Design of Planar Multi Degree of Freedom Morphing Mechanisms

Abstract

This paper seeks to advance the design of planar multiloop shapechanging mechanisms used in a variety of applications, such as morphing extrusion dies and airfoils. The presence of defects is a limiting factor in finding suitable singledegreeoffreedom (DOF) morphing mechanisms, particularly when the number of shapes to achieve is large and/or the changes among those shapes are significant. This paper presents methods of designing multiDOF mechanisms to expand the design space in which to find suitable defectfree solutions. The primary method uses a building block approach with Assur group of class II chains, similar to the current 1DOF synthesis procedure. It is compared to both the 1DOF procedure and an alternative multiDOF procedure that generates mechanisms with singleDOF subchains. In all cases, a genetic algorithm is employed to search the design space. Two example problems involving four prescribed shapes demonstrate that mechanisms exhibiting superior shape matching are achieved with the primary multiDOF procedure, as compared to the other two procedures.