A continuum damage model for creasing and folding of paperboard

A continuum damage framework is proposed for modelling the delamination process occurring in paperboard during mechanical loading. The main application of interest is line creasing and subsequent line folding used in package forming. To adequately capture creasing and folding, a continuum damage framework that uses a single isotropic damage variable that evolves with the plastic strains associated with out-of-plane shearing is used. The damage evolution is calibrated against folding experiments for a specific reference mesh, and a simple scaling strategy is proposed to reduce the inherent mesh dependency. To highlight the potential of the proposed model, an illustrative 3D example is considered where a paperboard sheet is creased by two plates and folded to resemble the corner of a package.