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The use of a direct particle simulation to predict fiber motion in polymer processing

Pérez, Camilo, 1987-, dissertant

Publication Details Click to collapse Cite/Export

  • Creator by Camilo Pérez
  • Format Books
  • Publication [Madison, Wis.] : [University of Wisconsin--Madison], 2016.
  • Physical Details
    • 1 online resource (xi, 104 pages) : illustrations (some color)
  • OCLC ocn957677110

Summary

  • A particle level simulation to model the non-Brownian motion of fibers under small Reynolds flows was evaluated and used to study the dynamics of fiber suspensions in the context of short fiber reinforced polymeric materials processing. In the model, each fiber is represented as a chain of linked rigid segments. Hydrodynamic, contact and bending effects are imposed unto them. For single fibers, the dynamics under simple shear flow were compared to Jefferys solution for different hydrodynamic approximations, the effect of coupling the equations of motion of the fiber and the fluid was considered and the validity of the approximations used to estimate the fiber deformation was evaluated by comparing results obtained with the simulation with results obtained with large deformation theory. The results show that there is not a significant difference in the hydrodynamic behavior of single fibers when using different hydrodynamic approximations for cylinders, nor a fiber-fluid coupled system. The deflection of a fiber is well approximated by the model if the aspect ratio of the fiber segments is small. For fiber suspensions the orientation development for elongational and shear flows were compared with reported experimental data. The results show that the simulation produces accurate results when the concentration is either high or low. The selection of parameters used for the collision response between bodies affects the orientation results. A test to choose appropriate values for the contact force constant is proposed. The interaction coefficient of the Folgar-Tucker model for fiber orientation prediction was obtained for an industrial grade material. Results of the interaction coefficient were computed for different fiber contents and aspect ratios, the simulations show agreement with experimental results. Results show that the interaction coefficient depends on the fiber content, nominal fiber aspect ratio and shear rate.

Notes

  • Advisor: Tim A. Osswald.
  • Ph.D. University of Wisconsin--Madison 2016.
  • Includes bibliographical references (pages 97-104).