くし形電極を持つ圧電素子の表面に生ずるひずみ分布の 画像相関法による非接触計測と有限要素解析

抄録

In a piezoelectric element having interdigital transducers (IDT), strain distribution occurs depending on presence or absence of electrodes on the surface when a voltage is applied to the electrodes. Accordingly, it is important to understand the distribution and the mechanism of its generation. In this paper, a non-contact measurement method of the strain distribution by the Digital Image Correlation (DIC) using the IDT pattern is proposed, where speckle patterns are not necessary to be painted on its surface. The effectiveness of the proposed method is evaluated by comparing the strain obtained by the DIC to the strain measured by strain gauges and a finite element analysis (FEA) applying sinusoidal voltage to the electrodes. The results show that they are in good agreement in global strain over the element even though they are less than 100μ strain. The amplitude of the local strain on the electrodes are significantly different from those on the bare piezoelectric parts. The waveform of the DIC strain on the electrodes is asymmetric between applying the positive and the negative voltage and in antiphase to the bare piezoelectric parts. The reason of such a behavior is discussed by using the FEA result.