【摘要】 针对电磁超声换能器EMAT(Electromagnetic Acoustic Transducer)换能效率较低的问题,以铝板为研究对象,对传统的表面波电磁超声换能器进行了有限元建模及参数优化。分析了激励EMAT的换能机理,建立曲折线圈EMAT检测过程的有限元模型,并基于正交试验设计方法进行优化设计,分析了永磁体尺寸、线圈设计参数、线圈层数及层间距、线圈连接方式等因素对EMAT激励效率的影响规律,得到了激励EMAT探头的最佳参数组合。研究结果表明,永磁体高度越高,宽度越窄,曲折线圈导线宽度越窄,导线高度越低,双层线圈间距越小,背板与上层线圈间距越小,并采用分裂线圈,EMAT探头的换能效率最高;多层曲折线圈之间采用并联连接相比串联连接换能效率提高50%以上,且并联曲折线圈层数不宜过多也不宜过少。更多还原

【Abstract】 Aiming at the low efficiency of electromagnetic acoustic transducer(EMAT),the finite element modeling and parameter optimization of the traditional surface wave electromagnetic transducer were carried out with aluminum plate as the research object. The energy transfer mechanism of exciting EMAT is analyzed,and the finite element model of the detection process of EMAT with tortuous coils is established. Based on the orthogonal test design method,the optimum design is carried out. The influences of the size of permanent magnet,the design parameters of coils,the number and spacing of coils and the connection mode of coils on the excitation efficiency of EMAT are analyzed,and the optimum combination of parameters for exciting EMAT probes is obtained. The results show that the higher the height of permanent magnet is,the narrower the width of meander coil is,the lower the height of meander coil is,the smaller the distance between double coils,the smaller the distance between backplane and upper coils,and the EMAT probe has the highest energy conversion efficiency by using split coils;the energy conversion efficiency of parallel connection between multi-layer meander coils is more than 50% higher than that of series connection,and the layer of parallel meander coil is more than that of series connection. The number of parallel meander coil layers should not be too much or too small.更多还原