Design And Experimental Research On Deep-sea Resonant Linear Piezoelectric Actuators

The ocean gradually becoming an significant object of scientific research for the rich mineral and biological resources. However, strictly demands in environmental adaptability and reliability of deep-sea actuators are required as a result of the extremely severe deep-sea environment. Pressure balance scheme is employed by most of the existing deepwater motors and the deepwater hydraulic systems, which increased the parts number, volume and weight and lower the reliability. Resonant piezoelectric actuators using the inverse piezoelectric effect of piezoelectric materials to convert the electrical energy into mechanical energy, which bring it a great number of advantages which includes simpler structure, more flexible design, lower speed with higher torque(thrust), higher power density, higher positioning accuracy, faster response speed, etc.This paper served the resonant piezoelectric actuators to the deep sea in open status; assembling directly on function mechanism instead of overall pressure isolated seal, linear action driven by electricity, sealing the electrical interface section simply to substitute for pressure tank, dynamic seal part, pressure balance link and the transmission mechanism; improved power-to-weight ratio, compact structure, environment adaptability and reliability comparing with the existing deep-sea motors.In this paper, a single mode linear piezoelectric actuator was designed by using the expansion mode of the flat plate and the asymmetric excitation. The driving principle of this kind of vibration mode was analyzed, and the equivalent electrical model of piezoelectric vibrator was established. The structure optimization design of piezoelectric vibrator was carried out by the finite element method. Three kind of the finite element modal of unencapsulated, encapsulated, immersed in water were established and they were calculated by modal analysis and transient analysis. And he effect on the vibration characteristics of the encapsulation adhesive layer and water for piezoelectric vibrator were investigated.Piezoelectric actuator overall structure were designed and manufactured. Then a deep-sea high pressure environment simulation system was designed to carry out underwater pressure test. Some piezoelectric actuators were respectively unencapsulated, encapsulated, immersed in water. And the impedance characteristics of these piezoelectric actuators were test by impedance analyzer.And then the electromechanical coupling characteristics of piezoelectric were studied. The final experimental scheme in air and water of the piezoelectric actuator mechanical properties were designed and tested.