Surface Energy Effect on Damage Evolution in a Viscoelastic Nanocomposite

In this article, the surface energy effect on damage evolution in a linear viscoelastic material filled with second phase nano-particles is studied. Because of the difference in mechanical properties between the matrix material and second phase particles, the progressive debonding of particle-matrix interface may occur under high stress triaxiality, and hence the damage evolution may be described by the nucleation and growth of these debonded voids. In order to study the surface energy effect on this kind of damage evolution, an energy criterion of interfacial debonding under spherically symmetrical loading is proposed, and an expression of the growth of debonded voids in a viscoelastic matrix material is derived, in which the effect of surface tension is also taken into account. Thus, a macroscopic constitutive model of the considered nanocomposite is presented. It is shown that the overall mechanical properties of such a nanocomposite are size dependent, due to the existence of the surface/interface energy effect.