ASA 127th Meeting M.I.T. 1994 June 6-10

3pSAa9. Measured phase-speed variation in a steel beam with a T bar.

Ruey-Chang Wei

J. Adin Mann, III

Dept. of Aerosp. Eng. and Eng. Mech., 2019 Black Eng. Bldg., Iowa State Univ., Ames, IA 50011

Residual stress is produced by the welding process that attaches a T bar to a steel beam. A spatially distributed residual stress was built into the plate equation, and the modified wave numbers are solved for. The simulated data show that the residual stress has significant effects on the wave numbers and amplitudes of the waves in the structure. Experimental investigations were conducted on a HY-80 steel beam with a welded T bar. Using a wave-speed tracking technique, the phase speed and arrival time of propagating waves can be computed, and the reflection coefficient at a boundary can be calculated. The phase-speed change over the distance traveled by the wave is detected by this technique as an indication of inhomogeneities in the measured structure. Clear phase-speed decreases were observed near the T bar. The decrease of phase speed around the T bar is a% to 7%, and the reflection coefficient of the T bar is around 0.16. [Work supported by ONR, Grant No. N00014-93-1-0493.]