Macrofiber piezoelectric composite for lunar exploration actuator

Abstract

Understanding the nature and location of water and other resources on Earth's Moon is an essential component to the National Aeronautics and Space Administration's (NASA) space exploration efforts. To aid in these exploration efforts, an investigation into lightweight and reliable materials for a lunar valve actuator design has lead to characterizing the lifetime performance of the piezoelectric fiber composite, macro fiber composite (MFC). MFC's are thin rectangular patches made of polyimide film, epoxy and a single layer of rectangular lead zirconium titanate fibers and are commercially available. As a basis for this consideration, the useful life of the MFC is being characterized to determine the effect of temperature on the performance of the material as it is fatigued by cyclical piezoelectric excitation or actuation. The test specimen consist of the MFC laminated to a cantilevered stainless steel beam using epoxy and is actuated at the first resonant frequency of the beam laminate by the cyclic application of 1000 volts. Strain and beam tip displacement measurements are used as a basis for determining the performance of the MFC as it is cyclically actuated under various operating temperatures. The temperature of the beam laminate is held constant during cyclic actuation and cycled to failure or 250 million cycles, to determine the useful life of the MFC over a temperature range from -15°C to 145°C. The results of the experimentation efforts show a strong temperature dependence on operational life for the MFC. No significant degradation in operational performance was identified thru monitoring of the MFC, as the MFC was cyclically actuated up to the point of failure, regardless of temperature or actuation cycle. The results of the experimental testing can be used to better inform designs, such as actuators, using MFC in environments where operational temperatures differ from standard laboratory temperatures, as well as, to better design temperature controlled environments where MFC's are used as actuators.