基于逆时偏移的底面开口裂纹高精度超声成像及定量分析

High-precision ultrasonic imaging and quantitative analysis of bottom opening cracks based on reverse time migration

传统的超声成像方法只能使用一次反射波对缺陷的上端进行成像,而基于逆时偏移的超声成像方法可使用多次反射波对缺陷进行完整的成像。该项研究将一种基于逆时偏移的超声成像方法用于对底面开口裂纹的高精度成像和定量分析。在数值仿真方面,对底面识别的必要性和高成像精度进行说明。在实验方面,对具有多个底面开口裂纹的铝块进行底面识别,进而对底面开口裂纹进行完整成像。综合考虑底面识别前后的逆时偏移成像结果,可对底面开口裂纹的长度和宽度进行直观的定量分析。最后,针对逆时偏移成像在超声无损检测方面的应用,给出对缺陷进行完整成像及定量分析的3个关键的步骤。

The traditional ultrasonic imaging method can only use one reflected wave to image the upper end of the defect,while the ultrasonic imaging method based on reverse time migration can use multiple reflected waves to image the defect completely.In this study,a ultrasonic imaging method based on reverse time migration is used for high-precision imaging and quantitative analysis of bottom opening cracks.In terms of numerical simulation,the necessity of bottom identification and high-precision imaging are explained.In terms of experiments,the bottom identification of an aluminum block with multiple bottom opening cracks are performed,and then the bottom opening cracks are completely imaged.Considering the reverse time migration imaging results before and after identification of the bottom surface,the length and width of the bottom opening crack can be quantitatively analyzed intuitively.Finally,for the application of reverse time migration imaging in ultrasonic non-destructive testing,three key steps for complete imaging and quantitative analysis of defects are given.