Frequency-time characteristics of air-borne signals from laser welds
Frequency-time characteristics of air-borne signals from laser welds
复制标题
DOI：
10.2351/1.4745403
复制
发表时间：
1996-02-01
影响因子：
2.1
通讯作者：
Young, R
中科院分区：
文献类型：
--
作者：
Farson, D;Hillsley, K;Young, R
对不锈钢薄板激光搭接焊缝的声发射进行了记录和分析。从焊缝发出的声信号被感测与仪器麦克风和使用短时傅立叶频谱分析，以表征其时间-频率分布。已确定，优质全熔透焊缝的声谱可与劣质焊缝的声谱区分开来，劣质焊缝定义为部分熔透焊缝或在被连接的板材之间具有间隙的焊缝。一种新的，相对简单的分类器的基础上的总能量的频带从1到2千赫正确区分完全渗透从部分渗透超过90%的时间平均。在此范围内，部分熔透焊缝的能量低于全熔透焊缝。一个稍微复杂的方法，结合时间平均被认为是能够预测的可靠性接近100%的一些焊缝，但在一些异常情况下，少得多的渗透。这种相对简单的分类算法的性能被证明是可比的，在以前的工作中发现的基于神经网络的分类。在初步试验中，基于总信号能量的分类器能够识别有间隙的搭接焊缝和无间隙的搭接焊缝。
The acoustic emissions from laser lap welds in stainless steel sheet were recorded and analyzed. The acoustic signals emanating from the weld were sensed with an instrument microphone and analyzed using short-time Fourier spectra to characterize their time-frequency distributions. It was determined that the acoustic spectrum of good-quality, full-penetration welds could be differentiated from the spectra of poor-quality welds, defined as either partial-penetration welds or welds having a gap between the sheets being joined. A novel, relatively simple classifier based on total energy in the frequency band from 1 to 2 kHz correctly discriminated full penetration from partial penetration over 90% of the time on average. Partial-penetration welds had less energy in this range than did full-penetration welds. A slightly more sophisticated approach incorporating time-averaging was found to be capable of predicting penetration with reliability approaching 100% for some welds but much less in some anomalous cases. The performance of this relatively simple classification algorithm was shown to be comparable to that found in previous work using neural network-based classifiers. A classifier based on total signal energy was shown in preliminary trials to be capable of recognizing gapped lap welds from nongapped lap welds.