中文摘要：

研究传感器布置对导波沿薄壁金属管道的频散特性、模态转换和缺陷定位的影响规律。其步骤为：首先,采用ANSYS软件建立薄壁小直径的无缺陷管道和缺陷管道有限元模型;采用瞬态动力学分析方法,对管道端部周向各节点施加轴向瞬时位移载荷,模拟超声传感器激发L（0,2）模态波;根据脉冲-回波信号的时间历程曲线,定义回波分辨率、反射系数。其次,分析缺陷的轴向位置精度以及4种传感器布置方案对导波频散、模态转换、周向定位和反射系数的影响。研究结果表明：增加传感器数量可有效抑制弯曲模态和导波频散的发生,并增强回波信号的幅值;当传感器数量小于4个时,难以对裂纹缺陷进行周向定位;反射系数随传感器数量的增加呈线性增大。

英文摘要：

The influence of sensor distribution scheme on the frequency dispersion characteristics, modal conversion and defect localization of guided wave along thin-walled metal pipe was investigated. The procedures were as follows. Firstly, the models of defective and non-defective finite element pipes were built using ANSYS software. Axial displacement was exerted to circumferential nodes in the end of pipe based on the transient dynamic analysis methods, and ultrasonic sensor activating L（0,2） mode was simulated. Then, according to time-history curves of the pulse-echo, characteristic parameters such as echo resolution and reflection coefficient were defined. Secondly, the axial defect location precision, as well as the influence of four sensor distribution schemes on the guided wave dispersion, modal conversion, circumferential localization and reflection coefficient were analyzed. The results show that bending modal and wave dispersion can be inhibited effectively while amplitude of echo signal can be amplified by adding sensors. It is difficult to locate crack defects circumferentially when the number of sensors is less than 4.And the reflection coefficient increases linearly with the increase of the number of sensors.