Southwest Research Institute

Darryl Wagar

Hegeon Kwun

Sergey A Vinogradov

Clinton Thwing

Teodor Dogaru

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.

Eddy current testing for measuring residual stress around cold-worked holes

A sensor for use in magnetostrictive testing of a structure. An array of sensor elements is attached to a flexible backing. Each sensor element has a thin strip made from magnetostrictive material, a first coil wrapped around the width of the strip and operable to provide a DC bias magnetic field, and a second coil wrapped around the width of the strip and operable for MsS generation and detection. Typically, the first coils of all strips are electrically connected to each other and the second coils of all strips are electrically connected to each other, to form two separate coil circuits. The probe may be wrapped around the circumference of a cylindrical structure, and used for magnetostrictive testing.

Growing community of inventors

San Antonio, TX, United States of America

Darryl Wagar