摘要
本文采用电磁声传感器接收单一S0模态激励,测量Lamb波在板中不同深度的槽形裂纹处的反射与透射,用于对已知扩展长度的表面裂纹进行深度测量。然后分析了Lamb波模态的频散与波动特性,由超声Lamb波的波结构,近似计算了S0模态入射到裂纹时的反射系数。计算结果与实验结果一致。结果表明,Lamb波在有限长裂纹处的反射系数可采用二维模型中的反射系数求解公式近似求解。采用电磁超声传感器接收单一S0模态激励,重复测量稳定性高,适用于Lamb波反射系数的测量。Lamb波的反射系数与裂纹深度有很好的对应关系,可用于板表面已知长度裂纹的深度测量。
Electromagnitic acoustic tranducers （EMAT） were adopted to receive single So mode exitation. The reflection and transmission of Lamb wave in a plate were measured at slotted cracks with different depths, which was used for depth measurement of surface crack with known extended length. The modal dispersion characteristics and fluctuation properties of Lamb wave was analyzed. The reflection coefficient of incident So mode on the crack was approximately calculated, based on the structure of ultrasonic Lamb wave. The calculated results are consistent with experimental ones. Results show that the reflection coefficient of Lamb wave at carck with finite length can be approximately solved by using two--dimensioanal model reflection coefficient solving formula. EMAT provides high stability in repeated measurements and is suitable for measurement of Lamb wave reflection coefficient There is a good corresponding relation between the crack depth and Lamb wave reflection coefficient, which can be used for depth measurement for plate surface crack with known length.
出处
《实验力学》
CSCD
北大核心
2013年第5期649-656,共8页
Journal of Experimental Mechanics
基金
国家科技支撑计划(2011BAK06B03)资助
关键词
LAMB波
电磁声传感器
裂纹
无损检测
反射系数
透射系数
Lamb wave
EMAT
crack
non-destructive testing
reflection coefficient
transmission coefficient
