The examination of stress transfer phenomena at the interface of composite materials
has long been a focal point in mechanical engineering. This investigation involves an
in-depth study at these contact surfaces, aiming at exploring the mechanisms
governing stress distribution and exchange across the distinct phases. In order to
exploit the interaction between diverse materials within each phase, leveraging
their complementary attributes, the bond behaviour analysis would help to
optimize the overall performance and functionality of the composite material.
Many documents are available in literature providing efficient computational
simulations, reproducing the non-linear bond behaviour at the interface
contact. Nevertheless, those models are sensitive to underlying assumptions and
modelling choices, which can significantly influence the results. The aim of
this research is to include all the modelling assumptions in the formulation
of an elastic and a dissipation energy functionals within the context of a
hemi-variational principle. For the sake of simplicity, the interface interaction is
reduced to a single damage-elasto-plastic spring in series to an elastic one,
which represents the deformation of one of the two phases. The irreversible
formulation was developed considering the following steps: (i) definition of
two irreversible kinematic descriptors, i.e. a damage index and a plastic
displacement, (ii) assumption of an energy functional and (iii) postulation of a
hemi-variational principle. Governing equations are therefore derived, including the
Karush–Kuhn–Tucker conditions that predict the evolution of irreversible damage
and plastic descriptors. The suitability and reliability of this model have
been verified comparing numerical and experimental results for the pullout
tests carried out for different systems of a single steel cord embedded in an
inorganic mortar matrix. Likewise, the evolution of damage and plasticity is
calculated. Finally, a parametric investigation is implemented to evaluate
to what extent a single factor of the energy functional affects the overall
performance.