摘要
针对表面裂纹深度和取向的无损表征难题,提出一种基于临界折射纵波(L_(CR))的检测方法。以碳钢试块表面垂直裂纹(深度为1~8 mm)、倾斜裂纹(长度为10 mm,倾角为15°~90°)为检测对象进行试验,分析了裂纹深度、取向对L_(CR)波信号的影响规律,通过信号幅值和B扫描成像表征裂纹。试验结果表明,L_(CR)波在传播过程中会受到表面裂纹的遮挡作用,并在裂纹尖端产生衍射。随裂纹深度增加,遮挡作用增强,透射L_(CR)波幅值下降且到达时刻延后,对裂纹取向不敏感;B扫描图像中L_(CR)波及对应尖端衍射波的位置、方向与裂纹的深度、取向具有良好的一致性。该检测方法为表面裂纹的有效表征提供了新思路。
Aiming at the characterization of the depth and orientation of a surface crack, a nondestructive testing method using critically refracted longitudinal(L_(CR)) wave was proposed. The carbon steel test block containing vertical cracks(1~8 mm depth) and oblique cracks(10 mm length, 15°~90° inclination angle) were tested. The effects of depth and orientation were analyzed. The amplitude of L_(CR)wave and the B-scan imaging were used to determine the depth and orientation. Results showed that L_(CR)wave was blocked and diffracted wave from the crack tips was also observed. As the crack depth increased, the blocking effect of L_(CR)waves increased, leading to a decrease in the amplitude of transmitted L_(CR)waves. However, it was not sensitive to the crack orientation. At the same time, the arrival time of L_(CR)wave was delayed. B-scan images were reconstructed by the change of the diffracted wave with both crack depth and orientation, which provided a new idea for the qualitative assessment of surface cracks.
作者
孟亦圆
林莉
罗忠兵
MENG Yiyuan;LIN Li;LUO Zhongbing(NDT&E Laboratory,Dalian University of Technology,Dalian 116024,China)
出处
《无损检测》
CAS
2021年第12期17-20,共4页
Nondestructive Testing
基金
国家自然科学基金项目(51775087)
大连市高层次人才创新支持计划(2018RQ40)。
关键词
表面裂纹
临界折射纵波
裂纹深度
裂纹取向
surface crack
critically refracted longitudinal wave
crack depth
crack orientation
