Design and 3D printing of reconfigurable structures

Abstract

Bi-stable structure is the fundamental form of reconfigurable structure. The basic application of bi-stable structure is light switch which can be triggered on or off position. The degree of freedom is zero at all time. The state change is due to buckling of one of the members as force advances. Therefore the anticipated member cannot be too stiff to deter the functionality nor too weak as it might adapt permanent deformation. The stability of bi-stable structure is verified by Grubler’s criterion. The geometry of linkage members and joints are calculated to define clearance along the flexing path. Upon achieving successful pin joint bi-stable concept, consideration of adapting into fully compliant design is analysed. The golden rule of compliant joint is to have least material at the designated region to allow flexure without much resistance. Two fabrication methods, moulding and 3 dimensional printing (3DP), are deployed to compare the production duration and complexity. Eventually, 3D printing is used for the final product fabrication and different methods to feed into 3D printer are also explored. The problems encountered during 3D printing are presented for precaution to be taken in future design project. The limitations of the project are later on described and recommendations for future work are elaborated with example.