Design Requirements for Amorphous Piezoelectric Polymers

An overview of the piezoelectric activity in amorphous piezoelectric polymers is presented. The criteria required to render a polymer piezoelectric are discussed. Although piezoelectricity is a coupling between mechanical and electrical properties, most research has concentrated on the electrical properties of potentially piezoelectric polymers. In this work, we present comparative mechanical data as a function of temperature and offer a summary of polarization and electromechanical properties for each of the polymers considered

Electrical Properties And Power Considerations Of A Piezoelectric Actuator

This paper assesses the electrical characteristics of piezoelectric wafers for use in aeronautical applications such as active noise control in aircraft. Determination of capacitive behavior and power consumption is necessary to optimize the system configuration and to design efficient driving electronics. Empirical relations are developed from experimental data to predict the capacitance and loss tangent of a PZT5A ceramic as nonlinear functions of both applied peak voltage and driving frequency. Power consumed by the PZT is the rate of energy required to excite the piezoelectric system along with power dissipated due to dielectric loss and mechanical and structural damping. Overall power consumption is thus quantified as a function of peak applied voltage and driving frequency. It was demonstrated that by incorporating the variation of capacitance and power loss with voltage and frequency, satisfactory estimates of power requirements can be obtained. These relations allow general gui..

Low-field and high-field characterization of THUNDER actuators

Abstract. THUNDER (THin UNimorph DrivER) actuators are pre-stressed piezoelectric devices developed at NASA Langley Research Center (LaRC) that exhibit enhanced strain capabilities. As a result, they are of interest in a variety of aerospace applications. Characterization of their performance as a function of electric field, temperature and frequency is needed in order to optimize their operation. Towards that end, a number of THUNDER devices were obtained from FACE International Co. with a stainless steel substrate varying in thickness from 1 mil to 20 mils. The various devices were evaluated to determine low-field and high-field displacement as well as the polarization hysteresis loops. The thermal stability of these drivers was evaluated by two different methods. First, the samples were thermally cycled under electric field by systematically increasing the maximum temperature from 25°C to 200°C while the displacement was being measured. Second, the samples were isothermally aged at 0°C, 50°C, 100°C, and 150°C in air, and the isothermal decay of the displacement was measured at room temperature as a function of time. Key words. piezoelectric, pre-stressed ceramic, hysteresis, temperature effect, isothermal aging Subject classification. Materials 1. Introduction. This work describes the results of a characterization study of THin UNimorph-like DrivER (THUNDER) actuators to determine the effects of metal thickness on free displacement at both sub-switching an

3D Printing of Shape Changing Polymer Structures: Design and Characterization of Materials

Additive manufacturing (AM) gives engineers unprecedented design and material freedom, providing the ability to 3D print polymer structures that can change shape. Many of these Shape Memory Polymer (SMP) structures require multi-material composites, and different programmed shapes can be achieved by designing and engineering these composites to fold and unfold at different rates. To enable SMP applications involving shape-changing geometries, it is important to have an understanding of the relationships between intermediate shapes and the initial and final designed shapes. To accomplish this, we investigated readily available 3D printable polymer materials and their thermo-mechanical characteristics to create multi-member structures. This paper demonstrates a way to generate different temporary geometric profiles on a single 3D printed shape with the same material. This paper also includes insights from thermo-mechanical analysis of the materials to help create multi-member shape-changing geometries using 3D printing.Mechanical Engineerin