Carbon crack check
09-21-19, 12:02 AM
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Carbon crack check
Hi,
i've just saw carbon frame check reporte done by profesional team .... full chk. of frame with all cosmetic and structural damage on frame. Well how it is done ? x-ray ? ultrasound ? or .... (except visual chk.)
tnx.
i've just saw carbon frame check reporte done by profesional team .... full chk. of frame with all cosmetic and structural damage on frame. Well how it is done ? x-ray ? ultrasound ? or .... (except visual chk.)
tnx.
09-22-19, 11:12 AM
#2
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I've seen ultrasound used.
X-Ray would probably take it up another level; maybe some places use it, but that's some expensive equipment.
X-Ray would probably take it up another level; maybe some places use it, but that's some expensive equipment.
09-22-19, 07:07 PM
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Why don't you ask the "guy" who did the report? Why should we know their process?
Ultra sound, X ray, Borescope inside the frame are some better methods. Tapping along frame surfaces to detect significant changes of tone, pushing on surfaces to try to detect delaminations, sighting along surfaces to detect kinks or lumps, pulling and prodding drop outs to test for bonding, same with "braze one". The there's the alignment stuff. Does the "guy" have a process to determine alignment that's not just drop out aligning gages or a hanger gage? Andy.
Ultra sound, X ray, Borescope inside the frame are some better methods. Tapping along frame surfaces to detect significant changes of tone, pushing on surfaces to try to detect delaminations, sighting along surfaces to detect kinks or lumps, pulling and prodding drop outs to test for bonding, same with "braze one". The there's the alignment stuff. Does the "guy" have a process to determine alignment that's not just drop out aligning gages or a hanger gage? Andy.
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AndrewRStewart
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09-24-19, 05:43 PM
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My experience says it was an X-ray because that is definitive in the process. Problems with CF are that the delaminations begin with a small point of matrix that did not cure properly. They expand by virtue of movement between the CF layers and that is what leads to failure. Ultra sound only looks for the already delaminated sections and not the underlying breaks in the matrix bonding. HTH, Smiles,MH
09-25-19, 06:03 AM
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That the composite did not cure properly is an interesting idea. Since bikes are fabricated using pre-impregnated carbon/epoxy sheets, as purchased from suppliers, improper cure suggests that the epoxy mixing process has been improperly monitored. This raises the question of what, if any, monitoring or testing procedure was in place. In industrial processes, as for example, fabrication of aluminum or steel structural components, there are industry association standards that must be met. In the carbon composite business I know of no such industry association requirements. Bike manufacturers, if not doing their own testing of the materials they use, rely on prepreg suppliers doing testing, or not.
