Analysis of fiber damage mechanisms during processing of reinforced polymer melts

Abstract

This paper presents a pseudo-analytical and an indirect boundary element method (BEM) formulation for the deformation of a slow viscous flow containing fibers. Surface tractions on the fibers were integrated to compute forces. The two solutions were compared with an existing approximate solution of the fiber motion in a Newtonian fluid, developed by Burgers in 1938. The values for the overall forces on the fibers were in good agreement with the previous solution. However, the force distribution along the fiber was found to be significantly different from the constant distribution assumed by Burgers. First, an axial flow case was analyzed, where a fiber translates axially in a stationary fluid body. Second, fiber motion in shear flow was modeled. Here, a fiber at an angle of −45° with respect to the direction of the flow was studied; the angle where the fiber experiences the highest buckling forces during shear flow. In both cases, the pseudo-analytical and numerical traction loads were compared to each other and were found in good agreement. The BEM solution gave more detail of the stress fields present at the tip of the fibers.