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目的:超声导波是一种有潜力的无损检测方法,磁致伸缩换能器是一种重要的导波换能器。利用经典的简正模态展开法分析弹性空心圆柱体在磁致伸缩载荷下的激励响应,包括磁致伸缩局部载荷、轴向阵列载荷和圆周阵列载荷。空心圆柱体在磁致伸缩载荷作用下的扰动分析将为磁致伸缩换能器以及换能器阵的进一步发展提供理论依据。创新点:1.利用简正模态展开方法,讨论弹性空心圆柱体在磁致伸缩载荷作用下的扰动分析和激励响应;2.通过数值仿真和试验研究,验证空心圆柱体在磁致伸缩局部载荷、轴向阵列载荷和圆周阵列载荷作用下不同的激励响应,得到有效的结论。方法:1.通过理论推导,构建典型磁致伸缩换能器数学模型(公式(15)和(17));2.通过理论推导,建立弹性空心圆柱体在磁致伸缩局部载荷、轴向阵列载荷和圆周阵列载荷作用下的波源分析模型(公式(25~26)、(30~31)和(34~35)),求解得到典型载荷形式下的激励响应(图6~8和11~13);3.通过仿真模拟和试验研究,对空心圆柱体在不同磁致伸缩载荷作用下的激励响应进行验证(图14~21)。结论:1.磁致伸缩局部载荷能够激励产生同一族的导波模态,但是不具有良好的频率选择性和相速度选择性,轴对称载荷仅能激励轴对称模态;2.磁致伸缩轴向阵列载荷具有良好的频率选择性和相速度选择性,中心频率和中心相速度取决于阵列单元间距,对导波模态控制非常有益;3.磁致伸缩圆周阵列载荷能够激励周向阶次为阵列单元数整数倍的导波模态。
OBJECTIVE: Ultrasonic guided wave is a potential nondestructive testing method. Magnetostrictive transducer is an important guided wave transducer. The excitation response of the elastic hollow cylinder under magnetostrictive load is analyzed by classical normal mode expansion method, including local magnetostrictive loads, axial array loads and circumferential array loads. The perturbation analysis of the hollow cylinder under the magnetostrictive load will provide a theoretical basis for the further development of the magnetostrictive transducer and the transducer array. Innovative points: 1. Using the method of normal mode expansion to discuss the perturbation analysis and the excitation response of the elastic hollow cylinder under the magnetostrictive load; 2. Through the numerical simulation and experimental study, Axial array load and circular array load under different excitation response, get effective conclusion. (1) The mathematical models of typical magnetostrictive transducers are constructed by theoretical derivation (formulas (15) and (17)); 2. By the theoretical derivation, the elastic hollow cylinders are established in the field of magnetostrictive local loads, (25 ~ 26), (30 ~ 31) and (34 ~ 35) under the load and circumferential array loads, the excitation response under typical load is obtained (Figs.6-8 and 11-13 ); 3. Through the simulation and experimental study, the excitation response of the hollow cylinder under different magnetostrictive loads was verified (Figure 14-21). Conclusion: 1. Magnetostrictive local loads can stimulate the generation of the same waveguide wave mode, but does not have good frequency selectivity and phase velocity selectivity, axial symmetric load can only stimulate the axisymmetric mode; 2. Magnetostrictive Axial array loads have good frequency selectivity and phase velocity selectivity. The center frequency and center phase velocity depend on the array element spacing, which is very beneficial to guided mode control.3. Magnetostrictive circular array loads can stimulate the circumferential order to Waveform of integral multiple of array element.