Dear Mehdi Baghaee, I hope this link helps you.

http://www.sciencedirect.com/science/article/pii/S1877705812045912

Dear Mohannad Husain Al-Sherrawi , your recommended paper did not help me. It uses solid elements to analyse the piezo-beams. Where I am looking for shell elements.

here what is appeared in the conclusion of that paper:

Two problems of piezoelectric analysis were solved using various finite elements and configuration in Ansys. The bimorph beam bending requires correct setting of piezoelectric stress matrix, so that the results were comparable to the simplified linear theory. The distribution of the electric potential in piezoelectric body was further investigated in a problem of short-circuited PZT cantilever beam. Model composed of two layers of quadratic elements or the linear elements with increased order of shape functions can be considered as sufficient for this problem.

Hi,

A four node shell element with piezoelectric coupling has been developed and implemented in ANSYS in this articel:

I hope it help you.

Article High-Performance 4Node Shell Element with Piezoelectric Coupling