The Load Capability of Piezoelectric Single Crystal Actuators
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The Load Capability of Piezoelectric Single Crystal Actuators Tian-Bing Xu1, Ji Su2, Xiaoning Jiang3, Paul W. Rehrig3, and Wesley S. Hackenberger3 1
National Institute of Aerospace, 144 Research Drive, Hampton, VA 23666, USA NASA Langley Research Center, Hampton, VA 23681, USA 3 TRS Technologies, Inc., 2820 East College Avenue, State College, PA 16801, USA 2
ABSTRACT Piezoelectric lead magnesium niobate-lead titanate (PMN-PT) single crystal is one of the most promising materials for electromechanical device applications due to its high electrical field induced strain and high electromechanical coupling factor. PMN-PT single crystal-based multilayer stack actuators and multilayer stack-based flextensional actuators have exhibited high stroke and high displacement-voltage ratios. The actuation capabilities of these two actuators were evaluated using a newly developed method based upon a laser vibrometer system under various loading conditions. The measured displacements as a function of mechanical loads at different driving voltages indicate that the displacement response of the actuators is approximately constant under broad ranges of mechanical load. The load capabilities of these PMN-PT single crystal-based actuators and the advantages of the capability for applications will be discussed. 1. INTRODUCTION Electromechanical actuators with large stroke, high precision, and high mechanical load capability are important for shape control, precision positioning, and force control in various NASA, military and civilian applications [1, 2]. In the past decades, a great deal of effort has been devoted to developing smart materials and structures with those desired features [3-8]. A broad range of actuation approaches have been developed, including electro-magnetic, electrostatic, piezoelectric, electrostrictive, magnetostrictive, shape memory alloy, and thermal pneumatic [9]. Among these kinds of actuators, the advantages of the solid state piezoelectric actuators are large electromechanical energy conversion efficiency, broad operation frequency range, small heat generation and no electromagnetic noise. However, the disadvantage of this kind of actuator is that it has small stroke. In the 1990s, the relaxor-based single-crystal piezoelectric materials, such as Pb(MgxNb1-x)O3-PbTiO3 (PMN-PT) and Pb(ZcxNb1-x)O3-PbTiO3 (PZN-PT) with high strain and piezoelectric constant, were discovered [5, 10]. In the meantime, Newnham et al. [11] invented the concept of flextensional actuator/transducer to achieve the amplification of the displacement response. Recently, the piezoelectric PMN-PT single-crystal multilayer stack actuators and the multilayer stack-based flextensional actuators were developed at TRS [12]. These actuators demonstrated larger stroke and higher precision even at a broad range of temperatures (
