Ultrasonic Measurement of the Crack Depth and the Crack Opening Stress Intensity Factor Under a No Load Condition
Ultrasonic Measurement of the Crack Depth and the Crack Opening Stress Intensity Factor Under a No Load Condition
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空载条件下裂纹深度和裂纹张开应力强度因子的超声波测量
DOI：
10.1023/b:jone.0000045220.19233.c3
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发表时间：
2004
影响因子：
2.8
通讯作者：
M. Akanda
中科院分区：
文献类型：
--
作者：
M. Saka;M. Akanda
本文介绍了一种利用超声波技术估算闭合小裂纹裂纹深度和裂纹张开应力强度因子的新方法。在钢试件中，考虑了深度为0.4~4.0 mm的表面连通的后墙裂纹。采用50°入射材料的超声横波波束的裂纹拐角回波幅度。首先，确定开口裂纹的超声回波响应是裂纹深度的函数。其次，在改变裂纹闭合应力的基础上，建立了裂纹闭合应力与裂纹回波响应之间的经验关系式。基于这些关系，通过对未知闭合裂纹的超声响应进行反分析，确定了该裂纹的裂纹深度和闭合应力。根据估算的裂纹深度和裂纹闭合应力，确定裂纹张开应力强度因子。通过将评估的裂纹深度与实际裂纹深度进行比较，验证了该无损评估方法的准确性和可靠性。后者是在进行超声波检测后得到的断口表面上测量的。结果表明，该方法是定量、无损评价裂纹深度和闭合应力的有力工具。
This paper describes a new methodology for evaluating the crack depth and the crack opening stress intensity factor of small closed cracks using an ultrasonic technique. Surface connected back-wall cracks of depth ranging from 0.4 to 4.0 mm in steel specimens are considered. The crack corner echo amplitude of an ultrasonic shear wave, SW, beam of 50° incidence in material is used. First, the ultrasonic echo response of an open crack is determined as a function of crack depth. Next, based on changing the crack closure stress, an empirical relation between the crack closure stress and the crack-echo response is formulated. The crack depth and the crack closure stress of an unknown closed crack based on these relations are determined by inverse analysis of the ultrasonic response of the crack. From the evaluated crack depth and crack closure stress, the crack opening stress intensity factor is determined. The accuracy and reliability of this new nondestructive evaluation (NDE) method is verified by comparing the evaluated crack depth with the actual one. The latter is measured on the fractured surface obtained after carrying out ultrasonic testing. The ultrasonic method developed is proved to be a powerful tool for quantitative and nondestructive evaluation of the crack depth as well as the crack closure stress.