基于压电增益特性进行梁中缺陷的识别

RESEARCH ON CRACK DETECTION OF FREE-FREE BEAM BASED ON PIEZOELECTRIC GAIN

驱动元件PZT片和传感元件PVDF膜粘贴于自由梁表面 ,通过测试压电增益 ,试验获取梁中不同缺陷尺寸下的固有频率。根据固有频率的变化 ,实现缺陷的识别。梁中的缺陷采用等效线性弹簧模拟 ,描绘出不同模态下刚度与缺陷可能位置曲线。根据曲线的交点 ,得出缺陷位置与尺寸。相比于实际的缺陷位置与尺寸 。

A theoretical and experimental analysis of piezoelectric gain to obtain the natural frequencies in a free-free beam is presented. Based on the change of natural frequencies of the cracked beam, the crack location and size are detected. The crack in the beam is modeled as an equivalent linear spring. The curves of relative stiffness with crack possible location are plotted for the first four natural modes. Considering the assumption that the crack relative stiffness is independent to the frequencies, the intersection of the curves gives the crack location. The crack size is then computed using the standard relation between stiffness and crack size. Compared to the actual for several cases, the maximum errors of crack location and size are 4%, 9.3% respectively.