金属杆内疲劳裂纹与振动/超声相互作用及其定量表征

根据同步解调的原理,考察振动声调制检测输出信号中的调制成分,对金属杆内振动/超声在裂纹面上的相互作用进行了分析.制作了含有不同尺寸裂纹的铝杆试样,以扫频激励的方式得到合适的高频激励参数,分析输出信号中的调制信息,发现工件中的高频超声可分为两部分:一部分声波通过裂纹面,受到低频振动信号的调制,另一部分则保持不变。在此基础上对非线性调制模型进行了修正,并提出了一种用于裂纹检测的定量方法。与超声C扫描检测结果对比表明,此定量方法可用于估计金属杆中疲劳裂纹尺寸。

Interaction of fatigue crack with vibration and ultrasound in metallic rod and its use for quantitative characterization

According to the principle of synchronous demodulation, the modulation information in the output signal of vibro-acoustic modulation test was investigated and the nonlinear interaction of sound and vibration on the crack interface in a metallic rod was analyzed. A swept signal excitation was used to obtain a proper high frequency parameter in the test of aluminum rod samples with different size of crack, and the modulation information in the output signal was analyzed. It was found that the ultrasound wave in the structure can be separated into two parts. One is the wave which passes through the crack interface modulated by the low frequency vibration, and other wave has no any changes. The nonlinear modulation model was modified and a quantitative method for crack detection was proposed. It is demonstrated by comparing with the ultrasonic C-scanning that this method can be used to estimate the fatigue crack size in the metallic rod.