Models for saturation damage state and interfacial shear strengths in multilayer coatings

Abstract

a b s t r a c tThe present work investigates the saturation damage state of a two-layer coating on a substrate (layer 1/layer 2/substrate) under uniaxial tensile loading in order to derive expressions for the interfacial strength between layer 1 and layer 2, and between layer 2 and substrate. It is based on experimental data on specimens where layer 1 is an inorganic film, layer 2 is an organic coating and the substrate is a polymer. The analysis is relevant to the cases where layer 1 cracks first, followed by layer 2, in which cracks appear due to stress concentrations caused by the cracks in layer 1. It considers the cases where at least one interface is completely yielded with shear stress equal to the interfacial shear stress, and where the crack density in layer 1 is equal to or higher than the crack density in layer 2. The possible situations depend on the relative shear strengths between layers 1 and 2 and between layer 2 and the substrate. The interfacial shear strength between layer 1 and layer 2, and between layer 2 and substrate are derived for elastic and yielded stress transfer cases and found to frame experimental values obtained with single-layer coatings.

Prediction of crack density and electrical resistance changes in indium tin oxide/polymer thin films under tensile loading

“…We note that the evolution of the damage parameter for crack density in our model behaves similarly to the evolution of crack density as reported in the literature (Cairns et al. 2000; Kim and Hong, 2009a, 2009b; Leterrier et al., 2004, 2010a, 2010b; Peng et al., 2011; Pinyol et al., 2009). From this observation, it seems reasonable to use a power law relationship to obtain the crack density, n , as a function of the damage parameter.…”

Numerical implementation of anisotropic damage mechanics

“…Fracture mechanics models are available for predicting 2D cracking of a single, linear elastic layer on a linear elastic substrate . The potential applications of damage mechanics could include cracking of multiple brittle layers, effects of inelastic substrates, or 3D cracking in biaxially loaded films …”

Nanomechanical study of polymer‐polymer thin film interface under applied service conditions

“…It is expected that interface damage first since the interface is the weakest zone compared to individual properties of film and substrate. The intensity of cracks is the direct representation of damage at the interface because of delocalization of strain . The inset shows the enlarged view of crack developed after service loads S 1 and S 2 were applied.…”