Y. Swolfs, M. Mehdikhani, S.V. Lomov (Editors)
Leuven, 15-16 September 2021
DESIGN OF A DEPLOYABLE COMPOSITE MESH TO FORM A SEGMENT OF A
CIRCULAR CYLINDRICAL SURFACE
Gokul Ganesh Murali1, Paul Robinson1, Alexander Bismarck2, and Christoph Burgstaller3
1 The Composites Centre, Department of Aeronautics, Imperial College London,
South Kensington Campus, London SW7 2AZ, United Kingdom.
Email: firstname.lastname@example.org, email@example.com
2 Polymer and Composite Engineering (PaCE) group, Department of Material Chemistry,
University of Vienna, Waehringer Strasse 42, A-1090 Wien, Austria.
3 Transfercenter für Kunststofftechnik (TCKT),
Franz-Fritsch-Straße 11, A-4600 Wels, Austria.
Keywords: Shape memory composites, Residual stress, Interleaved composites, Finite
Session topics: Structural applications
In this work, we have used finite element (FE) modelling to develop an interleaved composite
mesh structure capable of deploying along a curved path to form a segment of a circular cylindrical
surface. Such mesh structures could allow the creation of semi-permanent deployable shelters for
people and vehicles, especially during disaster relief and humanitarian assistance.
Interleaved composites have previously been shown to display controllable stiffness and shape
memory characteristics. In these works, the composites were re-shaped (or programmed) at an
elevated temperature after curing, cooled to retain the new shape and then deployed by heating the
composites to return them to their cured state [1, 2]. A mesh made of interleaved composite which can
be deployed from a compact as-cured state into an expanded planar mesh (see Figure 1a) has been
previously developed and investigated using FE analysis [3, 4]. The design of this mesh structure
exploits thermal bending of 0°/90° laminates to avoid the shape programming step.
To design a composite that can deploy into an expanded mesh forming the segment of circular
cylindrical surface (see Figure 1b), a similar approach is adopted with the utilisation of thermal
twisting (in addition to thermal bending) of 0°/θ° and 0°/-θ° (0<θ<90) laminates.
The layup sequence of the upper wall of a mesh cell is shown in Figure 1c. (A PTFE film is
used between the upper and lower walls of the cell to ensure the cell can open.) The layup shown here
consists of four repeats of the 0°/θ° sublaminates (and 0°/-θ° sublaminates) which are separated by a
polystyrene (PS) interleaf or a 0° ply. In the as-cured state, the composite will not be perfectly flat
since the layup is not symmetric. However, as the number of repeats of the sublaminate is increased,
the composite tends to become flatter.
Heating the cured laminate to the glass transition temperature of the PS (Tg-PS) results in
softening of the interleaves, thus allowing the sublaminates to be free to undergo thermal distortion
(bending and twisting) caused by the difference between curing temperature and Tg-PS. Subsequent
cooling ‘locks in’ this distorted shape. Finite element analyses have been performed with ABAQUS
using the properties of Hexcel Fibredux 914C-TS-5-34% (cured thickness of 0.125 mm) for the CFRP
plies and the geometry shown in Figure 1c. The predicted shape of the mesh wall on heating is shown
in Figure 1d.
By modifying θ, different combinations of opening and twisting of a mesh cell are produced.
The average expansion ratio percentage (considered as 100*δ/span, where the opening displacement,
δ, and span are defined in Figure 1d) and the deployment angle (φ) are plotted in Figure 2 for a range
of θ values. It can be seen that the expansion ratio has a maximum value at θ = 90° and decreases with
a decrease in θ. For the θ values considered, the deployment angle reaches a maximum at θ = 45° and
Gokul Ganesh Murali, Paul Robinson, Alexander Bismarck and Christoph Burgstaller
decreases as θ approaches 0° or 90°. An experimental investigation is underway to validate the
predicted behaviour of the deployable mesh.
Figure 1 Interleaved composite meshes capable of deploying along (a) a plane and a (b) curved
path to form a segment of a circular cylindrical surface, (c) the layup of one half of the upper
wall of the mesh cell and (d) predicted deformation of mesh wall
0 15 30 45 60 75 90
Expansion ratio (% of span)
Deployment angle (φ°)
Figure 2 Expansion ratio and deployment angle for different
composite layups with different ‘θ’ parameter
 H. A. Maples, S. Wakefield, P. Robinson, and A. Bismarck, “High performance carbon
fibre reinforced epoxy composites with controllable stiffness,” Compos. Sci. Technol.,
vol. 105, pp. 134–143, 2014, doi: 10.1016/j.compscitech.2014.09.008.
 P. Robinson, A. Bismarck, B. Zhang, and H. A. Maples, “Deployable, shape memory
carbon fibre composites without shape memory constituents,” Compos. Sci. Technol.,
vol. 145, pp. 96–104, 2017, doi: 10.1016/j.compscitech.2017.02.024.
 B. Zhang, C. Tridech, H. Maples, C. Burgstaller, A. Bismarck, and P. Robinson,
“MADE TO ORDER: COMPOSITES WITH CONTROLLABLE STIFFNESS"
(Keynote lecture), ECCM18, Athens, Greece, June 2018.
 M. B. Waili, “FE investigation of interleaved composites for controllable stiffness and
morphing capabilities,” M Eng Final Year Project Report, Department of Aeronautics,
Imperial College London, 2019.