Modeling orientation evolution of discontinuous fiber composites during processing
A method is developed to model the evolution of orientation during processing of composite materials with high aspect ratios and volume fractions. Current simulations of orientation are limited by assumptions in dilute fiber models, and fail to account for the development of anisotropic viscosity. An analogy to solid mechanics enables a new anisotropic viscosity simulation, which accounts for the coupled effects of fiber orientation and composite fluid flow. Anisotropic viscosity relationships have already been developed and the literature for these is reviewed. Viscosity relationships are evaluated using a novel viscous micromechanics approach, which provides a level of precision and detail that is difficult to obtain experimentally. A rigid body physics model for determining the initial orientation state in materials with an inhomogeneous precursor material is also developed. This rigid physics simulation is used to determine void content and variation of initial properties. Model results are compared to microscopic measurements and CT scans under experiments using controlled initial orientation states. The proposed model is also compared to current mold simulation models under the same conditions. Bounds are identified for when the assumptions in this work are applicable.
Pipes, Purdue University.
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