Showing papers by "Jack R. Vinson published in 2006"

Continued Efforts in the Development of Piezo-Activated Composite Sandwich Fins

Abstract: Over the past four years, the University of Delaware's Center for Composite Materials and the US Army Research Laboratory have spearheaded a team of researchers developing piezo-electrically actuated smart fins for use in the guidance and control of surface-to- surface projectiles as well as other military related applications. This project has undergone several iterations yielding a current design consisting of a piezoelectric sandwich structure potted into a steel spar and behaving as a cantilevered thin panel. The Macro Fiber Composites (MFC's) technology developed by NASA, make the current sandwich design feasible. With one MFC patch adhesively bonded to each side of a thin host panel, controlled angular deflection is achieved by electrically activating each of the patches. The most recently achieved milestone for the project involved demonstrating the feasibility of the thin panel design. The results of these feasibility demonstrations, as well as the foundational theories and principles, have been presented in various formats to include the 2005 AIAA conference. The current focus of the project has been on better characterizing the existing fins and increasing the understanding of their behavior, all with a view towards increasing the performance of these fins in a real, load-bearing environment. To help remedy this situation as well as provide a basis for improved performance, increased laboratory capabilities have been coupled with experimentation to provide insight into the following areas: parameter based sensitivity analysis, torque vs. deflection analysis, hysteresis, and potential for control. The theoretical sensitivity analysis performed examined the change in the free deflection, stiffness, and force generated due to alterations in various design variables to include the thickness and modulus of elasticity of the MFC patches, adhesive layers, and host material, as well as other parameters. This analysis indicates that a thinner host material with a greater modulus of elasticity should yield a sandwich structure capable of achieving greater deflection without sacrificing either the stiffness or the force generating capabilities. To serve as a basis for comparison, applied torque vs. achievable deflection curves have been produced for many of proposed structure designs. These torque deflection curves play a major part in both the decision making process as to what designs to manufacture, as well as comparing the performance of the manufactured fins.