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首页> 外文学位 >Self-contained hybrid electro-hydraulic actuators using magnetostrictive and electrostrictive materials.
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Self-contained hybrid electro-hydraulic actuators using magnetostrictive and electrostrictive materials.

机译：使用磁致伸缩和电致伸缩材料的独立式混合电动液压执行器。

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Hybrid electro-hydraulic actuators using smart materials along with flow rectification have been widely reported in recent years. The basic operation of these actuators involves high frequency bidirectional operation of an active material that is converted into unidirectional fluid motion by a set of valves. While theoretically attractive, practical constraints limit the efficacy of the solid-fluid hybrid actuation approach. In particular, inertial loads, fluid viscosity and compressibility combine with loss mechanisms inherent in the active material to limit the effective bandwidth of the driving actuator and the total output power. A hybrid actuator was developed by using magnetostrictive TerFeNOL-D as the active driving element and hydraulic oil as the working fluid. Tests, both with and without an external load, were carried out to measure the unidirectional performance of the actuator at different pumping frequencies and operating conditions. The maximum no-load output velocity was 84 mm/s with a 51 mm long rod and 88 mm/s with a 102 mm long rod, both noted around 325 Hz pumping frequency, while the blocked force was close to 89 N. Dynamic tests were performed to analyze the axial vibration characteristics of the Terfenol-D rods and frequency responses of the magnetic circuits. A second prototype actuator employing the same actuation principle was then designed by using the electrostrictive material PMN-32%PT as the driving element. Tests were conducted to measure the actuator performance for varying electrical input conditions and fluid bias pressures. The peak output velocity obtained was 330 mm/s while the blocked force was 63 N. The maximum volume flow rate obtained with the PMN-based actuator was more than double that obtained from the Terfenol-D--based actuator.;Theoretical modeling of the dynamics of the coupled structural-hydraulic system is extremely complex and several models have been proposed earlier. At high pumping frequencies, the fluid inertia dominates the viscous effects and the problem becomes unsteady in nature. Due to high pressures inside the actuator and the presence of entrained air, compressibility of the hydraulic fluid is important. A new mathematical model of the hydraulic hybrid actuator was formulated in time-domain to show the basic operational principle under varying operating conditions and to capture the phenomena affecting system performance. Linear induced strain behavior was assumed to model the active material. Governing equations for the moving parts were obtained from force equilibrium considerations, while the coupled inertiacompliance of the fluid passages was represented by a lumped parameter approach to the transmission line model, giving rise to strongly coupled ordinary differential equations. Compressibility of the working fluid was incorporated by using the bulk modulus. The model was then validated using the measured performance of both the magnetostrictive and electrostrictive-based hybrid actuators.
机译：近年来，已经广泛报道了使用智能材料和整流功能的混合电动液压执行器。这些致动器的基本操作涉及活性材料的高频双向操作，该活性材料通过一组阀转换为单向流体运动。虽然理论上很有吸引力，但实际的限制限制了固液混合驱动方法的功效。特别是，惯性负载，流体粘度和可压缩性与活性材料固有的损耗机制相结合，以限制驱动执行器的有效带宽和总输出功率。通过使用磁致伸缩TerFeNOL-D作为主动驱动元件并使用液压油作为工作流体来开发混合执行器。进行了带有和不带有外部负载的测试，以测量在不同的泵送频率和工况下执行器的单向性能。最大的空载输出速度在51 mm长的杆上为84 mm / s，在102 mm长的杆上为88 mm / s，两者的泵浦频率均为325 Hz，而阻塞力接近89N。动态测试进行了分析，以分析Terfenol-D棒的轴向振动特性和磁路的频率响应。然后，通过使用电致伸缩材料PMN-32％PT作为驱动元件，设计了采用相同致动原理的第二个原型致动器。进行了测试，以测量在变化的电输入条件和流体偏置压力下的执行器性能。峰值输出速度为330 mm / s，阻塞力为63 N.使用基于PMN的执行器获得的最大体积流量是基于基于Terfenol-D的执行器获得的最大体积流量的两倍以上。结构-液压耦合系统的动力学极其复杂，并且较早提出了几种模型。在高泵浦频率下，流体惯性在粘性效应中占主导地位，问题在本质上变得不稳定。由于执行器内部的高压和夹带的空气的存在，液压油的可压缩性很重要。在时域中建立了液压混合执行器的新数学模型，以显示在不同工况下的基本工作原理，并捕获影响系统性能的现象。假设线性感应应变行为可以对活性材料进行建模。运动部件的控制方程是从力平衡的考虑中获得的，而流体通道的耦合惯性顺应性则是通过集总参数方法来表示传输线模型，从而产生了强耦合的常微分方程。通过使用体积模量来结合工作流体的可压缩性。然后使用基于磁致伸缩和基于电致伸缩的混合执行器的测量性能来验证该模型。

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