Elastic Parameter
Mechanical resistance to internal sliding between the layers of a thick paperboard sheet determines its performance under bending loads. The rolling shear modulus defines the stiffness of the material when subjected to shear forces that run parallel to the surface of the board. This property is particularly important for multi-ply boards where the inner plies often experience the highest shear stresses during creasing and folding operations.
Failure Mode
Creasing and die-cutting demand that the paperboard deforms without cracking on the tension side or buckling on the compression side. The rolling shear modulus predicts whether the board will delaminate during these severe folding operations, which are common in carton converting. If the shear stiffness is too low, the plies will slide too easily and cause bulging creases that ruin the appearance of retail packaging.
Converting plants monitor this variable to adjust their scoring machinery and avoid expensive rejects on the packaging line.
Mechanical Determination
Laboratory instruments measure this property by applying a shear force across the faces of a bonded specimen. This testing requires precise transducer calibration to capture the minute displacements before the fiber bond ruptures. Engineers use these values to refine their finite element models of packaging behavior.
