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Radiographic test for carbon fiber frame

Posted: Thu Sep 20, 2007 11:32 am
by Infin1ty
I want to check a frame for cracks, is a radiographic test (NDT) is the test i should be looking after?
Is this test a realiable one for carbon parts?

Thanks.

Posted: Thu Sep 20, 2007 12:04 pm
by KB
Must admit I've never heard of it on CF although I think it's possible. But normally they would be checking things much thicker than bikes.

NDT is normal on metals, usually carbon, stainless, and other duplex steels.

Posted: Thu Sep 20, 2007 12:04 pm
by Weenie

Posted: Thu Sep 20, 2007 12:45 pm
by Taz
It can be done, though it would cost a lot of money to cover all of the frame and radiograph it from various angles to find any cracks.
Here are some photos:

Image

Image

Image

Posted: Thu Sep 20, 2007 12:56 pm
by San Marco
Good pictures but be warned look term exposure to x-ray is not good for your frames health :wink:

Posted: Thu Sep 20, 2007 1:34 pm
by ALE
Quizz : which bike is it? :lol:

Posted: Thu Sep 20, 2007 1:38 pm
by RTW
Orbea with Campy?

Posted: Thu Sep 20, 2007 1:47 pm
by frd
Orbea Orca, but the brakes are clearly Dura Ace (look at the small plastic thing on the cable adjuster). Also front der looks dura ace, but the cranks? FSA maybe?

Posted: Thu Sep 20, 2007 1:51 pm
by Giant DK
frenk wrote:FSA maybe?


My guess too! Looks lige FSA/DA type of chainrings and torx screws!

Posted: Thu Sep 20, 2007 1:52 pm
by Infin1ty
It was done by an insurance company, they only checked about 5 points! they said the frame is fine.
I still say the frame is not rideable and i am sure because i have a crack in the seatpost (its an integrated one, BH G-1) and it was tested with the seapost! and a few other imperfections places on the carbon.
I was hit by a car.
so actually this test is worthless?

Posted: Thu Sep 20, 2007 1:56 pm
by frd
Infin1ty wrote:It was done by an insurance company, they only checked about 5 points! they said the frame is fine.
I still say the frame is not rideable and i am sure because i have a crack in the seatpost (its an integrated one, BH G-1) and a few other imperfections places on the carbon.
I was hit by a car.
so actually this test is worthless?

If it's an integrated seatpost and has a crack, they should have saved the money of the test! Not rideable to me!

Giant DK wrote:My guess too! Looks lige FSA/DA type of chainrings and torx screws!

Reminds me of that thread with title "You know you have ridden too much when..." :lol:

Posted: Thu Sep 20, 2007 1:58 pm
by Taz
The test is not worthless, but you have to look at the right places and shoot at the right angle. Unfortunatelly there is very little way of knowing which are the places/angles

Posted: Thu Sep 20, 2007 2:29 pm
by Hosehead
KB wrote:NDT is normal on metals, usually carbon, stainless, and other duplex steels.

It is also normal on composite structures, altough the tests are often different.

Posted: Thu Sep 20, 2007 2:50 pm
by ScienceIsCool
In really thin composite structures (like a bike) I hear that the only reliable way to detect cracks or delamination is with a dye penetrant test. Apparently, it's exactly what it sounds like. The part is soaked in a tagged (UV marker, magnetic, or other) fluid, cleaned, and then illuminated to check for otherwise invisible cracks.

X-Rays will miss small or thin cracks completely, just like when doctors miss bone fractures. Poor contrast, diffraction, and resolution make it difficult.

John Swanson

Posted: Thu Sep 20, 2007 3:49 pm
by Infin1ty
ScienceIsCool wrote:In really thin composite structures (like a bike) I hear that the only reliable way to detect cracks or delamination is with a dye penetrant test. Apparently, it's exactly what it sounds like. The part is soaked in a tagged (UV marker, magnetic, or other) fluid, cleaned, and then illuminated to check for otherwise invisible cracks.

X-Rays will miss small or thin cracks completely, just like when doctors miss bone fractures. Poor contrast, diffraction, and resolution make it difficult.

John Swanson

Do you have any reference which i can use it against the insurance company? something that will help me in court
I'm sick of them, they took their time for about a year, i'm going to take a lawsuit against them.

They always find "new things", for example, when the car hit me i crashed on my helmet really hard, there is a crack inside the helmet, but outside only minor scratches on the sticker which was removed, now they say because they don't see any big scratches i can use the helmet and it shows i didn't crash. (just to show you how "stupid" they act like).

Posted: Thu Sep 20, 2007 5:50 pm
by ScienceIsCool
Long link

It's tough, because a lot of the data has not been compiled into a single white paper on detecting damage in thin composites. Not that I know of, anyways. But there is a lot of data, like in the enormous link above. The authors found that the actual damaged area of a tube was 10 times larger than what was found via ultrasound.

John Swanson

Posted: Thu Sep 20, 2007 5:50 pm
by Weenie