Interface Model
Predictive simulations of material failure rely on a mathematical relationship that describes how surfaces pull apart as stress is applied. Traction separation law defines the force required to increase the distance between two bonded surfaces until they are completely disconnected. This constitutive model is the primary tool for analyzing how adhesives or inter-ply bonds behave in a packaging structure.
Bond Strength
Characterizing the strength of a glue line involves plotting the traction, or force, against the displacement of the two substrates. A typical traction separation law follows a curve that rises as the bond resists movement and then drops as the internal structure of the adhesive or fiber matrix begins to fail. This data allows packaging designers to choose the right glue for specific varnished or coated surfaces.
Simulation Precision
Finite element analysis uses these laws to model the opening of a carton or the failure of a shipping seal. By applying a traction separation law, engineers can predict if a tamper-evident closure will function correctly or if the board itself will tear before the adhesive lets go. This level of detail is necessary for high performance packaging where the speed of the filling line and the safety of the product are paramount.
The model ensures that the bond is strong enough to survive transport but weak enough to allow the end user to open the box without difficulty.
