Shape Memory Polymer Based Reconfigurable Compliant Mechanisms: An Exploration

This paper explores the concept of reconfigurable compliant mechanisms. We define these to be fully or partially compliant mechanisms whose performance can be modified after they have been fabricated. Specifically, we are interested in the nature and extent of in situ reconfigurability in compliant mechanisms. In other words, we seek to understand the range of performance that can be achieved by these mechanisms without requiring significant reassembly. The material properties such as the storage modulus of a newly studied class of materials — shape memory polymers — vary by over an order of magnitude over a temperature range of 20 – 50 C. These polymers also allow the fixing of moderate to large strains (20 – 75%) experienced at high temperatures for extended periods of time, while retaining the ability to remember their original shape when reheated to the same high temperatures. These two properties make shape memory polymers a natural candidate for the fabrication of reconfigurable compliant mechanisms. We explore various means for introducing reconfigurability in compliant mechanisms, and from these, select a subset that is suitable for in situ reconfiguration. Quasi-static nonlinear finite element simulations are used to study the change in performance due to reconfiguration of four fully compliant mechanisms made of a shape memory polymer. Preliminary results indicate that noticeable qualitative and quantitative changes in performance can be achieved by these mechanisms.