Comparison of Real and Simulated Fiber Orientations in Injection Molded Short Glass Fiber Reinforced Polyamide by X-ray Microtomography.

Rafał Żurawik,Jan-Christoph Zarges,Hans-Peter Heim,Julia Volke

doi:10.3390/polym14010029

Abstract

During injection molding of short glass fiber reinforced composites, a complex structure is formed due to the fiber movement. The resulting fiber orientation can be predicted using various simulation models. However, the models are known to have inadequacies andthe influence of process and model parameters is not clearly and comprehensively described. In this study, the aforementioned model and process parameters are investigated to determine the dependencies of the individual influences on the real and simulated fiber orientation. For this purpose, specimens are injection molded at different process parameters. Representative regions of the specimens are measured using X-ray microtomography and dynamic image analysis to determine the geometric properties of the fibers as well as their orientations. Furthermore, simulations are performed with the simulation software Moldflow® using different mesh types and densities as well as varying parameters of the MRD model to represent the real fiber orientations. The results show that different orientation areas arise in the samples, which cannot be represented with a simulation varying only one parameter. Several simulations must be carried out in order to represent flow regions occurring in the specimen as realistically as possible.

Highlights

Due to their lightweight potential combined with good mechanical properties, injectionmolded short glass fiber reinforced thermoplastics (SGFRP) are being used in ever-increasing application areas
This study focuses on the Moldflow® Rotational Diffusion (MRD) model, which is the latest advancement of fiber orientation models, implemented in the commercial injection molding software Autodesk Moldflow®
The presented images result from the specimens produced by different nozzle temperatures and flow rates, which were assumed to be significant for the formation of the fiber orientation

Summary

Introduction

Due to their lightweight potential combined with good mechanical properties, injectionmolded short glass fiber reinforced thermoplastics (SGFRP) are being used in ever-increasing application areas. The largest market is the automotive industry, where SGFRP are becoming increasingly popular to achieve the required weight and emissions reduction [1,2]. They are mainly used in covers, connector systems, bodywork, and structural components [3]. The use of glass-fiber-reinforced polyamide, e.g., for oil pans, bearings, and underhood applications, enables weight reductions of up to 50% compared to metal series components [3]. By reinforcing the polyamide with glass fibers, an increase in stiffness and strength is achieved with a simultaneous reduction in creep tendency, while at the same time, the density of the fiber-reinforced polyamide is only about 20% higher than that of the pure thermoplastic

Methods

Results

Conclusion