在TOFD检测中, 由于轴偏离误差的存在, 当缺陷不位于探头连线中心时, 软件对缺陷深度的计算是不精确的, 且缺陷偏离探头连线中心的距离在现有的TOFD软件中不可测量。利用缺陷的变型波信号, 通过测量缺陷纵波衍射信号和变型波信号的时间差, 经程序迭代修正缺陷计算深度值, 进而得到缺陷偏离探头连线中心的距离。理论推导及试验验证了该方法的可行性。使用该方法能够利用现有TOFD图像, 得到缺陷偏心距及精确的缺陷深度信息。

The calculated depth of defect by software is not accurate when the defect is not in the middle of two probes, which due to the existence of the error of axis deviation in the process of TOFD inspection. However the distance between the defect and the middle of two probes cannot be measured by the TOFD software. The signal of transformed wave was made use of, then the time difference among the diffracted longitudinal wave signals of cracks and transformed waves signals was surveyed, and the calculated depth was modified by iterative procedure. Finally the distance of the defect deviating from the middle of two probes was drawn out. The feasibility of this method was verified by the theoretical derivation and experiment. Then the detailed information of eccentricity and accurate depth of defect could be got by using TOFD image.