Moisture-induced cracking in a flexural bilayer with application to historical paintings

Crack channelling in a brittle, flexural bilayer, composed of coating adhering to substrate finite thickness, is addressed for the case uniform moisture content (or temperature) variation. The linear stress profile within may lead three different fracture mechanisms, which are crack with delamination absent, length, and unbounded extent. Failure mechanism maps illustrate dependence active mechanism, corresponding critical stress, upon stiffness mismatch between layers ratio interfacial toughness toughness. Although results applicable bilayers wide range applications, study focuses on prediction historical paintings. significance bending bilayer explored by comparing characteristics simply-supported, those rigidly supported that constrained against bending. These two systems representative framing techniques commonly used paintings, simply-supported reflecting regular wooden panel can bend freely, characterizing does not as result cradle additions several horizontal members orthogonal cross-pieces. Independent type technique applied, it shown be avoided paintings when exceeds mode I paint layer. Under these conditions flaking occur visual appearance painting preserved. failure constructed this provide useful tool museum conservators identify acceptable indoor humidity temperature variations such do degrade combination delamination.