Machine Direction Strength Theory of Corrugated Fiberboard

Linerboard elements between the corrugations of corrugated fiberboard can be viewed as short wide columns when the fiberboard is loaded perpendicular to the axes of the corrugations. Column ends are elastically restrained by the corrugated medium. A theory of buckling of nonlinear corrugated fiberboard material, with compression perpendicular to the corrugation axes, was developed. This theory is consistent with a previous theory applied to fiberboard with compression parallel to the corrugations. The theory matched strength data of corrugated fiberboard using paper compression strength, extensional stiffness, and bending stiffness data as inputs. The theory was further improved by empirically correcting for interactions between material crush failure and structure buckling failure. The correction equation predicts an optimum form of the linerboard stress-strain curve from initial slope and maximum stress data and predicts an element slenderness that varies with the mode of failure.