JEC COMPOSITES MAGAZINE - Issue #114 - July 2017 - 27

Fast development and intelligent process control for RTM

the upper and lower parts of the blade.
- 4 resin arrival sensors (disposable): Four
disposable flow sensors were strategically positioned along the outer layer of the
preform to monitor the resin flow front
progress.
- (All permanent and disposable flow sensors also measure temperature.)
- 2 pressure sensors: Positioning the pressure sensors on the top mould close to the
inlet and vents indicate the pressure gradient between the inlet and outlet gates.
- 3 thermocouples (permanent): One thermocouple was placed at the top mould
to control the oven's temperature and 2
thermocouples were placed on top of the
product.
The sensor lay-out in the mould is shown in
Figure 4 together with the resin arrival time
stamps. The injection took place inside an
oven at elevated temperature, so the information from the sensors was the only feedback
available. Following the readings from the
sensors, the injection was very smooth while

the order of resin arrival signals was inline
with the injection strategy. First, the resin
at the venting points was recorded after 40
minutes while the flushing took 15 minutes
more. In contrast to the lab case, the curing
temperature was lowered to 100°C to avoid
any deformation of the composite tooling
and there was no post-curing. The recorded
temperature showed a peak exothermic reaction of 115°C at the root section, as can be
seen in Figure 5. It should be highlighted that
the temperature was measured on the mould
side of the product while simulations showed
a higher peak exotherm at the core side of
the root laminate. The mould was left to cure
for 12 hours without any other adjustments.
However, based on the feedback from the
cure sensors and the real-time calculations,
predicting online the Tg of the material had
already reached the targeted level of 130°C
after 6 hours, so the cure cycle could have
been 50% faster than the initially designed
one. The final part (Figure 6) was demoulded
in net shape and checked successfully against
the specifications.

Conclusions
Real-time process monitoring can provide
the foundation for process automation in
a variety of composite processes. The advantages and robustness of the resin arrival,
cure and pressure sensors and systems were
validated in practice, and the results helped
to improve the production performance at
first hand. The sensors can provide composite manufacturers with intelligent tools and
systems that can improve productivity and
quality control.
Acknowledgments
This work was partially supported
by the European Commission FP7
Programme under Grant NMP2SL-2013-608667 (Ecomise project:
Enabling Next Generation Composite
Manufacturing by In-Situ Structural
Evaluation and Process Adjustment).
More information:
www.ecomise.eu

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N°114 July 2017

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27
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Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #114 - July 2017
