JEC COMPOSITES MAGAZINE - Issue #105 - June 2016 - 29

microstructure

Simulation technology for fibre concentration
prediction in lightweight FRP product designs

By
Huan-CHang (Ivor) Tseng, r&D ProjeCT Manager,
Wen-HsIn (DebbIe) Weng, PM DePuTy ProDuCT Manager,
MeI-CHun (yvonne) LIu, MarkeTIng sPeCIaLIsT,
CoreTeCH sysTeM (MoLDex3D) Co., LTD.

Fig. 1: Geometry of the model with different rib
thicknesses

analysis software programs. However,
fibre concentration prediction capability
was previously lacking in mould-filling
analysis. It was essential to incorporate
fibre concentration in mould-filling
analysis because, when compared to
fibre orientation and fibre length, fibre
concentration has a more dominating
effect on flow behaviour. The higher the
fibre concentration value, the greater
the viscosity will be. A higher viscosity
will decrease the velocity of the polymer
melt as it moves forward, which may
cause subsequent surface defects. Thus,
a significant improvement was made
recently to include fibre concentration
prediction in Moldex3D software for a
more comprehensive fibre analysis in
FRP applications.

Observation of fibre dispersion
in different rib thicknesses
Fibre concentration is a clear indicator
to observe the effect of fibre dispersion.
The following experiment was designed
to investigate the fibre dispersion
behaviour in different rib thicknesses.
As shown in Figure 1, a model with
different rib thickness designs, ranging
from 4mm to 0.5mm, was investigated.
The initial fibre concentration of the
melt was set as 30wt% short glass fibre/

Fig. 2: Fibre concentration in different rib
thicknesses

PA6. Figure 2 shows Moldex3D's fibre
concentration analysis for different
rib thicknesses. The yellow and green
colours indicate the higher and lower
fibre concentrations, respectively. A
higher fibre concentration (34wt%) and
a more uniform fibre distribution are
observed in the thickest rib, whereas the
thinnest rib has a lower fibre concentration (28wt%) and a more uneven
fibre distribution. In Figure 3, it can be
observed that the thinner rib section
exhibits a smaller average fibre concentration value, and vice versa. As a result,
it can be concluded that fibre dispersion
results will vary with different rib thickness designs: the thinner the rib, the
more difficult it is for the polymer melt
to move forward, therefore resulting in
a lower fibre concentration value and
uneven fibre distribution.

No105 June 2016 / jec

composites magazine

FEATURE SIMULATION

n recent years, the production of plastic products, especially for large-sized
parts, has been moving towards "lightin-weight and high-in-strength" design
concepts. Fibre composite materials are
being used more and more extensively
due to their superior strength/weight
ratio, durability, material properties, and
impact resistance. The success of fibre-reinforced plastics (FRP) processing highly
depends on three major parameters: fibre
orientation, fibre length/breakage, and
fibre concentration. These parameters are
important factors affecting the filling behaviour, warpage, and structural integrity
which ultimately determines the quality
of the final FRP parts.
The research developments in fibre
orientation and fibre length predictions
have been well-developed and included in commercialized mould-filling

In addition to fiber orientation and fiber length/breakage, fiber
concentration is also a key factor to consider when developing a
fiber-reinforced plastic (FRP) product. The simulation capability of
fiber concentration prediction has been made available in mold-filling
analysis software, Moldex3D for users to gain a more comprehensive
fiber microstructure analysis for their FRP product designs. The study
described in this paper demonstrates the importance of fiber concentration factor and how the simulation prediction helps users better
evaluate the product quality and strength when using fiber-reinforced
materials.

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #105 - June 2016