Development of the layered structure in a double-gated glass fiber-reinforced polypropylene injection molding: Experimental and simulated results

Abstract

The present study aims to experimentally validate numerical simulation of fiber orientation distribution performed by molding simulation software Moldex3D in a double-gated injection-molded glass fiber-filled (40 wt%) polypropylene box, by making a detailed comparison of predicted and experimentally measured fiber orientation distribution data. The modeling approach evaluated in this work consists in the implementation of the Folgar–Tucker rotary diffusion model with the invariant-based optimal fitting closure approximation for the fourth-order orientation tensor. The specimen used has a weld line in the center and sharp corners. This investigation characterizes in detail the development of the through-thickness layered structure at distinctive locations of the specimen. The sensitivity of fiber orientation distribution and the layered structure to changes upon injection time and melt temperature is also evaluated. The boxes display the typical layered laminate structure, with fibers aligned in the main flow direction near the walls (shell layer) and less oriented in the middle plane (core layer). The boxes injected at the lowest melt temperature display an additional skin layer. Unfortunately, simulation fails in predicting the five layers structure developed under these latter conditions. The grade of fiber orientation is deemed to be independent of process parameters but not the layered structure.

Weld line strength factors in a reinforced injection molded part: Relationship with predicted fiber orientation

“…From simulation results, an orientation factor (R or ) was computed as the ratio between the minimum and maximum magnitudes of the fiber orientation vector respective to the crack grow direction. As an evidence of the trustworthy of simulation results presented here, it should be noted that the predictive capacity of Moldex3D to determinate the fiber orientation state in specimens with weld lines has been validated elsewhere, 12 with a specimen injected using similar conditions.…”

“…Mechanical properties of reinforced polymer pieces containing weld lines do not depend only on the fiber content but also on the fiber orientation. 5–8,12 In this way, simulation constitutes a pertinent and relevant analysis, which in turn does not imply the laborious obtaining of micrographic samples and the complete or partial destruction of the parts to characterize the fiber orientation state. Thus, the general idea of this work is the estimation of a R wl from a fracture experiment that in turn could be related with an R or obtained from simulation.…”

“…The levels of the variables were defined in relation to previous experience in the injection of this material. 12…”

A research method to improve the quality of box-type thin-walled parts by combining parameter optimization and i nverse-deformation design

“…Due to lightweight, Plastic injection molding (PIM) as a polymer material processing method is a widely used in automotive parts [1]. It has the advantages of fast production speed, high economic efficiency and high precision, and the ability to produce complex items by injection molding, which plays an important role in the plastics industry [2]. A complete molding cycle of PIM generally has four steps: filling, holding, cooling, demoulding [3].…”