Abstract
In this paper, the immersion non-collinear shear wave mixing technique is applied to experimentally detect and size vertical fatigue cracks. In the experimental measurements, the amplitude of the generated longitudinal wave from a vertical fatigue crack was first measured over a range of interaction angle of two incident shear waves and ratio of their frequencies. The resulting amplitude parameter space is termed the nonlinear fingerprint of the crack. It is shown that an interaction angle of 110? and frequency ratio of 0.8 lead to the maximum amplitude in the fingerprint. These optimal parameters were used to measure the nonlinear amplitude from various crack positions along its length direction. Finally, an approximate method combining the measured nonlinear amplitudes with the predicated interaction areas of two incident waves was proposed to measure crack length. As expected, the measured crack lengths are around 2~3 mm greater than those measured using the conventional linear ultrasonic phased array images due to the closed fatigue cracks being undetectable with linear arrays.
How to Cite:
Lyu, H. ., Jiao, J. ., Zhang, J. . & Croxford, A. ., (2019) “The sizing of fatigue cracks using non-linear shear wave mixing method”, Review of Progress in Quantitative Nondestructive Evaluation .
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