Amelia M. Elliott

A procedure for creating actuated joints via embedding shape memory alloys in PolyJet 3D printing

Additive manufacturing’s layer-by-layer fabrication approach allows the user to access the entire volume of the part throughout the build process. This allows for the embedding of functional components and actuators to enable the fabrication of complex systems in a single process. A process for the embedding of shape memory alloy actuating wire within direct PolyJet 3D printed parts is presented in this article. A series of “Design for Embedding” considerations are presented for achieving successful and repeatable embedding results. These considerations include guide channel design, design of shape converters for irregularly shaped elements, and design of wire fixation points. The embedding process is demonstrated with two case studies: a simple compliant joint specimen with a straight shape memory alloy wire and an antagonistic joint design with spring-shaped shape memory alloys. The process is characterized through an exploration of the potential for surface defects in the final specimens, as well as basic quantitative and qualitative evidence regarding performance of the final embedded actuators.

Experimental study of the maximum resolution and packing density achievable in sintered and non-sintered binder-jet 3D printed steel microchannels

Developing high-resolution 3D printed metallic microchannels is a challenge especially when there is an essential need for high packing density of the primary metal. While high packing density could be achieved by heating the structure to the sintering temperature, some heat sensitive applications require other strategies to improve the packing density of primary metal. In this study the goal is to develop microchannels with high green (bound) or pack densities on the scale of 100–300 microns which have a robust mechanical structure. Binder-jet 3D printing is an additive manufacturing process in which droplets of binder are deposited via inkjet into a bed of powder. By repeatedly spreading thin layers of powder and depositing binder into the appropriate 2D profiles, complex 3D objects can be created one layer at time. Microchannels with features on the order of 500 microns were fabricated via binder jetting of steel powder and then sintered and/or infiltrated with a secondary material. The droplet volume of the inkjet-deposited binder was varied along with the print orientation. The resolution of the process, the subsequent features sizes of the microchannels, and the overall microchannel quality were studied as a function of droplet volume, orientation, and infiltration level.Copyright