Performance Modeling of a Piezohydraulic Actuator with Active Valves

Piezohydraulic actuation is the use of hydraulic fluid to rectify the high frequency, small stroke oscillation movement of the piezoceramic stack into a unidirectional movement. This paper presents a quasi-steady incompressible flow model and a compressible flow model for performance simulation. These two models are derived based on the energy equations for hydraulic flow in circular pipe. Major losses and minor losses are identified and incorporated in the model. Assumptions and approximations were made to minimize computation effort while achieving good accuracy. A piezohydraulic actuation system with active valves is then built and tested. Comparison with test results shows that the simulations accurately predict system performance under loads at which value leakage is not present. The results reveal that friction losses due to viscosity are a major limitation of performance for the current test setup when operating at higher frequencies.