Hi
In the 2.15 example the polarization is opposite on top and bottom piezo patch (so the polarization is given by the material property definition TB command and the element system esys as shown below):
local,11 ! Coord. system for lower layer: polar axis +Y
local,12,,,,,180 ! Coord. system for upper layer: polar axis -Y
type,1 $ esys,11
amesh,1 ! Generate mesh within the lower layer
type,1 $ esys,12
amesh,3