压电智能梁的阻抗分析与损伤识别

IMPEDANCE ANALYSIS AND DAMAGE DETECTION ON PIEZOELECTRIC SMART BEAM

压电陶瓷具有正、逆压电效应,可以用作自驱动传感器.该文对表面粘贴有单片压电陶瓷的压电智能钢梁进行了阻抗分析.讨论了单压电片驱动下钢梁的纵向振动和弯曲振动,得到了压电智能梁的机械阻抗.介绍了压电片与基梁的机电耦合作用及基于压电阻抗技术的结构损伤识别机理.以两端自由钢梁为例对压电智能梁的压电阻抗进行了数值与实验验证,结果表明数值计算结果与实验结果基本相符.利用压电阻抗技术对两端自由的裂纹钢梁进行了损伤识别实验研究,实验结果发现,裂纹的出现引起高频段压电阻抗实部和虚部曲线出现了明显的变化;随着裂纹尺寸的增大,曲线谐振频率和反谐振频率逐渐减小.由此可见,通过测量钢梁损伤前后压电陶瓷片的电阻抗变化能够识别梁中的裂纹损伤.

Piezoelectric ceramic （PZT） can be used as a self-actuating sensor for its direct and converse electromechanical properties. Impedance analysis of a piezoelectric smart beam with a single PZT sheet attached to is implemented in this paper. The axial and flexural vibration analyses of the host beam actuated by the PZT sheet are presented,and the mechanical impedance of the piezoelectric smart beam is deduced. The coupling process between the PZT sheet and the host beam and the basic idea to damage detection based on piezoelectric impedance are also introduced. Subsequently, as an example, the piezoelectric imped- ance of a smart steel beam with free boundary conditions at both ends of the beam is verified numerically and experimentally, and the numerical and experimental results are comparable by and large. Finally, an ex- perimental study on damage identification of cracked steel beam is performed based on the piezoelectric impedance technique. It is found from the experimental results that and the presence of crack damage induces the visible change in the real and imaginary parts of the piezoelectric impedance at higher frequency ranges, and the resonant and anti-resonant frequencies decrease by the increase of the size of the crack. Therefore, it is concluded that crack damage of steel beams can be identified by monitoring the variations of piezoelectric impedance measurements.