摘要
针对板结构大范围健康检测问题,进行了周向一致兰姆波电磁超声换能器研制。基于电磁超声检测原理,建立板中周向一致兰姆波EMAT的理论模型,推导出换能器接收电压及等效灵敏度表达式。基于换能器结构参数与等效灵敏度关系,设计制作了7种类型的周向一致电磁兰姆波换能器,并进行了换能器阻抗匹配设计。通过实验和理论分析表明,设计的EMAT能有效激励单一模态S0兰姆波,对特定波长的兰姆波具有选择性,且其实测换能器中心频率与设计值能很好吻合。同时,在同一频率下,实验测得不同内外径比的换能器其灵敏度分布与理论曲线能很好吻合。检测实验证明,设计的换能器能在其周围360°方向具有很好的一致性,为后续板结构换能器阵列奠定了基础。
Aiming at wide range health monitoring of plate structure,an omni-directional Lamb wave electromagnetic acoustic transducer（EMAT） was developed.Based on the theory of electromagnetic acoustic testing,the model of omni-directional Lamb wave EMAT for plate was established,and the expressions of received signal and equivalent sensitivity were obtained.Considering the relationship between structural parameters of EMAT and its equivalent sensitivity,seven omni-directional EMATs were fabricated,and their impedance matching was conducted.Experiment and theoretical analysis show that the designed EMAT can excite single S0 mode Lamb wave effectively and has selectivity to the lamb wave with given wavelength,and the tested center frequency agrees well with the designed value.Meanwhile,the measured sensitivities of EMATs with different ratios of inner and outer diameters are consistent well with the theoretical curves at same frequency.Experiment results prove that the designed EMATs have good consistency in the direction of 360°,which establishes a good foundation for the development of subsequent transducer array for plate structure monitoring.
出处
《仪器仪表学报》
EI
CAS
CSCD
北大核心
2010年第6期1387-1393,共7页
Chinese Journal of Scientific Instrument
基金
国家自然科学基金(10772008)
863计划(2008AA042207)
北京市科技新星项目(2007B012)
北京市教委(KM200810005009
KZ200810005001)资助项目
关键词
兰姆波
电磁超声换能器
无损检测
周向一致
模态选择性
Lamb wave
EMAT
non-destructive testing
omni-directional consistency
modal selectivity
