Advanced science.  Applied technology.


Eddy Current Testing for Measuring Residual Stress Around Cold-Worked Holes: 11,125,723


A method of testing the residual stress around a cold-worked hole in a test material. The test uses two identical eddy current coil pairs, each pair having a driving coil and a pickup coil. One coil pair is placed into the cold-worked hole. The other coil pair is placed into a non-cold worked hole in a reference material. When the coils are activated, and with a properly chosen phase difference between the excitation signal and the output signal, the in-phase component of the output voltage signal can be correlated to residual stress around the cold-worked hole.

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Teodor Dogaru; Clinton J. Thwing; Darryl Wagar