基于电磁超声兰姆波的铝合金板材小缺陷检测技术研究

摘要

Due to the advantage of being free couplant,electromagnetic ultrasonic technique has been widely utilized in the nondestructive testing and nondestructive evaluation fields.Based on the excitation principle of the lamb-wave electromagnetic a-coustic transducers ( EMATs) ,a 3-D finite element model was implemented to study the feasibility of the detection of small de-fects of aluminum plates by studying the interaction principle of Lamb wave with defects.Lamb-wave EMATs was designed to de-tect a small through hole with 1mm in diameter,served as a standard defect in GJB3384—98.A detecting device prototype with the transducers mentioned above was developed. Experiments show that the prototype can not only effectively detect the small throughhole,but also be capable of detecting a slot with length of 4mm and depth of 0.4 mm.The research lays a foundation for the industrial applications of the detection of small defects based on electromagnetic ultrasonic technology.%电磁超声技术因其无需耦合剂等优点而在无损检测与无损评估领域获得广泛应用。在分析铝合金板材中电磁超声兰姆波激发原理的基础上，结合兰姆波与缺陷的作用机理，建立了电磁超声兰姆波三维有限元声场模型，分析了利用电磁超声换能器检测铝合金板材小缺陷的可行性。针对GJB3384—98的检测要求，设计了可用于检测直径为1 mm的小型通孔缺陷的电磁超声兰姆波换能器。在此基础上研制了基于电磁超声兰姆波技术的铝合金板材检测样机。实验表明，该样机不仅能够有效检测出GJB3384—98规定的小型通孔，也能检测出长度为4 mm、槽深为0.4 mm的槽型缺陷，为基于电磁超声技术的铝合金板材小缺陷检测的工程应用奠定了基础。