中文摘要：

Lamb波具有传播距离远、衰减小等优点,能在板结构中实现大范围、高效率的损伤检测和监测,在无损检测和结构健康监测领域具有极大的应用潜力。针对板结构大范围健康监测问题,为了能周向一致地激励出模态单一Lamb波S0模态,提高缺陷成像能力,基于磁致伸缩效应,设计并制作一种全向型S0模态磁致伸缩传感器,由印刷电路板线圈,圆柱磁铁,圆形镍片组成。试验验证研制的传感器能够在铝板中有效激励出单一的S0模态,并测试其频率响应特性以及全向性,结果表明设计传感器中心频率为365 k Hz,并具有较好的全向性。进一步利用研制的全向型S0模态磁致伸缩型传感器组成稀疏传感器阵列。采用自激自收的方式对铝板结构中缺陷进行检测。利用离散圆弧成像与数据融合算法相结合的方法对多组数据进行处理,消除常规的稀疏传感器阵列成像时对结构健康状况下的信号依赖,无需健康状况下的信号作为参考,实现了在板结构中缺陷的定位和成像。

英文摘要：

Lamb waves can achieve defect detection and monitoring with large scale and high efficiency in plate-like structures because of its advantages including long propagation ability and low attenuation. Thus, Lamb wave technology has immense application potential in nondestructive testing and structural health monitoring. Aiming at consistently exciting single Lamb wave, S0 mode, in circumferential direction and improving imaging ability for the wide range health monitoring of plate-like structure, an omni-directional S0 mode magnetostrictive transducer is developed on basis of magnetostrictive effect and it consists of a coil on PCB, a cylindrical magnet and a circular nickel patch. The experimental results firstly verify that this type of transducer can effectively produce the pure S0 mode in an aluminum plate. Then, the frequency response characteristics and omni-directivity of this developed transducer are tested. The results demonstrate that developed transducer has a center frequency of 365 k Hz and high omnidirectional consistency. Furthermore, a distributed sparse transducers array is built by using developed omni-directional S0 mode magnetostrictive transducers. An aluminum plate is detected in pulse-echo mode by using this transducer array. The combination of discrete arc imaging and data fusion algorithm is used to deal with multiple sets of data, which eliminates the dependence upon the signals in health condition compared with the conventional sparse transducers array imaging algorithms. The location and imaging of the defect could be well achieved without the need of reference signals in health condition.