Dynamic Tuning of Structures for Aeroelastic Performance using Multiphase Material

Abstract

This thesis reports the dynamic performance of aerospace structures with embeddedmultiphase materials with tunable stiffness and damping parameters. Aerospace structures face the harmful effects of environmental and operational damage due to (i) mechanical stresses generated by vibrations; and (ii) thermal stress buildup from aerodynamic heating. This has negative effects on performance. This study proposes a novel method for mitigating both while maintaining desirable flight characteristics at less stress-inducing conditions. The proposed process would redirect thermal energy generated from aerodynamic heating to create internal pressure by leveraging the expansion that occurs by phase change in specific materials. A proof of concept is demonstrated that the dynamics of an aerospace structure can be programmed to adapt to counter vibratory loads by manipulating the thermal pressure of the multiphase material. To this end, the multiphase material reduces the intensity of the kinetic and thermal energy simultaneously. Experimental tests are presented to characterize the multiphase materials, demonstrate stiffness and damping tuning with heat, and provide a comparison between using single-phase and two-phase materials in this concept. Thermal and modal simulations are then used to provide validation and a better understanding of why this concept works. Results show that the increase in internal thermal pressure with a change of 30K was found to increase the damping of the structure by 50% while counteracting the natural drop in stiffness that occurs with temperature increase. This demonstrates that a viable concept has been successfully developed with the potential to pave the way for novel use of multiphase materials in aerospace structures and adaptive vibration control.