Non-resonant piezoelectric actuator with large displacement at low frequencies

A novel piezoelectric actuator is proposed to enhance its displacement in broad band at low frequencies. Its structure consists of a tunable stiffness part and a driven part. The tunable stiffness part is the piezoelectric stacks shunted with negative capacitance and its effective stiffness could be softening widely under the proper capacitance ratios at low frequencies. The principle of tunable stiffness system is analyzed and the proposed actuator is simulated by multi-physics coupled finite element method. When negative capacitance is selected properly, the displacement of the actuator can be increased up about 10 to 100 times in much broad band even at non-resonant low frequencies. The non-resonant actuator can be used to generate large displacement at low frequencies.