Dynamic Strain Rate Modeling for Multi Ply Boxboard under Rapid Compression
Dynamic strain rate modeling predicts multi-ply boxboard Z-direction compression and interlayer shear collapse during high-speed converting and package drops.
Fiber Network Collapse
Structural Failure
Compressive forces can cause the individual pulp fibres in paperboard to flatten and lose their load-bearing capacity. This microstructural transition is known as fiber network collapse, and it represents the irreversible loss of bulk and stiffness within the sheet. It occurs when the open space between the bonded fibres is crushed.
Compression Impact
During the manufacturing and converting processes, excessive calendering or high-pressure printing nip rolls can trigger this failure prematurely. The fiber network collapse reduces the thickness of the board and lowers its bending resistance, making the final box more susceptible to creasing and bulge. Once the network is compromised, the material cannot return to its original shape or recover its lost strength.
This mechanical degradation is especially severe in recycled paperboards that have shorter and weaker fibres.
Moisture Sensitivity
Exposing paperboard to high relative humidity weakens the hydrogen bonds that hold the fibre skeleton together, lowering the threshold for this physical breakdown. The fiber network collapse occurs at much lower loads when the board moisture exceeds twelve percent. In humid storage rooms, the moisture-laden fibres soften and buckle under the weight of stacked pallets.
Preventing this failure requires the selection of raw materials with high-density fibre bonding or the application of protective moisture barriers.