Experimental study of axial-compressed macro-fiber composite bimorph with multi-layer parallel actuators for large deformation actuation

Piezoelectric bimorphs have a promising application in morphing micro air vehicles; however, increasing the actuation displacement is a difficult point. Axial compression can be used to increase the deformation of the piezoelectric bimorph. Compared with piezoelectric ceramics, macro fiber composites offer higher flexibility. In this article, a large displacement actuator of axial-compressed macro fiber composite bimorph is proposed. A multi-layer parallel scheme of macro fiber composite bimorphs is presented to increase the output torque of piezoelectric bimorph within a limited space. The actuation performance of the axial-compressed macro fiber composite bimorph and its multi-layer parallel scheme are verified through quasi-static experiment and displacement tracking control test. The experimental results show that the end-free rotations of both the axial-compressed macro fiber composite bimorph and its multi-layer scheme achieve ±8.1°, which is 60% higher than that of a piezoelectric ceramics bimorph with the same length. The blocking torque of the single-layer macro fiber composite bimorph is 0.028 Nm. The proposed parallel bimorphs method can magnify output torques. In addition, the axial-compressed macro fiber composite bimorph can accurately track any displacement signals in the range of its actuation. It is a continuous and controllable piezoelectric bimorph with large displacement.