Electro-elastic analysis of a coated spherical piezoceramic sensor

Nowadays, piezoceramics are widely used in sensor technology. However, due to their brittle nature, they can be cracked either in severe environmental conditions or during careless installation. Besides, the abrasion of their surface is a challenging problem in some applications. Hereby, the usage of a protective layer can prolong their effective working life. In this study, we analyze the electro-elastic behavior of a spherical piezoceramic sensor coated by a homogeneous protective layer. Then, with the motivation of reducing possible interfacial problems across the sensor/coating interface, and also improving the sensing ability of the coated sensor, material gradation concept is utilized. For this intent, two sensor/coating systems are studied: a piezoelectric sensor coated with a functionally graded material, and a functionally graded piezoelectric sensor coated with a homogeneous material. The governing equations are derived within the context of electro-elasticity theory and closed-form solutions are presented for coated sensors. It is concluded that a piezoceramic sensor protected with a functionally graded coating can improve the interfacial condition of the coated sensor, as well as enhancing its sensing ability.