Development of a resonant piezohydraulic hybrid actuator.

This paper proposes a piezohydraulic hybrid actuator driven by a resonant vibrator based on two rhombic micro-displacement amplifiers. The resonant piezohydraulic hybrid actuator consists of a resonant piezoelectric vibrator, a pump body, a manifold, a return valve, and an output cylinder. The vibration mode of the piezoelectric vibrator is simulated, and the working principle of the resonant piezohydraulic hybrid actuator is depicted. Then, the performance of the piezohydraulic hybrid actuator is experimentally investigated, and the effects of exciting frequency, exciting voltage, and bias pressure are analyzed. The results demonstrate that the hybrid actuator performs the best when the exciting frequency is near the resonant frequency; meanwhile, the higher the exciting voltage, the better the performance. Moreover, it indicates that a larger bias pressure will bring a larger reaction force to the vibrator and reduce the performance of the actuator system. The maximum blocked force and no-load velocity are 378 N and 4.8 mm/s, respectively, when the bias pressure is 1.5 MPa and the exciting voltage is 500 Vpp.

High-speed giant magnetostrictive actuator using laminated silicon steel core.

The high-frequency eddy current loss limits the output speed of the giant magnetostrictive actuator (GMA). This paper investigates a GMA using a laminated silicon steel core. Compared with the integral silicon steel core, the laminated silicon steel core can reduce the equivalent conductivity and eddy currents. The laminated structure reduces the magnetic reluctance of the core and increases the magnetic field intensity in the giant magnetostrictive material rod. Therefore, the actuator can output large vibration amplitude under high-frequency magnetic field. At the sinusoidal excitation current of 35 A (rms) @ 2 kHz, the output vibration amplitude of the actuator using the laminated silicon steel core is 11.1 µm @ 4 kHz, which is 44.2% higher than that of the actuator with the integral silicon steel core. This indicates that the laminated structure of the magnetic core is beneficial to improve the output speed of GMA.