JEC COMPOSITES MAGAZINE - Issue #109 - November/December 2016 - 47

An innovative 3D placement technology

Focus
The Institute of Aircraft Design (IFB) is part of the aerospace engineering
faculty of the University of Stuttgart. It has more than 40 years of experience
in composite materials and the design and testing of aerospace, automotive
and automationstructures.
Three professors, 53 scientists and five technicians are working on both basic research topics (aircraft pre-design, simulation tools, testing methods,
new material systems, fracture mechanics, and manufacturing technologies) and application-related projects in close cooperation with industrial
partners and SMEs.
The institute is well equipped with testing facilities (material/structural
tests), a composite manufacturing lab (autoclave, hot press, RTM facility,
and textile preforming machines), FEM simulation tools, a CAD lab, a thermal analysis laboratory and a mechanical workshop.
A major focal point is process development using stitching, embroidery and
braiding machines for basic investigations and prototype demonstrations.
Fig. 2: New generation direct ply placement

LOWFLIP process has the following advantages:
- Different UD-based prepreg materials
can be used, in contrast to the use of a
single certified material system for conventional production processes. Outof-autoclave prepregs can be used to
reduce energy consumption and cycle
times. A new snap-cure prepreg system
was developed by project partner SGL,
resulting in a curing time of 15 minutes
at 120°C.
- Wide tapes up to 300 mm (or more)
are used to increase the production

efficiency of large-scale parts. Narrow
tapes can be used without modifying
the equipment, if necessary.
- A flexible industry robot cell is used
instead of expensive gantry systems,
so that investment costs can be further
reduced.
- The direct placement of the material in
a double-curved mould allows for realizing complex 3D shapes. No further
draping steps are necessary after layup.
- Very low scrap rates are possible, down
to 5% or less depending on the layup
direction and tool geometry.

Successful demonstration
A self-heated CFRP tooling with a resistive heating circuit is used to reduce thermal mass and increase heating rates. Thus,
very low overall cycle times and energy
consumption can be achieved within a
fully automated process.

Two parts for different transport applications were selected as demonstrators:
1) Aerospace: a stringer stiffened shell
for the aft section of a commercial aircraft
(A320 size).
Size: approximately 1.2 m x 1 m, monolithic skin, double curved.
2) Transport sector: a front wall for a
truck trailer (see Figures 2 and 3) with a
composite-made aerodynamic shape to
reduce drag.
Size: 2.5 m x 2.8 m, monolithic layup,
complex double-curved surface, variable
laminate thickness (2-3 mm).
Fig. 3: The LOWFLIP prototype cell during the production of a truck front wall demonstrator

No109 November - December 2016

More information:
www.lowflip.eu

/ jec composites magazine

Feature Automation

The technical development of the
LOWFLIP process was completed successfully. The prototype production cell
(8x9 m) is currently used to manufacture different demonstrator parts to fully
showcase the potential of the system and
to benchmark the process against the
state of the art.

http://www.lowflip.eu

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #109 - November/December 2016