Modelling the hygroscopic buckling of layered paper sheets

A model is constructed to treat the hygroscopic buckling of layered rectangular paper sheets. The sheet is assumed to consist of K layers each of which has a thickness that varies with position. Each layer of the sheet is taken to be rectilinearity orthotropic, and both the constitutive constants and hygroscopic coefficients may vary with position in an individual layer. A set of global constitutive relations is developed and is used to derive the generalized von Karman equations which govern hygroscopic buckling and postbuckling behavior.