Research on Vertical Crack Detection Method with Multi-Mode TFM

Total Focusing Method (TFM) is an advanced ultrasound array data post-processing imaging algorithm, which shows great potential in defect detection and characterization. By changing the path of the focused sound beam, defects can be detected in multiple directions. In this paper, a variety of full-focus simulations and experiments of sound beam path focusing are carried out for the more harmful vertical cracks, and the detection and evaluation are conducted. The following results are obtained: The Direct Mode can perform fixed-length detection of the lower surface cracks, but can't be shaped; The Half-Wave Mode can not only fix the length of the bottom surface cracks, but also fix the shape; The Full-Wave Mode can only fix the length detection of the upper surface cracks; The Full-Wave + Mode can not only fix the length but also shape the detection of the upper surface cracks. The research results show that when detecting defects, for detecting vertical cracks at different positions, choosing an appropriate mode will be more beneficial to the detectable rate and quantitative evaluation of defects.