JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 61
Testing nano-scale reinforced resin-infused carbon fibre composites
by C-scan inspection and testing according to BS EN ISO
18352:2009. Doing this with an Imetrum UVX Flexi system
, as an alternative to applying strain gauges, speeds up the
test process and makes multiple measurements easier, whilst
still being sufficiently accurate. A two-camera setup enables
front and back faces to be measured, to identify any degree of
bending during compression testing. A full-field 2D surface
strain map can also be produced using specialist lensing to accommodate any optical effects caused by material buckling.
This can provide additional diagnostic information to help
identify areas of high and low strain and likely failure initiation points. Figure 1 shows a typical test setup for compression after impact.
DCB testing was also carried out to determine and compare fracture toughness in the materials. DCB testing can be
time-consuming, requiring manual identification of the crack
tip location which can subjective. The research team chose to
use an Imetrum UVX Flexi system to make this test and subsequent analysis easier by providing a live measurement of crack
length during the test and logging a corresponding record of
load. Figure 2 shows a Video Gauge™ software screen shot and
the DCB crack length gauge in operation.
Of particular importance is the improved compression after
impact performance, which is a key property considered when
selecting for composite aerospace structures. Such materials
could facilitate significant reductions in structural weight and
manufacturing costs for future aerospace structures.
Using the Imetrum UVX Flexi system as an alternative to
strain gauging is saving Cardiff University time and money by
reducing the need for strain gauges, as well as providing additional diagnostic information (measuring more points), providing full field strain maps and automating the measurement
of crack lengths in DCB specimens.
Panels and representative components were successfully manufactured, inspected and tested. The manufactured composites were found to exhibit up to 50% greater CAI strength, inplane shear and fracture toughness properties when compared
to traditional composites.
www.estaca.fr - http://laum.univ-lemans.fr
The test results are reported in Figure 3. In most cases, improvements in properties were observed when compared to
a standard carbon fibre epoxy composite, with the exception
of interlaminar shear strength. Neither nano-reinforcement
type is seen to perform consistently better than the other with
graphene outperforming for compression after impact and
tensile strength, and carbon nanotubes for in-plane shear and
An important requirement for any manufacturing process is
scalability. A process must be scalable to produce useful component parts - in this case aimed at aerospace applications.
The ability to functionalise nano-fillers, incorporate and disperse them consistently into a resin whilst still retaining a useful viscosity is a challenging problem.
The process developed in this project was used to produce an
8kg batch of 0.5 wt.% FLG functionalised resin for panel and
stringer manufacture. Figure 4 shows an image of the completed panel with bonded skin and I-section stiffeners. C-scan
post manufacture confirmed the good quality of the component parts.
It has been demonstrated that a plasma functionalisation process combined with high shear mixing and a resin infusion
technique can be used to produce nano-reinforced carbon
fibre composites at the component-scale level with clear potential for substantial improvements in mechanical properties.
 M.J. Eaton, W. Ayre, M. Williams, R. Pullin and S.L.
Evans, Nano-reinforcement of Resin Infused Carbon
Fibre Laminates using Carbon, 16th International
Conference on Experimental Mechanics, Cambridge, 7-11
 M.J. Eaton, W. Ayre, M. Williams, R. Pullin and S.
L. Evans, Developing component-scale hierarchical
composites using nanocarbons, 20th International
Conference on Composite Materials, Copenhagen, 19-24
 CARHAY2011. http://cordis.europa.eu/
 Imetrum. http://www.imetrum.com
The Mechanical and Structural Performance Group is based in the
faculty of Engineering at Cardiff University:
Haydale has developed a patented proprietary scalable plasma
process to functionalise graphene and other nanomaterials:
Imetrum is a world leader in the field of camera-based, non-contact precision measurement: www.imetrum.com
No112 April - May 2017
/ jec composites magazine