基于包絡Holder指數的AE信號初至時刻精確拾取
中國測試李 力， 李 驥
聲發射（AE）信號初至時刻精確拾取是聲發射源定位中的關鍵問題，該文探討基于連續小波變換的H?觟lder指數方法拾取AE信號初至時刻，為突出信號初至時刻的奇異性特征，提出對信號包絡估計的包絡H?觟lder指數方法。通過對模擬AE信號和金屬裂紋AE信號應用結果表明：包絡H?觟lder指數可以精確提取AE信號的初至時刻，誤差小于2 μs，能為AE源定位提供一種有效手段。
The identification of the first arrival time of acoustic emission （AE） signal is one of the key problems in AE source location. This paper presented a method of envelope Holder exponent to identify the first arrival time of AE signal. Firstly， the envelope by Hilbert transform was extracted to highlight the singularity character of signal. Then， Holder exponents of the envelope signal were estimated and the curve based on these exponents showed the first arrival time distinctly. Applied the method to AE signals produced by pen lead and metal crack propagation， the first arrival time can be identified correctly. The identified error was less than 2 μs. The research results demonstrated that the proposed method can identified the first arrival time of AE signals precisely.
