Investigation on singular fields in piezoelectric joints and its application

Abstract

Singular stress and electric displacement fields occur at the vertex of interface in piezoelectric joints under an external loading. It can be expected that concentrated electric displacements causes large electric fields in an adjacent space and electric potential will be induced on the surface of electrode when the electrode approaches to the electric field. In the present paper, a piezoelectric joint which four blocks of piezoelectric material are bonded using a resin is analyzed. In this joint, a singular field occurs at a center gathering four vertexes in blocks and the intensity of singularity in electric displacements around the center of cross section in the joint may be four times larger. The intensity of singularity is numerically investigated using several methods for analysis to pursue the possibility of application of the singular fields. Firstly, three loading conditions, e.g., compression in the poling direction, compression in the vertical direction of side surface and input a voltage, are investigated for increasing a response of electric displacement in the piezoelectric joint. In the case of compression in the vertical direction of side surfaces, the maximum response is obtained. Hereafter, the results in the analyses are obtained for the compression of vertical direction of side surface. It is shown that the intensity of singularity depends on a power law of the thickness of adhesive layer. Influence of material properties of adhesive layer, piezoelectric and dielectric properties in the block of the joint, on singular fields is also investigated. It is shown that when piezoelectric materials with large piezoelectric constant are used, amplified electric displacements are obtained.