Piezoelectric behavior of pre-stressed curved actuators under load

Pre-stressed curved actuators typically consist of a piezoelectric ceramic (lead zirconate titanate or PZT) laminated between various layered materials. In one configuration, THUNDER, the bottom layer is stainless steel and the top layer is aluminum; the metallic layers are attached to the PZT ceramic using a polymeric adhesive. In another configuration, Lipca-C2, the layers comprise a glass/epoxy composite and a carbon/epoxy composite. Experimental and numerical results of displacement performance under unloaded conditions have been investigated in the past. The results show that the Lipca-C2 devices produced more displacement than the THUNDER devices when clamped and unloaded. The present study includes a comparative performance of both devices under load to evaluate their lifting capability. Both out-of-plane and in-plane displacements are assessed as a function of load and voltage at low frequency. A non-contact laser was used for the out-of-plane measurements simultaneously with an optic fiber for in-plane displacement at 0 to 5N load values. The load is attached to one end of the actuators, and to avoid possible damage to the actuators, it is moved through a mechanism that utilizes a frictionless linear bearing and a pulley.