Strain gages on composites 1

[cwc93]

Are conventional metal foil strain gauges presently being used to monitor delamination in composite materials? And if so what sensitivity is required (micro strain range)? Do the strain gauges have to be right on the delamination to detect the delamination or can they be a distance away and still detect the delamination?

Thanks

 

[Compositepro]

I'm not aware of strain gages being used to detect delamination. Although it certainly is posible to develop such techniques their application would be very limited compared to other techniques such as ultrasonics, holography or pulsed thermography which give detailed pictures of delaminations.

 

[USACompositeGuy]

Please explain your application in a little more detail. I am aware of normal strain gages being used in initial testing to get accurate load values and to determine DTA analysis methods for damages such as delamination that is already present on the part. It may be possible to distinguish common load conditions that may be present on or very near delamination, but I cannot see that the strain gage would be able to detect delamination in any ply other than the outer layer. And it would only be effective at the location of the damage.

Like Compositepro said, other NDT methods are much more effective at finding delam. than a strain gage.