基于准三维超声成像的电阻点焊定量检测技术研究

Quantitative detection technology of resistance spot welding based on quasi three-dimensional ultrasonic imaging

针对利用传统超声C扫成像方法对电阻点焊定量检测时图像对比度分辨率低的问题,对超声波在被测构件中传播时表现出的衰减特性进行了研究,分析了电阻点焊超声信号的特征,测定了超声检测信号在被测工件中的衰减系数,提出了一种准三维电阻点焊超声成像方法。该方法基于小波多子带差异性补偿算法,同时对超声波传播的距离和频率进行了补偿,在减小超声波衰减的同时也提高了电阻点焊超声图像的对比度分辨率。利用该方法开展了电阻点焊相关参数的定量化检测研究,并进行了相关的实验验证。研究结果表明,该技术有效提高了电阻点焊超声成像的对比度分辨率,可以避免图像中目标检测对象与背景的融合现象,提高了电阻点焊参数的定量化检测能力,并可将检测结果友好表征。

Aiming at the problem of low-contrast resolution of the conventional ultrasonic C-scan imaging for resistance spot welding quantitative detection,the attenuation characteristics of ultrasonic wave propagation in the tested structure were studied. The characteristics of resistance spot welding ultrasonic signals were analyzed,the attenuation coefficient of ultrasonic signals in the workpiece was measured,and a quasi three-dimensional resistance spot welding ultrasound imaging method based on wavelet multi-sub-band difference compensation algorithm was proposed. The frequency and distance attenuation of ultrasonic propagation was compensated simultaneously,the attenuation was reduced and the contrast resolution of resistance spot welding ultrasound image was increased. This method was applied into the study of quantitative detection for resistance spot welding parameters and verified in related experiments. The results indicate that the contrast resolution of resistance spot welding ultrasound imaging is increased effectively,the phenomenon of target object image fusion in background is avoided,and the capability of resistance spot welding parameters quantitative detection and test results characterization are improved.