作者：张旭¹, 程江¹, 涂君¹, 蔡琛², 宋小春¹

作者单位：1. 湖北工业大学机械工程学院 湖北省现代制造质量工程重点实验室，湖北 武汉 430068;
2. 武汉第二船舶设计研究所，湖北 武汉 430064

关键词：超声检测;经验模态分解;镜像扩展算法;降噪

摘要：

汽车变速箱齿轮焊缝的超声检测过程中，超声回波信号存在信噪比较低导致误检率较高的问题。该文根据齿轮焊缝超声检测信号中噪声的特点，提出利用经验模态分解进行滤波的方法。针对经验模态分解过程中出现的虚假频率现象，提出镜像扩展的解决算法，把镜内信号映射成一个周期性的信号，抑制端点效应，避免虚假频率现象。仿真结果表明该方法可有效提高信噪比且抑制虚假频率的产生，通过标准伤试块的实验结果表明，该文提出的方法可以在较小硬件开销的情况下，有效减小噪声信号干扰，将噪声峰值从高于闸门8.4%降低到低于闸门7.9%，提高检测效率。

Research on signal de-noising method of welded gear ultrasonic testing
ZHANG Xu¹, CHENG Jiang¹, TU Jun¹, CAI Chen², SONG Xiaochun¹
1. Hubei Key Laboratory of Modern Manufacturing Quantity Engineering, School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China;
2. Wuhan Second Ship Design and Research Institute, Wuhan 430064, China
Abstract: In the ultrasonic testing process of the automobile gearbox welding seam, the ultrasonic echo signal has a problem that the signal-to-noise ratio is relatively low, resulting in a high false detection rate. In this paper, according to the characteristics of noise in the ultrasonic detection signal of gear welds, an empirical mode decomposition method was put forward for filtering. In order to solve the false frequency phenomenon when using empirical mode decomposition, the mirror extending algorithm was proposed, which maps the signal in the mirror into a periodic signal to suppress the end effect and avoid the phenomenon of false frequency. The simulation results show that this method effectively improve the signal-to-noise ratio and suppress the generation of false frequency. The experimental results on the standard test block prove that this method effectively reduce interference between the noise and the signal and reduce the peak amplitude of the noise from 8.4% higher to 7.9% lower relative to the value of the gate and improve the detection efficiency with less consumption of hardware.
Keywords: ultrasonic testing;empirical mode decomposition;mirror extending algorithm;de-noising
2021, 47(4):32-37  收稿日期: 2020-04-23;收到修改稿日期: 2020-05-26
基金项目: 国家自然科学基金资助项目(51807052，51707058)
作者简介: 张旭（1987-），女，辽宁瓦房店市人，讲师，博士，研究方向为无损检测
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