Si analysis for sulfidic corrosion analysis, and is widely used in the power industry for Cr analysis, for flow accelerated corrosion applications.
>

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.
>

TESTD-PT SYSTEM

Pulse thermography is a non-contact test method that is ideal for the characterization of thin fil
...
ms and coatings or the detection of defects. With a remarquable short test time and a high detection sensitivity, the Telops TESTD-PT is the perfect tool for non- destructive testing. With such high frame rates, it is even possible to investigate highly conductive or diffusive materials.
>

Robotic laser shearography enables 100% inspection of complex, flight-critical composite structures

An article in “Composites World Magazine” showcases Non Destructive Testing of aero-structures
...
with Laser Shearography. Over the years Dantec Dynamics has supplied many solutions for the aerospace industry. Referring to specific customer projects several of these cases are examined to outline the advantages of using Laser Shearography for automated defect detection.
>

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