A study of fiber orientation in particle-loaded suspensions using a direct simulation method with collision strategy
Date
2016
Authors
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Publisher
University of Delaware
Abstract
Short-fiber reinforced composite materials are widely in use in the manufacturing industries to bridge the property gap between continuous-fiber composites and unreinforced materials. Short-fiber composites can effectively strengthen the matrix materials along the fiber length direction, and can still be processed by highly-automated and economical methods such as injection or compression molding. It’s essential to understand and predict the fiber orientation and its influence on the mechanical properties of the composite. However, the hydrodynamic interactions between the matrix and the fibers, and the inter-fiber interactions are not fully understood yet. Sometimes circular particles are added to the matrix for toughening and this may also influence the orientation of the short fibers during flow. In this thesis, we adopt a two-dimensional direct simulation method to investigate, for the first time, the effect of the presence of circular particles on the fiber orientation of short-fiber suspensions. To deal with the collision between fibers or fibers and particles, an ad-hoc method is proposed and developed. We predict the time-evolution of the elliptical fiber orientation as the volume fraction and aspect ratio increases, and compare it with that of the fiber-particle suspensions. The interaction coefficient C1 is calculated and compared with existing models. It is found that the presence of circular particles increases the rotary diffusion of a fiber suspension, and that, as the content of circular particles increases, the fiber alignment in the direction of shear is less pronounced.