Structural Failure
The sudden lateral deflection of a box panel under vertical loading marks the transition from stable compression to catastrophic structural collapse. In secondary packaging, container wall buckling represents the primary cause of warehouse stack failure, where the loaded cartons fail before reaching their expected compression limit. The phenomenon occurs when the applied compressive load exceeds the critical bending resistance of the paperboard panels.
Stress Analysis
Structural stress concentrates near the vertical corners of a corrugated box, while the central regions of the panels carry less load. When container wall buckling initiates, the load shifts from the center of the panel toward the stiffer corners, accelerating the degradation of these critical support zones. High-resolution deformation testing shows that board caliper and bending stiffness are the primary factors determining the onset of this failure mode.
Prevention Method
Optimizing the linerboard weight and flute profile helps to increase the bending stiffness of the panels, which delays the onset of lateral deflection. Board designers use the McKee formula to estimate the compressive strength of boxes, which directly incorporates panel dimensions and bending stiffness to predict buckling thresholds. This predictive modeling allows manufacturers to select paperboard grades that balance cost with structural safety.
Selecting a higher-caliper board with identical basis weight provides a cost-effective way to improve buckling resistance without adding excess fibre.
