A 3D Printed Morphing Nozzle to Control Fiber Orientation during Composite Additive Manufacturing. Issue 1 (25th November 2020)

• Record Type: Journal Article
• Authors: Armstrong, Connor D.; Todd, Noah; Alsharhan, Abdullah T.; Bigio, David I.; Sochol, Ryan D.
• Is Part Of: Advanced materials technologies. Volume 6:Issue 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-25
• Subjects: 3D printing -- 4D printing -- additive manufacturing -- direct ink writing; Materials science -- Periodicals; Technological innovations -- Periodicals; Materials science; Technological innovations; Periodicals; 620.1105
• DOI: 10.1002/admt.202000829
• Languages: English
• ISSNs: 2365-709X

Abstract

Abstract: Fiber‐filled composite materials offer a unique pathway to enable new functionalities for systems built via extrusion‐based additive manufacturing (or "3D printing"); however, challenges remain in controlling the fiber orientations that govern ultimate performance. In this work, a multi‐material, shape‐changing nozzle—constructed by means of PolyJet 3D printing—is presented that allows for the spatial distribution of short fibers embedded in polymer matrices to be modulated on demand throughout extrusion‐based deposition processes. Specifically, the nozzle comprises flexible bladders that can be inflated pneumatically to alter the geometry of the material extrusion channel from a straight to a converging–diverging configuration, and in turn, the directional orientation of fibers within printed filaments. Experimental results for printing carbon microfiber‐hydrogel composites reveal that increasing the nozzle actuation pressure from 0 to 100 kPa reduced the proportion of aligned fibers, and notably, prompted a transition from anisotropic to isotropic water‐induced swelling properties (i.e., the ratio of transverse to longitudinal swelling strain decreased from 1.73 ± 0.37 to 0.93 ± 0.39, respectively). In addition, dynamically varying the nozzle geometry during the extrusion of continuous composite filaments effects distinct swelling behaviors in adjacent regions, suggesting potential utility of the presented approach for emerging "4D printing" applications. Abstract : A PolyJet 3D printed morphing nozzle is presented to enable on‐demand regulation of the orientation of short fibers within printed filaments throughout extrusion‐based composite additive manufacturing processes. The ability to modulate the nozzle geometry allows for a degree of reorientation of embedded fibers capable of effecting a transition from anisotropic to isotropic water‐induced swelling properties for printed filaments.