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The large diffusion of structural parts made of carbon fibres reinforced polymers (CFRP) in the aerospace and
automotive sectors has highlighted the importance of developing hybrid multifunctional materials characterised by
improved mechanical properties and coupled with non-structural features. Indeed, while due to their high specific
strength and light weight, composite systems are characterised by very high mechanical properties in the in-plane
direction, their intrinsic layered structure makes them very susceptible to low-velocity impacts resulting in Barely Visible
Impact Damage (BVID) that can lead to the critical failure of primarily structures. Based on these premises, the
development of a multifunctional hybrid system can overcome this drawback by tackling this issue from two different
points of view, enhancing the total reliability of light-weight composite parts in order to improve fuel efficiency and
optimise the footprint of new generation aero-structures. Indeed, by including an additional metallic phase within the
structure of a traditional laminate it is possible to develop a smart multifunctional system in which the hybrid phase acts
simultaneously as a reinforcement to enhance the out-of-plane properties of the material and as an intelligent embedded
sensor system able to communicate information about the health status of the part and detect impact events or critical
loads.
This work is focused on the design, manufacturing and testing of a hybrid CFRP (H-CFRP) in which the hybridisation is
obtained by including an array of Shape Memory Alloys (SMA) or Copper wires within the laminate. The electrical
properties of the hybrid network is exploited to design a smart sensing system which can be interrogated to monitor the
load distribution on the part and detect critical solicitations in critical points. The low-power system, controlled by an
Arduino microcontroller, is able to monitor the integrity status of the part using each wire as a linear probe to scan
complex structures at a certain frequency, measuring the local change in the electrical resistance from which it is
possible to build a map of the stress distribution. The position of the metallic network along the laminate’s thickness was
determined by analysing the response of different configurations of hybrid samples subjected to Low Velocity Impacts
(LVI) in order to optimise the design of the H-CFRP and enhance the energy absorption. Using the same Arduinocontrolled
Multiplex the smart wires array was exploited as heat source to scan the sample inner structure and
monitoring the variation of the superficial apparent thermal variation with an Infra-Red (IR) Camera, a simulated
delaminated area was detected.
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