Electro-thermo-mechanical creep and time-dependent behavior of FGPM spheres

Piezoelectric materials exhibit significant creep effects even at room temperature. History of stresses and electric potential of thick-walled spheres made of functionally graded piezoelectric material (FGPM) subjected to an internal pressure and a distributed temperature was investigated. A semi-analytical method in conjunction with the method of successive approximation was developed. A major redistribution for electric potential was found to take place throughout the thickness, which changes with time in the same direction as the compressive radial stress. The results of this investigation can be used to improve the accuracy and reliability of smart structures used for high-precision applications.