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Technical Discussions
Mohamed Karim
Engineering, QC Engineer
Alexandria University, Faculty of Engineering, Egypt, Joined Oct 2010, 6

Mohamed Karim

Engineering, QC Engineer
Alexandria University, Faculty of Engineering,
Egypt,
Joined Oct 2010
6
00:39 Mar-23-2012
PT and composite material

is Liquid pentrant Test is usable method in inspection of Composite material and which composite defects can be detected by pt ?

 
 Reply 
 
Rick Lopez
R & D,
John Deere - Moline Technology Innovation Center, USA, Joined Jul 2011, 191

Rick Lopez

R & D,
John Deere - Moline Technology Innovation Center,
USA,
Joined Jul 2011
191
02:16 Mar-23-2012
Re: PT and composite material
In Reply to Mohamed Karim at 00:39 Mar-23-2012 (Opening).

I've never seen it tried, but if you could prove that staining and chemical compatibility weren't an issue, then penetrant may find surface-breaking flaws. Given that composites are generally comprised of fabric reinforcement of some type, my guess is that background noise would make the test useless. You'd likely have better/faster results with tap-testing, or some type of ultrasonic exam though. I am assuming, of course, that you're talking about applying penetrant to an existing part rather than encapsulating a dye within the composite to indicate surface damage
Regards

 
 Reply 
 
Mohamed Karim
Engineering, QC Engineer
Alexandria University, Faculty of Engineering, Egypt, Joined Oct 2010, 6

Mohamed Karim

Engineering, QC Engineer
Alexandria University, Faculty of Engineering,
Egypt,
Joined Oct 2010
6
07:53 Mar-23-2012
Re: PT and composite material
In Reply to Rick Lopez at 02:16 Mar-23-2012 .

thanks for your valuable information Mr Rick ,so if the PT can be used in finding surface breaking flaws in composite , which is more effective in that, Visual examination ( with magnification and/or without) or Pentrant ?

 
 Reply 
 
Adel
Adel
15:50 Mar-23-2012
Re: PT and composite material
In Reply to Mohamed Karim at 07:53 Mar-23-2012 .

Hello,
I don't know about the kind of defect that you are looking for (I suppose crack detection). But infrared thermal method (IRT) are widely used for composite inspection.
This page gives some tutorial.

http://www.visiooimage.com/en/products_ir_ndt_thermography_tutorial.htm

Regards,

 
 Reply 
 
Norm Woodward
Norm Woodward
16:40 Mar-23-2012
Re: PT and composite material
In Reply to Mohamed Karim at 00:39 Mar-23-2012 (Opening).

I happened to have a copy of ASM Handbook, volume 21, "Composites", and the index, which lists a good number of NDT methods, does not mention "penetrant" and I suspect for good reason.

Of course PT can be used for surface inspections on nearly any solid, but for the expected porosity on a composite surface, let alone potential chemical incompatibllity, this method would have little benefit for detecting cracks or fiber breakage over some other kind of visual.

There may be some new and improved methods and materials, perhaps involving electostatics, that I am not aware of, but I can only imagine this method being used on rather unique composite surfaces.

 
 Reply 
 
Csaba Hollo
,
Retired, Canada, Joined Feb 2010, 301

Csaba Hollo

,
Retired,
Canada,
Joined Feb 2010
301
17:10 Mar-23-2012
Re: PT and composite material
In Reply to Mohamed Karim at 00:39 Mar-23-2012 (Opening).

Recently, we were contacted by a client to carry out a routine disbond examination on the empennage of a Dash-8 aircraft.

When our tech arrived on site, the maintenance tech asked hi if he could do some sort of examination on one of the composite propellor blades, as it was snagged for what appeared to be a dent, and they thought they saw a crack in the surface visually. They wanted to verify it.

I suggested a Type 2 Method A examination (visible water-washable) with a 5 minute dwell time (it was inside a hangar at room temperature). The inspection revealed several circular crack indications surrounding the dent, and a very pronounced linear crack indication running from the dent to the trailing edge.

This was not an 'approved' examination method within our aircraft inspection procedures, but it did tell the tale. A Type 1 Fluorescent would have been overkill, and an absolute bear to clean, and would most likely have had a high background fluorescence due to the porous surface of the composite.

Bottom line is, sometimes you have to think outside the box, and use whatever tools you have in the box. Often the simplest methods are the most appropriate.

 
 Reply 
 
Norm Woodward
Norm Woodward
20:14 Mar-23-2012
Re: PT and composite material
In Reply to Csaba Hollo at 17:10 Mar-23-2012 .

I concer that such use of Type II PT to CONFIRM a crack may be find and dandy.

Specifying such an inspection as a primary method on an aerospace part, particularly on part of the "propulsion" system, would probably get you run off the tarmac, if not out of business. ;^)

To tell you the truth, I hadn't thought of visible dye because it is rarely, if ever, called out in AF procedures, even when probably entirely applicable.

Again, it all depends on surface condition and size of defect being sought.

 
 Reply 
 
Csaba Hollo
,
Retired, Canada, Joined Feb 2010, 301

Csaba Hollo

,
Retired,
Canada,
Joined Feb 2010
301
21:51 Mar-23-2012
Re: PT and composite material
In Reply to Norm Woodward at 20:14 Mar-23-2012 .

Most A/C guys won't think about visible, because it isn't in any specification, NDE manual, service bulletin, etc.

In fact, the mere mention of Type 2 penetrant examination sends most Aircraft NDE specialists into convulsions.

In this case, the primary inspection requirement was 10x visual examination, and the PT was done for the benefit of the inspector...no report of findings was issued.

The maintenance engineer got a nice photograph of some (red) cracking indications.

Would I think of running a whole bunch of helicopter engine components through Type 2 PT examinations? Of course not.

I doubt anyone is looking to have me de-certified as a result of this excercise.

 
 Reply 
 

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