THE SMART JOINT: MODEL AND OPTIMIZATION OF A SHAPE MEMORY ALLOY/SHAPE MEMORY POLYMER COMPOSITE ACTUATOR

摘要

The Smart Joint, developed at Cornell University, is a composite device which functions as both a structural element and shape changing mechanism. Through resistive heating, the device will provide a tip deflection on the order of 5-20% of its undeflected length, with a high specific work capability. The joint possesses sufficient stiffness to function as a load-carrying element on a structure, inspired by the need to consume minimal energy through passive rigidity. An overview of Smart Joint operation is provided, followed by an improved model encompassing embedded actuators, applicable to many strain actuation systems. Previous work has developed a model that describes the shape change capability of the joint as a function of composition and layering structure, and the revised model is an extension of that work, agreeing well with finite element analysis. Benchmarking is conducted through a heuristic optimization study, providing a framework for selecting joint structure to match desired application by joint composition family. Implementation on a bat-like morphing wing is proposed that uses the Smart Joints as self-actuated hinge structures along the skeleton, capable of providing increased wing camber and tip deflections while in flight.