Effective interfacial thickness in dissimilar materials through nanoindentation

The nanoindentation technique is used to quantify the interfaces between dissimilar materials. The interfaces can be generally referred as to the transition regions in polymers due to environmental aging, or the regions between fibers and polymer matrix in composites, or other similar situations. It is proposed to use a nanoindenter equipped with small spherical tip to cross-indent the interfaces of dissimilar materials. The nanoindentation tests were carried out through 3-dimensional finite element simulations with varying properties of the two dissimilar materials, including various combinations of modulus (E₁/E₂), yield strength (σ_y1/ σ_y2), hardening index (n₁/n₂), and the interface sizes (R/T). The mechanical properties are calculated across the interfaces and a quantitative model for predicting the effective interfacial thickness is established.