Plasticity Threshold
Material deformation theory provides a mathematical framework for predicting when solid paperboard begins to undergo permanent, irreversible change under combined pressure. Drucker prager shear yield defines the limit where a substrate transitions from elastic to plastic behavior while accounting for the effect of hydrostatic stress. This model acknowledges that paperboard becomes stronger as it is compressed, unlike simpler metallic models that ignore volume changes.
Failure Calculation
Determining the point of failure involves calculating the invariant stress states within the board layers during a converting process like scoring or folding. Implementation of drucker prager shear yield allows engineers to simulate how a carton wall will bulge or collapse when subjected to heavy stacking loads in a cold storage warehouse. Accurate simulation requires precise input regarding the internal friction angle and the cohesion of the fiber matrix.
Converting Application
Die cutting and creasing rely on controlled damage to the material structure to ensure clean folds without unwanted cracking. When drucker prager shear yield is reached during the creasing step, the board delaminates internally to create a flexible hinge. This localization of damage ensures that the final box maintains sharp corners and accurate dimensions on an automated filling line.
If the yield point is not reached correctly, the board may snap or fail to fold at the intended line. Poor control over this transition leads to jammed machines or skewed secondary packaging.
