Structural Failure
Time-dependent collapse of a loaded container occurs under constant compression at load levels far below the initial dynamic failure limit. This phenomenon, termed creep buckling, arises when the paperboard loses its stiffness under continuous stress. It defines the ultimate limit of a carton’s stacking life in warehouse environments.
Load Mechanism
Continuous pressure on a corrugated box causes a slow, permanent deformation of the paperboard walls over time. When creep buckling takes place, the flutes of the board gradually bend and the vertical panels bulge outward until they can no longer support the weight. The rate of this deformation depends on the grade of paperboard used and the magnitude of the static load applied during storage.
Environmental Influence
Moisture changes in the surrounding air accelerate the physical failure of paper-based packaging under stress. Because cellulose is highly sensitive to humidity, the rate of structural movement increases dramatically when the material absorbs water from the environment. This means that a box that holds its load perfectly in a dry warehouse might fail in a humid transit container.
Proper selection of raw materials and sizing agents helps extend the lifespan of cartons subjected to long-term storage under changing weather conditions.
