电子测量与仪器学报

王军,李强鑫,吴寅,顾佳健.脉冲压缩的木材空气耦合超声检测研究[J].电子测量与仪器学报,2022,36(3):47-52

脉冲压缩的木材空气耦合超声检测研究

Air-coupled ultrasonic testing of wood based on pulse compression technology

DOI：

英文关键词:wood defects air-coupled ultrasonic testing pulse compression coded excitation

基金项目:国家自然科学基金（31700478，32171788）、江苏省高校优秀中青年教师和校长境外研修计划（2019070）、南京林业大学自制实验教学仪器项目（2021017）资助

作者	单位
王军	1.南京林业大学信息科学技术学院
李强鑫	1.南京林业大学信息科学技术学院
吴寅	1.南京林业大学信息科学技术学院
顾佳健	1.南京林业大学信息科学技术学院

Author	Institution
Wang Jun	1.School of Information Science and Technology, Nanjing Forestry University
Li Qiangxin	1.School of Information Science and Technology, Nanjing Forestry University
Wu Yin	1.School of Information Science and Technology, Nanjing Forestry University
Gu Jiajian	1.School of Information Science and Technology, Nanjing Forestry University

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中文摘要:

为解决木材和空气介质之间声阻抗不匹配引起超声波衰减大,导致检测信号的信噪比低、测量精度不高等问题,本文将相位编码脉冲压缩技术应用到木材空气耦合超声检测系统。采用巴克码序列作为相位编码方式,分析了脉冲压缩激励信号产生和接收信号经互相关匹配滤波器后解调检测原理。以有节子和裂纹缺陷的木材作为实验对象,通过单点扫描对比缺陷处与非缺陷处检测信号的差异,最后使用 C 扫描对木材缺陷检测精度进行定量分析。结果表明,相比正弦激励信号,采用 13 位巴克码作为编码激励信号可使检测信号的信噪比提高了 9. 12 dB,C 扫描结果对节子型缺陷定量识别精度为 90%,且能有效检测节子中宽度为 1 mm 的裂纹。验证了基于脉冲压缩的木材空气耦合超声检测无需与被测材料接触,也能够有效提高木材缺陷识别能力。

英文摘要:

In order to solve the problem of the acoustic impedance mismatch between wood and air medium and the large attenuation of ultrasonic. These are the reasons that the signal-to-noise ratio of the detection signal is low and the measurement accuracy is not high. The phase coded pulse compression technology was applied to the air coupled ultrasonic detection of wood in this paper. Buck code sequence was selected as phase coding sequence, and the principle of generating and receiving signal demodulation of impulse compression excitation signal was detailed. The defect wood was used as the experimental object, and the difference of the detection signal between the defect and the non-defect was compared by single point scanning testing. Then the accuracy of wood defect detection was quantitatively analyzed by C-scan experiments. The results show that the signal-to-noise ratio of the detection signal is improved by 9. 12 dB when 13-bit buck code is used as the coding excitation signal, compared with sinusoidal excitation signal. The quantitative recognition accuracy of the defect for the node is 90% by C-scan results. The crack with width of 1 mm in the node can be detected effectively. These show that the application of pulse compression technology to the air coupled detection of wood can effectively improve the wood defect identification ability.

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