JEC COMPOSITES MAGAZINE - Issue #111 - March 2017 - Special JEC World - 33

Simulation boosts the use of thermoplastic composites in mass production

Fig. 2: Shear angle on a thermoformed organo-sheet, as simulated with Pam-Composites

Fig. 3: Bridging defect on a thermoplastic rib, as
simulated with Pam-Composites
(Courtesy TU Delft)

compaction and avoid the uncontrolled flow
of resin so that the end product matches the
design requirements.
Pam-Composites also uses a process-oriented interface that makes the modelling and
analysis process incredibly easy. The tool
velocity, the temperature and pressure cycle,
the clamping conditions and force, the composite orientation and, as mentioned before,
the tooling design can be fully optimized
from within the software until resin pooling,
and other such defects, are minimized and
the final product is fully optimized. There are
no waste and no expensive real-world iterations - the software does the legwork.
Proper material characteristics
Material data is a key influencing parameter

for thermoplastic composite material simulations to run, and run as accurately as possible.
This requires experimental measurements
to be brought into the simulation. Two challenges remain for material characteristics.
First, composite materials are quite new and
can be made from a combination of textile
architectures, resins, and so on. The material
composition is not standardized. A standard
only seizes good practices at a precise instant.
Standards are a good way to leverage best
practices and to standardize experimental
protocols, based on the material properties
of known materials. It is therefore not surprising that standards are seldom suited to
new, innovative materials. The art of experimenting consists in knowing how to draw
from a standard, while taking the necessary
step back to evolve it. Material data, therefore, needs to be tested numerically and
experimentally using simple parts before it
is transferred to an industrial-scale model
(Figure 1).
Second, a lot of complex and time-consuming work is usually needed when moving
raw experimental data and material data into
the software. Most simulation solutions calibrate this raw data so that it works with the
software, but such data conversions bring
inaccuracies into the resulting simulations.
However, Pam-Composites, which also includes the above-mentioned die spotting
capability, does not involve any calibration.
This simplifies the entry of the material characteristics. The raw material data can be directly imported, which results in time savings
and improved accuracy in the resulting simulations. This also reduces the risk of human
error, further improving the end result.

Multi-process simulations
Thermoplastic resins are often used for RTM
(Resin Transfer Moulding) processes, where
a dry textile is positioned into a mould before
the resin is injected. RTM processes have
several advantages, including the possible
integration of functions. However, due to
the viscosity of the thermoplastic resins used,
material suppliers are working on adapting
these resins to make them compatible with
the RTM process (Figure 2).
Lowering the viscosity of thermoplastics to a
value below one Pa enables the use of thermoset production methods such as Resin
Transfer Moulding (RTM) or VacuumAssisted Resin Infusion (VARI) for large
parts such as wind turbine blades or sailing
ships, for instance. In order to achieve these
low viscosities, low-viscosity mixtures of
monomers, oligomers or prepolymers and
catalysts or initiators can be prepared and
infused into a mould, where the polymerization reactions take place after the thermoplastic liquid resin has completely wet out the
reinforcement.
Pam-Composites contains an RTM module
to help engineers predict how the resin will
flow in the preform and whether any dry
zones are created during the injection process. The incorporation of this module not
only helps keep pace with industry demand,
it also brings in cost savings as such tests can
now be carried out in the simulation space, as
opposed to the real world (Figure 3).
Conclusion
The full industrial potential of thermoplastic resins is slowly being realized. Until now,
development methods have relied on expensive real-world experiments or haphazard
simulations where the full wealth of knowledge about thermoplastic composite materials and thermoforming techniques was
not intuitively brought together to produce
a defect-free design. Pam-Composites solves
these issues. It gives engineers the opportunity to optimize and produce the perfect
product through simulations, which, in turn,
opens up a huge range of application opportunities to these environmentally important
materials in the real world.

No111 March 2017

More information:
www.esi-group.com/composites

/ jec composites magazine

http://www.esi-group.com/composites

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #111 - March 2017 - Special JEC World