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In aerospace structures, the increase of mechanical performance of materials such as Carbon Fiber Reinforced Polymers
(CFRPs) is always a key goal. In parallel, there is a constant demand for multi-functional solutions that provide
continuous, integrated damage monitoring in an efficient and cost affordable way. Structural Health Monitoring systems
are crucial for a variety of aerospace applications where safety, operational cost and the maintenance have increased
significantly. The Electrical Resistance Technique (ERT) as a promising damage monitoring technique uses the CFRP
materials themselves as inherent damage sensors. Currently method's medium sensitivity does not allow the
identification of early damage stages requested for a potential application. By using highly conductive carbon-nanotubes
as filler material into the epoxy matrix of CFRP is expected to increase the sensitivity of the method, allowing for wider
field of applications. In addition, it is expected that the introduction of CNTs into the polymer matrix of CFRP laminates
will increase the overall mechanical and electrical performance of the composite. This double role of the CNTs is
investigated in the present study. Quasi-static tensile, cyclic loading-unloading-reloading with increase load level at each
loading cycle and tension-tension fatigue tests with parallel monitoring of the longitudinal resistance performed on
CFRP laminates with various contents of CNTs in the epoxy matrix showed that matrix cracking and fiber breakage
caused resistance to increase irreversibly. Although the individual damage mechanisms could not be easily distinguished
the overall damage state can be reliably characterized. Moreover significant increase in the fracture resistance was
shown, for both Mode I and Mode II tests in the case of CNT doped laminates, compared against the reference laminate
where neat epoxy matrix was used. Finally, low velocity impact tests showed that the CNT doped laminates appear to
have reduced damage area based on C-Scan evidences.
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