JEC COMPOSITES MAGAZINE - Issue #97 - Special JEC Americas - May/June 2015 - 67

rosette, the intended fibre direction. The fibre placement process
is simulated and tape courses are
programmed, so the exact placement
and orientation of all the tows is
known. In addition, process-related
features such as gaps, overlaps and
short fibres are dealt with.
Fig. 2: CORAC "Z-section" fuselage frame. From left to right: AFP process simulation, CAD model of formed
frame on the AFP mould, the final product

More recently, software for the finite
element (FE) forming simulation of
composites has become available,
such as for instance PAM-FORM
from ESI Group. This software takes
into account the physics of the forming process and material-specific
behaviour to simulate the highly nonlinear forming process.
This software allows engineers to
predict formability, fibre paths, the
effect of the laminate lay-up and
manufacturing-induced defects such
as wrinkling.

Fig. 3: CORAC "Z-section" fuselage frame. Close-up before (left) and after (right) forming

with carbon fibre tows, all using a
single process.
Thermoforming is a well-established
process for high-volume production,
but it has only recently been applied
to complex composite parts. A 2D
laminate is heated to above the melting point of the matrix before being
formed. Both large and small parts
can be produced in this fashion.
Combining the forming process with
AFP not only allows for high-volume
production, but it also expands the
design possibilities for AFP. In this
way, parts with small inner radii can
be produced.

CORAC "Z-section" frame
A good example is the "Z-section"
produced for the CORAC programme. An innovative solution
for the automated manufacturing
of a complex "Z-section" fuselage
frame was proposed, using both fibre

placement and forming processes.
The frame was made by first laying
UD slit tapes on an AFP adapted
mould with one large inner radius,
see Fig. 2. Then the final Z shape
with small inner radii was formed on
a second mould, see Fig. 3.
The fibres had to be placed such
that after forming, the correct fibre
orientation was obtained. The final
fibre orientation depends on both
manufacturing processes; especially
their manufacturability constraints
which make it extremely complex to
determine the optimum initial position of each fibre.

Software
CATFiber is a complete composite
design and offline programming
solution for AFP. It plays a critical
part in the design for manufacturing
for AFP. The plies are sectorized to
avoid fibre wrinkles and excessive angular deviation from the engineering

To prevent defects and increase the
production rate, the process conditions can be optimized. Now, with
AFP, the laminate too can be adapted, increasing the possibilities for
optimization.

Software interface
Several iterations to the design usually have to be made before being
able to produce a formed part with
optimized strength and stiffness
properties. Besides the ply outline,
the fibre orientations, the lay-up and
the formability of the laminate might
have to be optimized as well. Here
too, the part design, the tooling,
the AFP process parameters and the
forming process parameters could be
adjusted.
The complexity of the combined
production processes necessitates
a continuous, efficient numerical
chain. Therefore, a bidirectional
interface tool is required for the
exchange of data. Particular attention
is paid to removing redundant and

No97 May - June 2015 / jec

composites magazine 67

JEC COMPOSITES MAGAZINE - Issue #97 - Special JEC Americas - May/June 2015

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #97 - Special JEC Americas - May/June 2015