Design Theory And Experiments Study Of Giant Magnetostrictive Pumps

As a new class of smart materials, Giant Magnetostrictive Material (GMM) has tremendous advantages of high strains, large output force, high energy density, fast response, and wide bandwidth, etc., leading to its wide application prospects in the fields of ultrasonic transducers, precision positioning, ultra-precision machining, micro motors, and active vibration control, etc. Currently, there is a growing demand in aviation and space aircraft for compact, light, and high-pressure hydraulic systems that can be distributed across the airframe with easy flow controls. Unfortunately, conventional hydraulic pumps cannot meet these needs. Therefore, it is significant but also necessary to develop novel hydraulic pumps and hydraulic systems based on novel smart materials. To provide theoretical supports and experimental data for further development of giant magnetostrictive pumps and hydraulic systems, research on structural optimum design, flow field analysis, system modeling and simulation, also experimental testing, were carried out in this dissertation.This dissertation analyzed the operational principle of existing hydraulic pumps and novel pumps based on smart materials. Mechanisms of magnetostrictive effect and the basic characteristics and their applications of GMM were also presented. Then, the state-of-art giant magnetostrictive pumps and the existing problems were described, explaining the significance of research on giant magnetostrictive pumps design and test.The overall design scheme of giant magnetostrictive pumps was proposed in this dissertation. Methodologies for actuation coil design and optimization were determined by analyzing the distribution of magnetic field intensity along the axes of GMM rod. The efficiency of electric-magnetic-mechanical conversion was improved by setting up equivalent magnetic circuits for the system. Moreover, with the application of Finite Element methods to simulation and analysis of the magnetic field of giant magnetostrictive pumps, the structure of magnetic loop was optimized, and the uniformity of magnetic fields was improved. Also, the influence on output performance caused by main parameters of preloading units, pumping chamber design, and one-way valve design was compared. On the basis of structural characteristics of giant magnetostrictive pumps, a novel sealing mode which combined static and dynamic sealing was designed. The2D and3D models for flow fields of giant magnetostrictive pumping chamber were established based on hydromechanical continuity equation and momentum equation. Simulation results indicated that the difference of chamber pressure increased with frequencies. Also, this dissertation analyzed the relationship between the loss of chamber pressure and the initial actuation speed of pistons under different chamber heights, described the distribution of pressure inside the pumping chamber, and discussed the causes of pressure loss. By analyzing the influence of the distributions, diameters, and chamfering shapes of inlet and outlet pipelines on pressure loss, the optimum design scheme was obtained, and parameters of the flow field structure were optimized. For one-way valve design, based on simulation results of flow velocity under different valve plate thickness using fluid-solid coupling, approaches for thickness selection and geometric structure optimization were proposed. In addition, laminar and turbulent conditions inside the pumping chamber as well as self-priming capability were also discussed.The experimental system of giant magnetostrictive pumps always involves sophisticated coupling of multiple physical fields. To understand the coupling among electrical, magnetic, mechanical, and flow fields, the relationship between the input characteristics and output flow rate, as well as the driving load velocity of hydrocylinder was investigated. Then, the static and state space based dynamic models of experimental system for giant magnetostrictive pumps were established by analysis and modeling of the GMM rod, piston, pump chamber, pipeline and hydrocylinder respectively. We conducted comparative analysis of the simulation results and experimental data finally.In this research, a prototype was designed and constructed, and an experimental system was established. We tested the output characteristics of giant magnetostrictive pumps, and discovered the relationship between output flow rate and pressure and input current and frequency. Moreover, the relationship between output velocity and input current under certain circumstances with and without loads was investigated. We discussed the influence of pre-load on the output performance of giant magnetostrictive pump and hydraulic system. Finally, causes and solutions of air bubbles in the system were discussed.