On Microwave Dual Frequency Technique for Evaluation of Surface Cracks
A method to estimate crack closure stress on the crack surface was introduced. The crack closure stress was estimated based on the compliance technique, while crack depth was measured by means of the microwave dual frequency technique. The effect of crack closure stress on detection and evaluation of a closed crack in a carbon steel by using the microwave dual frequency technique was discussed in details.
Kikuo Kishimoto, Masanori Kikuchi, Tetsuo Shoji and Masumi Saka
M. Saka et al., "On Microwave Dual Frequency Technique for Evaluation of Surface Cracks", Key Engineering Materials, Vols. 261-263, pp. 955-962, 2004