( 1) 真空气体泄漏现象能够激发大量的声发射信号,泄漏声发射信号覆盖了低频到高频的多个频带,真空泵运行的本底振动信号能量集中在低频频带,做声发射真空泄漏分析时应该先消除真空泵运行的本底振动信号来提高泄漏声发射信号的信噪比。
( 2) 基于平均频谱原理分析了不同孔径的泄漏孔产生的声发射信号平均时域波形及平均频谱,结果表明,经过平均运算后的声发射信号参数特征有较强的可区分性,尤其是在不同孔径漏孔的声发射信号幅值相差较大,而泄露孔径是与泄漏量大小直接相关的,这样就为基于声发射技术的泄漏量预测奠定了基础。
( 3) 从小波包归一化能量特征分布图看,三种不同孔径泄漏声发射信号的归一化能量特征分布既有一定的相似性,又不尽相同,但都明显区别于真空泵本底振动信号能量分布特征。综上所述,基于声发射技术的真空泄漏在线检测技术有较高的可行性,真空泄漏模拟实验的分析结果表明,该技术的应用价值体现在真空泄漏现象的定性判断上。同时,本文的研究为泄漏量的预测和泄漏阶段的判定提供了一种新的在线无损检测方法。
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