Fiber orientation in the frontal region of a center-gated disk: Experiments and simulation

Abstract

Fiber orientation in the frontal region of a center-gated disk was measured for the first time and compared with orientation predictions using standard Folgar-Tucker and the reduced strain closure (RSC) model in coupled flow simulations. Fiber orientation was experimentally measured along three different heights representative of shell, transition and core layers, in order to understand the evolution of orientation along the radial direction in the frontal region. Orientation predictions of the Folgar-Tucker model and its two modified versions, the delayed Folgar-Tucker model and the RSC model were assessed against the measured experimental data. Orientation predictions with all three models showed a drop in orientation near the front, which was in qualitative agreement with the experimental data. Modified versions of the Folgar-Tucker model showed a relatively larger drop in orientation in the shell layer with predictions being relatively closer to experimental values. However, no significant slowdown was observed with the modified versions in the transition and core layers. With coupling of flow and orientation, the frontal flow region was slightly larger and orientation predictions showed only slight improvement. A significant improvement in the frontal region was obtained when a lower value of the interaction coefficient was used.

Fiber suspension in 2D nonhomogeneous flow: The effects of flow/fiber coupling for Newtonian and power-law suspending fluids

“…As for the center-gated disk, Verweyst and Tucker [7] showed that the effects of coupling are modest and are only noticeable near the center of the disk. Mazahir et al [9,10] conducted coupled transient simulations to predict fiber orientation in a center-gated disk, employing slow orientation kinetics such as the reduced strain closure model [11]. They found that the coupling effect is very small when assessed against experimental data measured in the shell, transition, and core layers but an improvement is observed in the frontal flow region.…”

“…or(4). The FP equation, Eq (10),. provides the rod orientation dynamics equation represented by Ψ, from which the tensorial terms in angular brackets, arising in Eqs (3).…”

“…Hence, considering both accuracy and computational time, a fine mesh size was selected for all the computations done in this paper.Also, in all computations presented in this work, the parameters have the following values:a r ¼ 20, f f ¼ 10%, h=R ¼ ffiffiffiffiffiffiffiffiffiffi π=f f q(this condition corresponds to the case of aligned fibers and is kept constant over the different simulations even if the particles orient), η 0 ¼ 1 Pa s, K ¼ 1 Pa s m , and m ¼ 0:3. An interaction coefficient of C I ¼ 0:01 was selected for the example problem and the artificial numerical diffusion coefficient, c num , is set to 10 À5 m 2 =s for the spatial diffusion in the FP equation, Eq (10)…”

Kriging‐based orthotropic closure for flow‐induced fiber orientation and the part stiffness predictions with experimental investigation

“…Agboola et al employed several fiber orientation tensor closure approximations for isotropic rotary diffusion model and anisotropic rotary diffusion model and compared the simulations with results by the numerically exact spherical harmonic method. And Mazahir et al firstly measured the frontal region fiber orientation of center‐gated disk and compared with orientation predictions of standard Folgar–Tucker and reduced strain closure model in coupled flow simulations, they evaluated the fiber orientation in transient simulations by Folgar–Tucker and reduced strain closure model and compared the simulations with experimental data measured in the shell, transition, and core layers. Meyer et al predicted short glass fiber orientation generated during the filling of an end‐gated plaque, and also proposed a method to simulate the flow in the sprue, gate, and mold region to predict fiber orientation within the end‐gated plaque using orientation parameters fit to experimental data, they also investigated the effect of initial conditions on predicting long glass fiber orientation during the filling of a center‐gated disk.…”

Sequential kriging‐based closure approximations for flow‐induced fiber orientation and prediction of composite stiffness

“…As a result, knowing the flow induced fiber orientation is of great importance because the fiber orientation state significantly affects the composite mechanical properties. Accordingly, accurate and efficient predictions of the fiber orientation are challenging tasks and have been investigated for many years owing to their industrial applications .…”