Fiber Orientation Distribution Predictions for an Injection Molded Venturi-Shaped Part Validated Against Experimental Micro-Computed Tomography Characterization

FRONTINI, M.P.; MAJOR ZOLTAN; QUINTANA, M.C.; PLANK BERNHARD; ARRIAGA AITOR

Frontiers in Materials

Frontiers Media S.A.info@frontiersin.org

Año: 2020 vol. 7

This work evaluates and compares the accuracy of different fiber orientation predictionmodels for a short fiber reinforced injection molded Venturi-shaped part which displaysvariable thickness. The experimental characterization of the specimen fiber orientationdistribution (FOD) was carried out by the micro computed tomography technique(micro-CT). The computational study of fiber orientation predictions was performedusing Moldex3D. All the possible combinations of the Folgar-Tucker (FT) and improvedAnisotropic Rotary Diffusion (iARD) rotary diffusion models and the Hybrid (Hyb),Orthotropic (ORE), and Invariant Based Optimal Fitting (IBOF) closure approximationswere considered. The relevance of the Retardant Principal Rate (RPR) model onpredictions results was also evaluated. The values of the fiber-fiber (Ci), matrix-fiber (Cm)interaction coefficients and the alpha-RPR parameter were varied in a significant range inorder to find the set of parameters that better fits the experimental fiber orientation data.The parameters? sensitivity effect over the second order orientation tensor componentswas quantified via the Analysis of Variance (ANOVA) statistical method. The experimentalmicro-CT results show an increase in the fiber orientation degree at the specimenconstriction region due to the narrowed cavity and the Venturi effect. The comparisonof the experimental and predicted orientation profiles demonstrates that the predictionsof the iARD model, in combination with the IBOF closure approximation, are the mostaccurate for the case studied. However, simulations fail to estimate the change inorientation caused by variable thickness and section. ANOVA results prove that theorientation tensor component in the flow direction (a11) is more sensitive to changesin alpha-RPR and Ci coefficient, while the perpendicular components (a22, a33) are also