Study for multilayer piezoelectric composite structure as displacement actuator by Moiré interferometry and infrared thermography experiments

Multilayer piezoelectric structures are widely applied as a smart structure in precise apparatus. When the structure is in service, fractures often occur near the internal electrode layers. To analyze this issue, a multilayer piezoceramic structure used as displacement actuator is investigated both experimentally and numerically in this paper. Through Moiré interferometry experiment, the plane displacement distribution of the structure is obtained, which is holistically consistent with and locally more acute than the one obtained from finite element simulation. This displacement field shows there is considerable non-uniform deformation in the structure, which is caused by electric field concentration near the edge of the internal electrode, and consequently induces serious stress concentration there that may finally lead to significant damage or failure of the structure in its working environment. Furthermore, the thermal phenomena in piezoelectric structures were measured experimentally by applying infrared thermography. The thermo-concentration around interface crack and inside internal microdefects may intensify non-uniform stress distribution and make structure more vulnerable in its working environment. Hence it should be taken into account in the investigation of piezoelectric structures henceforth.