Title:
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Self-healing for structural applications
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The research within the field of self-healing fibre reinforced polymers has been mainly
focused on the development of novel healing chemistries and the application on damage
scenarios where the damage volume and progression is contrived and pre-defined by the
specimen geometry. Even though the potential of recovering the mechanical properties has
been shown, limited amount of examples of the application of self-healing in more complex
loading scenarios are found in the literature.
The overall aim of this thesis is to apply self-healing within a higher complexity loading
scenario resembling industrial relevant applications. Skin-stiffened structures combined with
a vascular healing approach have been selected as the target scenario.
Skin-stiffener debond specimen, mimicking the stress state at the tip of the flange, have been
used to understand experimentally the damage progression under tensile-tensile fatigue. The
damage progression has been manipulated by locally changing the fracture toughness with
interleaves, transverse vascules and an oblique ply structure in order to steer efficiently the
damage into predefined interfaces where the vascules are located. However, only moderate
healing was obtained, reason being the small size of the connectivity between the vascules
and the damage network. In contrast, efficient healing was demonstrated within strap lap and
stringer run-out specimen tested under static tensile loading.
The findings within this thesis suggest that there is a potential to recover damage occurring
within industrial relevant structural applications, having the capacity to reduce conservative
safety margins and therefore permitting to exploit the weight saving potential of fibre
reinforced polymers.
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