ABSTRACT
Abstract. Recent advances in adaptive aerospace materials have expanded their roles beyond basic vibration reduction to the area of flight control. Because full flight control requires much higher deflection levels under more extreme operating conditions, many adaptive materials cannot currently be used in this capacity. A brief survey of current flight-proven adaptive flight control devices shows that the adaptive materials carry substantial loads and are in need of hardening. A technique for flight hardening is presented which takes advantage of a mismatch in coefficient of thermal expansion between the substrate and actuator material. This mismatch places the substrate in tension and the active material in compression. The resulting precompression allows the adaptive materials to withstand much higher tensile stress fields. To demonstrate this principle, a series of PZT-5H actuators were laminated to a variety o f substrate materials in elevated temperature cures and tensile tested. M odeling was conducted via laminated plate theory with good correlation between theory and experiment. Test results show that aluminum provided the highest degree o f precompression which yielded an increase in tensile yield strength o f 89%, a jump in depoling stress of 185% with a decrease in gross actuation strain under 20%.
