Influence of auxeticity of reinforcements on the overall properties of viscoelastic composite materials

This work aims to analyze the damping response of viscoelastic composite reinforced by elastic auxetic heterogeneities by means of micromechanical modeling. The linear viscoelastic problem can be transformed into the associated elastic one via the Carson-Laplace transform (C-LT). Loss factors are taken into account by the introduction of the frequency-dependent complex stiffness tensors of the viscoelastic phases. The micromechanical formalism, based on the kinematic integral equation, leads to the computation of effective storage modulus and its associated loss factor in the quasi-static domain. The possibility to enhance viscoelastic (VE) properties of a polymeric material such as PVB is examined through several mixing configurations. Thus, the use of elastic auxetic heterogeneities is analyzed in comparison with classical elastic and viscoelastic reinforcements. The model predictions for VE phases, confirm the possibility to improve the global material stiffness. Also, it is shown in the particular case of elastic and spherical heterogeneities, by a proper choice of phases' stiffness ratio Q, that auxetic reinforcements represent a good compromise to have simultaneously enhanced stiffness and loss factor response in composite materials