利用激光超声技术研究表面微裂纹缺陷材料的低通滤波效应  

Low pass effect of surface defect metal based on laser ultrasonic

作　　者：王敬时[1] 徐晓东[1] 刘晓峻[1] 许钢灿[2] 

机构地区：[1]南京大学声学研究所,近代声学教育部重点实验室,南京210093 [2]杭州应用声学研究所,杭州310012

出　　处：《物理学报》2008年第12期7765-7769,共5页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10674069,10574071)资助的课题~~

摘　　要：利用激光激发声表面波的理论模型,研究了被激发宽带声表面波在具有表面微裂纹缺陷金属材料上的传播特性.对具有不同形状的表面缺陷模型进行了数值分析.结果表明:表面微裂纹缺陷有明显的低通效应,缺陷深度越大高频截止频率就越低,缺陷深度与低通滤波的截止频率呈近似线性关系;缺陷的宽度增大对表面波透射能量有明显的衰减作用.The travelling properties of laser-generated surface acoustic wave with broad bandwidth, which propagated on a sample with surface defects, have been investigated in theory. The numerical results of theoretical models with different defects indicate that the surface defects worked as low-pass filter for the travelling surface acoustic waves. The cut-off frequency of low-pass filter is linearly related to the depth of the defect, and decreased against the increasing depth of the defect. The amplitude of the travelling surface acoustic wave is seriously attenuated with increasing width of surface defect. The numerical results provide a theoretical basis for quantitative detection of the surface defects.

关 键 词：激光超声 声表面波 有限元方法 低通滤波器 

分 类 号：TH878[机械工程—仪器科学与技术]