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Title: Fiber motion in highly confined flows of carbon fiber and non-Newtonian polymer [Advanced modeling of non-Newtonian polymer and carbon fibers]

Abstract

Inks compounded of short carbon fibers suspended in polymer resin can be extruded to produce composite materials during additive manufacturing or 3D printing processes. The flow process induces anisotropic orientation of the fibers which is set into the matrix and significantly affects the mechanical and physical properties of the final product. Therefore, the flow of fiber suspensions needs to be understood in order to predict the orientation distribution of the fibers during such manufacturing processes. There is still a lack of knowledge for extrusion of the complex mixture of a non-Newtonian polymer containing a high-volume fraction of fibers with high fiber aspect ratio, where both inter-particle, fluid-particle and fiber-wall interactions are computationally evaluated. This paper presents predictive numerical simulations and experimental results of such confined flow in a concentrated regime. The code is based on Lagrange multiplier technique and resolves each particle and interaction between the fibers and surrounding fluid and nozzle walls. We investigate numerically how the fiber length impacts the fiber alignment during extrusion. We found that a fiber length above 67% of the nozzle's diameter induces dramatic change in the fiber flow, causing fibers to concentrate at the nozzle boundaries with very low concentration of fibers inmore » the center of the nozzle. It was found that the best fiber alignment is reached for fiber lengths equal to 40–50% of the nozzle diameters. Numerical findings are supported by experimental results. In conclusion, this work improves understanding of fiber orientation during 3D printing and is an important milestone for the prediction of the complex mechanical properties of additively manufactured fiber composites.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1497279
Report Number(s):
LLNL-JRNL-739021
Journal ID: ISSN 0377-0257; 892093
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Non-Newtonian Fluid Mechanics
Additional Journal Information:
Journal Volume: 265; Journal Issue: C; Journal ID: ISSN 0377-0257
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; Carbon fiber; Non-Newtonian fluid; Additive manufacturing; Lagrange multipliers; Numerical modeling; Direct ink writing

Citation Formats

Kanarska, Y., Duoss, E. B., Lewicki, J. P., Rodriguez, J. N., and Wu, A. Fiber motion in highly confined flows of carbon fiber and non-Newtonian polymer [Advanced modeling of non-Newtonian polymer and carbon fibers]. United States: N. p., 2019. Web. doi:10.1016/j.jnnfm.2019.01.003.
Kanarska, Y., Duoss, E. B., Lewicki, J. P., Rodriguez, J. N., & Wu, A. Fiber motion in highly confined flows of carbon fiber and non-Newtonian polymer [Advanced modeling of non-Newtonian polymer and carbon fibers]. United States. doi:10.1016/j.jnnfm.2019.01.003.
Kanarska, Y., Duoss, E. B., Lewicki, J. P., Rodriguez, J. N., and Wu, A. Fri . "Fiber motion in highly confined flows of carbon fiber and non-Newtonian polymer [Advanced modeling of non-Newtonian polymer and carbon fibers]". United States. doi:10.1016/j.jnnfm.2019.01.003.
@article{osti_1497279,
title = {Fiber motion in highly confined flows of carbon fiber and non-Newtonian polymer [Advanced modeling of non-Newtonian polymer and carbon fibers]},
author = {Kanarska, Y. and Duoss, E. B. and Lewicki, J. P. and Rodriguez, J. N. and Wu, A.},
abstractNote = {Inks compounded of short carbon fibers suspended in polymer resin can be extruded to produce composite materials during additive manufacturing or 3D printing processes. The flow process induces anisotropic orientation of the fibers which is set into the matrix and significantly affects the mechanical and physical properties of the final product. Therefore, the flow of fiber suspensions needs to be understood in order to predict the orientation distribution of the fibers during such manufacturing processes. There is still a lack of knowledge for extrusion of the complex mixture of a non-Newtonian polymer containing a high-volume fraction of fibers with high fiber aspect ratio, where both inter-particle, fluid-particle and fiber-wall interactions are computationally evaluated. This paper presents predictive numerical simulations and experimental results of such confined flow in a concentrated regime. The code is based on Lagrange multiplier technique and resolves each particle and interaction between the fibers and surrounding fluid and nozzle walls. We investigate numerically how the fiber length impacts the fiber alignment during extrusion. We found that a fiber length above 67% of the nozzle's diameter induces dramatic change in the fiber flow, causing fibers to concentrate at the nozzle boundaries with very low concentration of fibers in the center of the nozzle. It was found that the best fiber alignment is reached for fiber lengths equal to 40–50% of the nozzle diameters. Numerical findings are supported by experimental results. In conclusion, this work improves understanding of fiber orientation during 3D printing and is an important milestone for the prediction of the complex mechanical properties of additively manufactured fiber composites.},
doi = {10.1016/j.jnnfm.2019.01.003},
journal = {Journal of Non-Newtonian Fluid Mechanics},
issn = {0377-0257},
number = C,
volume = 265,
place = {United States},
year = {2019},
month = {1}
}

Journal Article:
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