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Signal processing methods for second harmonic generation in thin specimens

机译：薄样品中二次谐波产生的信号处理方法

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摘要

This research explores five available signal processing methods: discrete Fourier transform (DFT); least squares method; original Prony method; least squares (LS) Prony method; and known poles (KP) Prony method, to accurately analyze the harmonic content of a tone-burst signal obtained from the second harmonic generation (SHG) measurement. Accurately obtaining the correct frequency content is especially important when the number of cycles is limited by the thickness or high attenuation of a specimen. Results from both numerically generated synthetic signals and experimental data from a specimen demonstrate that the least squares and KP Prony methods provide the most consistent and accurate results for tone-burst signals with low number of cycles. The conventional DFT provides accurate harmonic amplitudes only when the effective number of cycles (neff) is eight or higher. The least squares and KP Prony methods are then applied to a set of thin binary Fe-1.0% Cu alloy specimens where the changes in the nonlinearity parameter,β,as a function of heat treatment time is determined. Theβparameters processed with these two methods produce trends that make better physical sense than processing with the original Prony method.
机译：这项研究探索了五种可用的信号处理方法：离散傅里叶变换（DFT）；离散傅里叶变换（DFT）；离散傅立叶变换（DFT）；以及离散傅里叶变换。最小二乘法原始的Prony方法；最小二乘（LS）Prony方法;和已知极点（KP）Prony方法，以准确地分析从二次谐波生成（SHG）测量获得的音猝发信号的谐波含量。当循环数受样品的厚度或高衰减限制时，准确获得正确的频率含量尤为重要。来自数字生成的合成信号和来自样本的实验数据的结果都表明，最小二乘和KP Prony方法可为周期数少的音爆信号提供最一致，最准确的结果。仅当有效周期数（neff）为8或更高时，常规DFT才能提供准确的谐波幅度。然后，将最小二乘和KP Prony方法应用于一组薄的二元Fe-1.0％Cu合金试样，确定非线性参数β随热处理时间的变化。与原始Prony方法相比，用这两种方法处理的β参数产生的趋势具有更好的物理意义。

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  • 来源
    《NDT & E international》 |2018年第4期|57-64|共8页
  • 作者

    Katherine Scott; Jin-Yeon Kim; Laurence J. Jacobs;

  • 作者单位

    G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology;

    School of Civil and Environmental Engineering, Georgia Institute of Technology;

    G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology,School of Civil and Environmental Engineering, Georgia Institute of Technology;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
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