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针对薄层结构超声检测中,薄层上下界面反射波发生混叠,界面回波难以识别的难题,采用连续小波变换模极大值(W avelet T ransform M odu lusM ax im a-W TMM)方法,对A l表面厚度约270μm的环氧树脂薄层进行了厚度检测。通过对M arr和M orlet两种基本小波的比较,发现M arr小波特别适合于突变信号的检测,提出了一条针对薄层厚度进行超声测量的技术路线。实例分析表明,该技术具有较高的界面回波辨识能力,并有较强的噪声适应性,能准确测量薄层的厚度,具有较好的应用价值。
In the ultrasonic testing of thin-layer structure, the reflection waves at the upper and lower layers of the thin layer are aliased and the interface echo is difficult to identify. The method of continuous wavelet transform modulus maxima (Wavelet T ransform Moductus ax imWMW) A l A surface thickness of about 270μm thick epoxy resin layer was tested. By comparing the two basic wavelets M arr and M orlet, it is found that the M arr wavelet is especially suitable for the detection of the abrupt signal, and a technical route for ultrasonic measurement of the thickness of the thin layer is proposed. The case study shows that this technique has high interfacial echo identification ability, strong noise adaptability, accurate measurement of the thickness of thin layer and good application value.