脉冲交变磁场测量技术缺陷识别与定量评估

Pulsed Alternating Current Field Measurement Technique for Defect Identification and Quantification

传统的交变磁场测量(Alternating current field measurement,ACFM)技术具有缺陷定量准确、无需接触等优点,但是不能检测深层缺陷;脉冲涡流检测技术(Pulsed eddy current testing,PECT)具有较好的深层缺陷检测能力,但由于采用瞬态响应信号分析方法,容易受到提离效应干扰,工程实际应用较为困难,并且定量能力弱于ACFM技术。结合ACFM和PECT的优势,提出了脉冲交变磁场测量技术(Pulsed alternating current field measurement,PACFM)。该技术采用脉冲周期信号作为激励信号源,基于瞬态脉冲响应信号,采用三维场量测量和瞬态信号分析相结合的方法实现缺陷识别与定量评估。对瞬态响应信号中能够表征磁场变化规律的特征量进行提取,通过研究发现PACFM不仅具有与ACFM等同的表面缺陷检测能力,而且具有优异的深层缺陷识别与定量评估能力,抗干扰能力强,具有较高的应用价值和前景。

Traditional alternating current field measurement（ACFM） technique has advantages of quantitative defect detection and noncontact,but poor detective performances on deep-layer defects.Pulsed eddy current testing（PECT） has a better detectability in deep-layer defect,but poorer quantitative performances than ACFM,and moreover,it is easily interfered by lift-off due to using transient response signal analysis method so it is difficult to be applied practically.A method of alternating current filed measurement with pulsed signal excitation is proposed,which implements defect detection and quantitative evaluation by approach of transient signal analysis combined with 3D magnetic filed measurement based on pulsed response signal.Characteristics in the transient response signal which can reflect the variation law of magnetic field are extracted.Through the study it is found that the pulsed alternating current field measurement has not only the same detectability of surface defects as ACFM,but also an excellent capability of deep defect identification and quantitative evaluation.