JEC COMPOSITES MAGAZINE - Issue #105 - June 2016 - 35

used to generate physical parts for visualization purposes. Finished parts were
only required to keep their mechanical
integrity for handling and demonstration purposes. The focus was not
on designing materials tailor-made
for a specific purpose nor fine-tuning
process parameters, and deposition
strategies to reach the best dimensional
accuracy and part performance. This
lack of process control extends to the
qualification process. The production
quality of a part will rely on the operator's skills and experience to constantly
adjust process parameters. If cost- and
time-consuming trial-and-error attempts could be avoided by providing
reliable sensitivity quantification on
process parameters to secure consistent
printing conditions, AM would become a robust manufacturing method.

Simulation tools
e-Xstream engineering is developing
simulation tools within the Digimat
software suite for SLS and FDM process modelling (figure 1). These tools
enable engineers to design 3D printed
parts that meet all the dimensional and
structural requirements while accounting for the chosen printing technology
specificities. The proposed approach
to additive manufacturing modelling
is built along three deeply connected
aspects:
- Material engineering: design new

materials whose microstructure and
physical properties are consistent.
Both with the requirements of a specific AM technology and the targeted
final application.
- Process simulation: optimize printing parameters to improve dimensional accuracy, surface finish and
reduce manufacturing time while predicting residual stresses and strains.
- Evaluate and optimize the performance of 3D printed parts: simulate
the mechanical response of as-manufactured parts to improve part
shape and manufacturing orientation
including real printed dimensions,
process-induced defects and local
material properties.

Polimotor project
The presented workflow was successfully applied to the Polimotor plenum
from the Polimotor 2 project, whose
principal material sponsor is Solvay,
a global leader in advanced polymer
solutions (figure 2). The Polimotor
project aims to open the way for a
technological breakthrough in the
automotive sector by replacing up to
ten metal parts by plastic materials in
the Polimotor 2 engine. The studied
plenum is produced through selective laser sintering using a Sinterline®
Technyl® polyamide 6 (PA6) powder
grade reinforced with a 40% loading of
glass beads.

Confirming the design
A multiscale thermomechanical material-reinforced plastic was created with
Digimat, and subsequently used for
both process and structural engineering. The layer-by-layer manufacturing
of the plenum was modelled, followed
by a static calculation to establish the
ultimate pressure loading the part
could withstand while operating. A low
distortion from the targeted shape was
predicted, as well as a maximum sustained pressure of 9.1 bars, which confirmed the plenum design. In addition,
manufacturing guidance was provided
by optimizing the printing direction
such that the ultimate sustainable load
could be increased by 40% without
adjusting the geometry.

Process control
Integrated structural and material
design tools are needed to accelerate
the adoption of AM by the aerospace
and automotive design community and
to promote new innovative structural
designs needed to save energy and
weight. Experimental feedback is not
enough to build a reliable production
workflow. Process control is the key
to reach the desired dimensional and
structural requirements of 3D printed
part design. n
More information:
www.e-xstream.com

No105 June 2016 / jec

Feature Simulation

Fig. 2: (a) Polimotor 2 plenum printed with Sinterline®; (b) distortion - distance to targeted part (mm); (c) failure indicator distribution yellow color indicates critical
failure spots

composites magazine 35

http://www.e-xstream.com

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