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低阶水平剪切波具有的几个特点使得它特别适合应用于结构大范围无损检测。通过对换能器几何结构的设计,电磁声换能器能实现多种不同模态导波的激励,如板中的兰姆波和水平剪切波,但电磁声换能器的性能受其结构参数影响很大。为实现磁铁阵列式电磁声换能器的性能评价,开发一种用于换能器远场周向声场分布计算的线源分布模型,对具有不同几何参数的电磁声换能器的性能进行数值计算,如磁铁数量、磁铁周期、线圈的内外径等。这些参数对激励出的SHO波的指向性有很大影响,主要表现在主瓣及旁瓣的幅值及宽度方面。根据数值分析结果,为获得较好的指向性对换能器的结构参数进行优化设计。将优化设计研制出的换能器用于窄板结构无损检测,结果表明窄板的侧边界对SHO波的传播基本没有影响,可用于窄板结构的无损检测。提出可预测出磁铁阵列式电磁声换能器的声场分布并用于换能器参数优化的线源分布模型。
Several features of low-level horizontal shear waves make it particularly suitable for large-scale non-destructive testing of structures. Through the design of the transducer geometry, the electromagnetic sound transducer can realize the excitation of many different guided wave modes, such as the Lamb wave and the horizontal shear wave in the plate, but the performance of the electromagnetic sound transducer is affected by Structural parameters have a great influence. In order to realize the performance evaluation of the magnet array transducer, a linear source distribution model for the calculation of the acoustic field distribution in the far field of the transducer is developed. The performance of the electromagnetic transducer with different geometrical parameters is numerically Calculations, such as the number of magnets, the magnet cycle, the coil diameter and so on. These parameters have a great influence on the directivity of the excited SHO wave, mainly in the amplitude and width of the mainlobe and side lobes. According to the results of numerical analysis, the structural parameters of the transducer are optimized for obtaining better directivity. The optimized design of the transducer for the non-destructive testing of the narrow plate structure, the results show that the narrow side of the boundary of the SHO wave propagation has no effect, can be used for non-destructive testing of the narrow plate structure. Proposed the source distribution model can predict the sound field distribution of the magnet array electromagnetic transducer and used to optimize the transducer parameters.