基于边界相切拟合的轴对称工件缺陷重构方法

Reconstruction for Flaw in Axisymmetric Workpiece Based on Boundary Tangent Principle and Fitting Technology

针对轴对称工件超声检测缺陷重构问题,通过分析传统基于传播时间反演方法的不足和误差产生的原因,提出了一种基于边界相切拟合的缺陷重构方法,并针对实际检测缺陷的类型,采用圆和椭圆作为模型对缺陷进行重构。从重构结果上看,当检测实心体工件时,圆形缺陷的圆拟合重构误差不大于0.1 mm,圆形缺陷的椭圆拟合重构误差小于0.4 mm,椭圆形缺陷的椭圆拟合重构误差小于0.3 mm,空心体工件由于检测方式不同,误差会比实心体大一些。

Ultrasonic is used to detect the flaw in the axisymmetric workpiece. This paper analyzes the reason for the shortage and the error of the tradition reconstruction method based on travel time, and proposes an improved reconstruction method based on boundary tangent principle and fitting technology. The circle model and ellipse model are used respectively. The results show that for the workpiece with solid body, the errors are not more than 0.1 mm when circle model used for circle flaw, and the errors are less than 0.4 mm when ellipse model used for circle flaw, and the errors are less 0.3mm when ellipse model used for ellipse flaw. The results also show that the workpiece with hollow body has bigger error than that with solid body, because ultrasound is in normal incidence mode for the former, and in off-center incidence mode for the latter.