【摘要】 以AZ91铸造镁合金试块上的人工孔形缺陷为检测对象,研究缺陷的直径及埋藏深度与超声A扫描信号特征量的关系。结果表明,缺陷信号幅值与孔形缺陷直径及其埋藏深度有良好的线性关系。采用低通滤波和小波分析的方法对从镁合金试块上采集到的弱信号进行降噪处理,结果表明,小波变换能有效提高小孔径缺陷信号的信噪比。更多还原

【Abstract】 AZ91 cast magnesium alloy with artificial defects in shape of hole were investigated to relate with the ultrasonic A signal and its characteristic value. The results indicated that there existed a good linear relation between the A signal amplitude and the diameter and position of the holes. Also, the research adopted low pass filter and wavelet analysis to decrease the noise, and the results indicated that using wavelet analysis the signal to noise ration could be effectively raised for the ultrasonic A signal of small holes.更多还原