Enhancement of Time Resolution in Ultrasonic Time-of-Flight Diffraction Technique With Frequency-Domain Sparsity-Decomposability Inversion (FDSDI) Method
Enhancement of Time Resolution in Ultrasonic Time-of-Flight Diffraction Technique With Frequency-Domain Sparsity-Decomposability Inversion (FDSDI) Method
复制标题
利用频域稀疏可分解性反演（FDSDI）方法增强超声飞行时间衍射技术的时间分辨率
DOI：
10.1109/tuffc.2021.3087754
复制
发表时间：
2021-06
期刊：
影响因子：
--
通讯作者：
Jin Shijie
中科院分区：
文献类型：
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作者：
Sun Xu;Lin Li;Ma Zhiyuan;Jin Shijie
由于超声飞行时间衍射（TOFD）技术存在上下尖端侧波和绕射波的叠加现象，因此缺乏时间分辨率限制了浅次表面缺陷的定量检测。本文提出了基于超声反射序列的稀疏性和可分解性的频域稀疏分解反演（FDSDI）方法，以提高TOFD的时间分辨率。将${l}_{{1}}$ -和${l}_{{2}}$ -范数约束组合为频域优化问题。模拟采用碳钢模型，其中包含一系列深度为2.0、2.5、3.0、3.5和4.0 mm的浅次表面裂纹。缺陷深度和高度的相对测量误差不超过6.57%，死区深度减小70%。随后，在带有人工缺陷的碳钢试样上进行了FDSDI方法的可行性实验验证。计算缺陷深度和高度，相对误差在6.0%以内。最后，讨论了FDSDI方法的检测能力，并通过实验分析了频率带宽、正则化参数和噪声对反演结果的影响。结果表明，FDSDI方法对多个重叠信号进行解耦，显著提高了时间分辨率，可以量化死区内的小缺陷。
The lack of time resolution restricts the quantitative detection of shallow subsurface defects with ultrasonic time-of-flight diffraction (TOFD) technique due to the superposition between lateral wave and diffracted waves from upper and lower tips. In this article, the frequency-domain sparsity-decomposability inversion (FDSDI) method was proposed to enhance the time resolution in TOFD based on the sparsity and decomposability of the ultrasonic reflection sequence. An optimization problem was formulated in the frequency domain by combining ${l}_{{1}}$ - and ${l}_{{2}}$ -norm constraints. The simulation was performed with a carbon steel model containing a series of shallow subsurface cracks at the depths of 2.0, 2.5, 3.0, 3.5, and 4.0 mm. The relative measurement errors of defect depths and heights were no more than 6.57%, and the depth of the dead zone was reduced by 70%. Subsequently, the feasibility of the FDSDI method was experimentally verified on a carbon steel specimen with an artificial defect. The defect depth and height were calculated with relative errors within 6.0%. Finally, the detection capacity of the FDSDI method was discussed, and the effects of frequency bandwidth, regularization parameter, and noise on inversion results were analyzed by experiments. It is concluded that the FDSDI method decouples the multiple overlapped signals and significantly improves the time resolution to quantify the small defects in the dead zone.