2018 Volume 91 Issue 2 Pages 33-40
Piezoelectric materials have a property that they can convert the mechanical energy to the electric energy and vice versa, and making use of such property, they are used as sensors and actuators. The conventional piezoelectric materials which are piezoelectric ceramics are very hard and brittle, accordingly their application places are restricted. Instead of brittle piezoelectric ceramics, we have focused on flexible piezoelectric rubber for engineering use. At first, the “mixed-type” piezoelectric rubber was fabricated by mixing the rubber and piezoelectric ceramics particles with roll machine; however, its piezoelectricity was very low. Therefore, the “aligned-type” piezoelectric rubber which was aligned piezoelectric ceramics particles in rubber by applying voltage with rubber vulcanization was fabricated. The piezoelectricity of the aligned-type was higher than that of the mixed-type even though it has smaller amount of particles. In addition, it was confirmed that the increase of the force applied to aligning particles enhanced the piezoelectricity of the aligned-type. In this paper, we report the fabrication method and piezoelectricity of piezoelectric rubber, and also reported the result of applications of piezoelectric rubbers to a pinching sensor of foreign matter at the slide door of the rolling stock, and a damage detection sensor at the axle bearing of the rolling stock.
