【作者】 张正；

【导师】 宋光德；

【作者基本信息】 天津大学 ， 精密仪器及机械， 2007， 硕士

【摘要】 超声波数字检测技术在无损检测中有着重要的作用。超声波探伤信号的数字滤波和数字检波是根据对超声波回波信号的采样点进行相关的数字信号处理,重构出其波形的包络线,准确定位出回波的峰值和波峰时间值,从而来确定缺陷大小及其在焊缝中的位置。该方法具有检测速度高、处理灵活、适应范围广泛、精度高以及检测方便等优点,随着计算技术和信息技术的高速发展,它必将越来越受到人们的关注。本课题以超声波探伤的基本原理和数字信号处理的基本方法为基础,根据实际使用需要设计出了超声波探伤信号的预处理硬件电路以及数字带通滤波器和数字检波器,并根据实验结果验证其正确性。本课题完成的主要工作1.详细论述了超声波探伤的基本原理和数字信号处理的基本方法,并分析将两者合理结合在一起的方案,提出了相应的数学处理模型。2.设计了数字滤波和数字检波相应的前端预处理硬件电路,实现了超声波回波信号的准确采集。3.提出了超声波探头实际发射频率的自动识别方法,利用分段扫频技术实现了频率自动识别功能,并编写了相关的程序进行验证。4.设计出了超声波信号的数字带通滤波器,并用MATLAB编写了相关的软件程序,对输入的采集信号进行了实验,得到了较好的效果。5.设计出了超声波信号的数字检波器,并用MATLAB编写了相关的软件程序进行测试和实验,得出了满足要求的波形和包络线,并详细分析了实验图形和结果。更多还原

【Abstract】 Ultrasonic digital testing technique has an important function in the field of the nondestructive testing. According to the digital signal processing of the sampling points the digital filtering and detection of ultrasonic echo signal can reconstruct the enveloping curve of the wave, exactly locate echo peak value and its time, and so fix the size of flaw and its location in the welding line. The method has many remarkable advantages such as highly testing speed, flexible processing, wide sphere of application, accurately locating the flaws and convenience etc. Along with the high-speed development of the computing and information technology, certainly it will get more and more attention in future.Based on the basic principles of ultrasonic testing and the basic methods of digital signal processing, this thesis has designed preprocessed hardware circuit, a digital filter and a digital detector according to the need of practical use and validated its correctness by experimental results.The following are main achievements of this thesis:1. Detailed discussion of the basic principles of ultrasonic testing and the basic methods of digital signal processing, analysis of combining both reasonably, putting forward corresponding mathematical processing model.2. Designed the front preprocessed hardware circuit of the digital filter and detector and achieved accurate acquisition of the ultrasonic signal.3. Put forward the automatic identification method of ultrasonic probe actual frequency, used subsection scanning technique to perform this function and compiled correlative program to validate it.4. Designed the digital filter of ultrasonic signal, compiled corresponding MATLAB software procedure, took an experiment towards input acquisition signal and got good results.5. Designed the digital detector of ultrasonic signal, compiled corresponding MATLAB software procedure to take testing and experimenting and got good wave and enveloping curve. Also analyzed the experimental results in detail.更多还原