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 -

1660 views
Technical Discussions
Faisal
R & D,
Universiti Tun Huseein Onn Malaysia, Malaysia, Joined Feb 2014, 4

Faisal

R & D,
Universiti Tun Huseein Onn Malaysia,
Malaysia,
Joined Feb 2014
4
12:00 Jul-03-2015
How to determine material velocity and time of flight of hand lay-up Glass Fiber Composite Laminate (GFCL) material?

Hi all..

I'm sorry if my question quite typical and poor grammar.. I'm really appreciate if someone can help me regarding this subject.

Currently, I did some UT on my specimen that is glass fiber composite laminates (7.4mm is about 24 plies) to determine inclusion/delam defect signal. I'm using 2.25MHz single crystal immersion transducer together with UT350 Ultratek pulse-receiver. The output was spectrum A-scan signal. As advised by supplier, the material velocity was set 2740m/s.. I saw GFCL material velocity setup is around 2500-2700 m/s..

my question is:-

1) Is it possible for me to perform some experimental setup to get specific material velocity for that
particular material & how?

2) How do I confirm that my inspection system goes well? I mean how to calibrate the transducer?

3) Is there any trick/procedure to get time domain signal instead of spectrum A-scan signal for my further UT signal understanding?

again.. TQVM for those interested to reply my question.. :)

 
 Reply 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
22:36 Jul-06-2015
Re: How to determine material velocity and time of flight of hand lay-up Glass Fiber Composite Laminate (GFCL) material?
In Reply to Faisal at 12:00 Jul-03-2015 (Opening).

Hello, Faisal --

Do not worry about your writing... it is very clear! I will offer a couple suggestions, although I afraid that I am not familiar with the Ultratek instrument that you are using. Also, I do not know exactly what type of transducer you are using. Hopefully it is a broadband design. A frequency of 2.25 MHz for 7.4 mm glass fiber composite is a good starting point.

1. In general, velocity measurement in immersion mode involves measuring the pulse transit time between two echoes, the one from the front surface of the test piece and the one from the back wall. The front surface echo should be obvious. If the back wall echo is not also obvious because of noise, try rubbing your finger on the back side of the wet test piece and look for the echo that dampens when you touch the back surface. That will be the back wall echo. If your instrument offers bandpass filtering, use a ~2 MHz filter to help clean up noise. If you do not see any back wall echo at all, then your transducer is probably not optimum for the test material.

Once you have identified the echoes from the front and back surface, measure the time interval between them. That is the round trip transit time in the test piece. To obtain the velocity, divide that number by two to get the one-way transit time, then divide the thickness of the test piece by the the one-way transit time to get the velocity.

2. The accuracy of your system will depend on the accuracy of the time base of your instrument and to some extent also on the degree of echo distortion (if any) caused by your material. You might practice the technique with something that will produce a very clean signal, like a flat piece of high density polyethylene (typical velocity for HDPE is approximately 2460 m/s) or polystyrene (typical velocity 2340 m/s) of roughly the same thickness as your test piece.

3. You will have to consult the manufacturer of your pulser/receiver for this answer, or perhaps another Ultratek user will respond. All of the pulser/receivers that my company makes provide a simple time domain A-scan signal (RF waveform) as a standard output, and I expect that the Ultratek instrument can do that as well. It's probably just a matter of instrument setup.

Good luck!

 
 Reply 
 
Faisal
R & D,
Universiti Tun Huseein Onn Malaysia, Malaysia, Joined Feb 2014, 4

Faisal

R & D,
Universiti Tun Huseein Onn Malaysia,
Malaysia,
Joined Feb 2014
4
09:01 Jul-08-2015
Re: How to determine material velocity and time of flight of hand lay-up Glass Fiber Composite Laminate (GFCL) material?
In Reply to Tom Nelligan at 22:36 Jul-06-2015 .

Hi Tom Nelligan,

Thank you for your valuable advice. Here I enclosed several image + user manual regarding my UT inspection process using us ultratek pulse-receiver for further info.. (image 1) to (image 4) is during UT setup, (image 5) is A-scan signal and (image 6) is my GFCL sample.

(image 1) https://copy.com/2asPqhJgFthR6a1S
(image 2) https://copy.com/nDalikguiGIjqENL
(image 3) https://copy.com/UkvKSatKh6Ln6B4k
(image 4) https://copy.com/euGeBjxWMAOKhItE
(image 5) https://copy.com/cLlcCpL27qsZ1YQj
(image 6) https://copy.com/dSCZkRt2uWrihxGL

(user manual) http://www.scribd.com/doc/223479102/USB-UT350UsersGuide#scribd

As your advice in #1, I think I already obtained front wall and back wall signal (refer image 5).. but in this GUI already show in (mm) unit. So, how to measure the time interval between them?

As your advice for calibration in #2, if I'm using polystyrene but almost third times thicker (~20mm) than my GFCL sample (7.4mm), can I simply just devide into 3 for the final result? (because it hard for me to find polystyrene <20mm)

 
 Reply 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
15:27 Jul-08-2015
Re: How to determine material velocity and time of flight of hand lay-up Glass Fiber Composite Laminate (GFCL) material?
In Reply to Faisal at 09:01 Jul-08-2015 .

Faisal --

Sorry, but you will have to consult Ultratek for instructions on how to set up your instrument. That is not one of my company's products and so I am not familiar with it. Your best technical support would come from the instrument's manufacturer.

I can make one suggestion with respect to your A-scan image (image 5). Because there does not appear to be a time scale on the screen, I do not know if you are detecting a valid backwall echo. If you have not already done so, I would suggest that you perform the simple test I described earlier... rub your finger on the back side of the test piece. The backwall echo will be damped when you couple a finger to the back side. Any echo that doe snot dampen is either an internal reflection caused by the structure of the composite, or a second multiple of the water path (front surface) echo.

"As your advice for calibration in #2, if I'm using polystyrene but almost third times thicker (~20mm) than my GFCL sample (7.4mm), can I simply just devide into 3 for the final result? (because it hard for me to find polystyrene <20mm)"

No. Use the actual thickness of your test piece in the calculation. If you are using 30 mm polystyrene, then the calculation will be

30 mm / [measured transit time divided by 2 ] = velocity

1
 
 Reply 
 
Tengku asyraf
NDT Inspector,
Malaysia, Joined Jul 2015, 1

Tengku asyraf

NDT Inspector,
Malaysia,
Joined Jul 2015
1
15:46 Jul-08-2015
Re: How to determine material velocity and time of flight of hand lay-up Glass Fiber Composite Laminate (GFCL) material?
In Reply to Tom Nelligan at 15:27 Jul-08-2015 .

Hi mate...

i'm too interest about your subject.

Fyi, i'm grad university tun hussein 2010. My thesis also simillar this subject. maybe you will find it library. You can use as your guide and refrence.

1
 
 Reply 
 
Faisal
R & D,
Universiti Tun Huseein Onn Malaysia, Malaysia, Joined Feb 2014, 4

Faisal

R & D,
Universiti Tun Huseein Onn Malaysia,
Malaysia,
Joined Feb 2014
4
07:15 Jul-09-2015
Re: How to determine material velocity and time of flight of hand lay-up Glass Fiber Composite Laminate (GFCL) material?
In Reply to Tengku asyraf at 15:46 Jul-08-2015 .

Thank you Tom Nelligan for your support.. Here I enclosed screen shoot of A-scan signal as follow your tips (by rubbing wet test piece on the back side of GFCL sampel).. So, I can confirm that second peak was backwall echoes right?

(image 6) https://copy.com/OID7alUKtNzy6Q0b

**********************************

Thank you Tengku Ashraf for your intention.. btw, what is your thesis title?
Hmm.. unfortunately I'm on study leave now and not able to get your thesis in library.. Really appreciate if you can share .pdf through my email (pecal491@gmail.com)



 
 Reply 
 

Product Spotlight

MANTIS

MANTIS is a compact, powerful and affordable flaw detector (16:64PR), dedicated to field operators
...
. This portable equipment offers standard (electronic-, sector-, compound scan, conventional UT for pulse-echo, dual array and TOFD inspections), and advanced phased-array (real-time TFM -Total Focusing Method). MANTIS benefits from the same intuitive and user-friendly interface (CAPTURE) than Gekko for easier inspections.
>

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.
>

ISAFE3 Intrinsically Safe Sensor System

ISAFE3 intrinsically safe sensor system of Vallen Systeme is especially targeted at the petrochemica
...
l - as well as oil and gas transportation industry. The sensor system is designed for permanent monitoring or periodic inspection tasks. Sensors are available for different AE-frequency ranges optimized for corrosion and fatigue crack detection and other applications. The ISAFE 3 sensor system consists of an AE-sensor (model ISAS3) certified according to ATEX/IEC for installation in zone 0, gas group IIC, IP68, 20 to +60 °C, and a signal isolator (model SISO3) certified for installation in zone 2. An ISAS3 sensor can be mounted in atmosphere or submerged, e.g. in water or crude oil. It is supported by mounting tools for temporary (magnets) or permanent (welded) installation. ISAFE3 supports automatic sensor coupling test and can be used with any AE signal processor supporting 28V supply at 90 mA peak, e.g. Vallen Systeme ASIP-2/A.
>

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.
>

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