pps proceeding - Abstract Preview
pps proceeding
Symposium: S17 - Special Symposium: Additive manufacturing (3D printing)
Oral Presentation
 
 

Effect of Shear and Extensional Flows on Liquid Filler Morphology in Additive Manufacturing

Bigio David I (1)*, Sangli Aditya N (1)

(1) University of Maryland - Maryland - USA

The nozzles of current polymer based additive manufacturing machines can be modified to inject immiscible liquids whose morphology can be controlled by active and passive means. In this research, the active deformation induced by the flow rate through the nozzle as well as geometry induced effects on droplet deformation are experimentally studied in a model hyperbolic converging nozzle. Droplets injected at the center of the nozzle undergo pure elongation in the flow. The critical Capillary number – which indicates the maximum Capillary number at which the droplet is stable – is heuristically interpreted by performing experiments over a range of initial Capillary numbers. Maximum obtainable non dimensional deformation of droplets is around 0.68 regardless of further increase in initial Capillary number. When droplets are injected offset of the centerline, shear influenced deformation is observed which causes droplets to affinely deform. Due to the planar nature of the nozzle, velocity gradients are higher into the plane and shear rate is an order of magnitude higher than extensional rate along offset injection positions. Non dimensional measures of droplet morphology in the nozzle are obtained through experiments which are useful when the nozzle is scaled down and incorporated into polymer based additive manufacturing machines.