A tensural displacement amplifier employing elliptic-arc flexure hinges

To increase the effective actuation stroke of piezoelectric stack actuators and giant magnetostrictive actuators, displacement amplifiers are usually employed to provide mechanical amplification. In this work, a novel symmetric two-stage lever-type amplifier called tensural displacement amplifier is proposed, in which all the flexural hinges are loaded in tension and bending rather than compression and bending when deflected. The tensural displacement amplifier does not have the potential problems buckling may cause because all the compliant members are loaded in tension. In addition, the proposed amplifier exhibits higher lateral frequency when deflected due to the stress stiffening effects of the tensural hinges. The kinetostatic model for the tensural displacement amplifier was established, based on which an amplifier whose amplification ratio exceeds 40 was designed. The amplification ratio of the design was further verified by the finite element model and prototype test.