超声检测信号的频谱分析与软件设计

【作者】 刘静；

【导师】 杨思乾；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2002， 硕士

【摘要】 论文根据离散傅立叶变换及逆变换原理，用C语言和汇编语言编程设计了高频超声信号的频谱分析软件。软件系统具有幅频图及相频图的绘制、最高峰值、谐波系数及有效谱宽度的计算及显示等功能，从而为超声信号的频谱分析提供了极其有效的技术手段。 研究发现，超声信号的采样频率、采样特征点、闸门位置及闸门宽度对超声信号的FFT及IFFT结果有明显的影响。本文的试验分析结果表明，对于中心频率为15MHz的水浸聚焦探头，其采样频率应不低于90MHz，闸门宽度为1.2us，特征点的采样误差应不大于20％。 论文还运用所编制的分析软件，对不同热处理状态下的45钢超声检测信号进行了初步的谱分析，结果表明不同金相组织的超声检测信号频谱有明显不同。因此，运用谱分析技术对热处理组织进行无损检测是可行的。更多还原

【Abstract】 According to Fourier Transform Principle, a program is designed with C and Assemble words to analyze the high frequency ultrasonic signals in frequency domain in this paper. There are functions such as drawing the chart of amplitude-frequency and phase-frequency, calculating and displaying the highest peak value, the total sum of amplitude and the effective line-breadth of the signal in the program. So an effective technical means is supplied for the analysis of ultrasonic signal.The research results show that the influence of sampling frequency, sampling error of peak value, strobe-position and strobe-width on FFT and IFFT is obvious. For 15MHz immersion focusing ultrasonic testing signal, the proper sampling frequency is 90MHz, the appropriate strobe-width is 1.2us and the sampling error less than 20%.The 45 steel samples, which were treated by different heating and cooling methods, were tested and the testing signal were analyzed elementarily in frequency domain using the program. The results show that for the ultrasonic testing signals of different microstructure, the difference in frequency domain is distinguishable. So the technique of analysis in frequency domain is feasible for the nondestructive testing of different heating treatment microstructure.更多还原