impactfatigueinducedcan

Impactfatigueinducedcan is a term used in failure analysis to describe a metal container that fails due to a combination of impact loading and cyclic fatigue. It commonly applies to aluminum or steel cans used for beverages, aerosols, or other pressurized contents, where repeated or severe impacts create stress concentrations that promote crack initiation and growth in thin-walled sections.

Mechanism: When a can is dented or dropped, residual stresses accumulate at the dent edge and at existing surface flaws. Under subsequent handling or pressurization cycles, these areas experience cyclic stress that drives crack initiation. Microcracks propagate with each impact or vibration, often starting at pits or inclusions and controlled by the material’s fatigue strength and the can’s wall thickness. If a crack reaches a critical size, the integrity of the can is compromised, potentially leading to rupture or leakage, especially if internal pressure is high.

Materials and testing: Most impact-fatigue failures are reported in thin-walled aluminum beverage cans and steel tins, though any metal can susceptible to denting is at risk. Detection and study employ nondestructive testing such as dye penetrant inspection, ultrasound, and X-ray, along with fracture surface analysis. Engineers use drop tests, cyclic impact testing, and finite element modeling to assess fatigue life and to identify design weaknesses.

Prevention and design: Reducing risk involves improving dent resistance through thicker walls, larger radii at corners, and controlled residual stresses; using protective coatings or liners; minimizing stress concentrators; and employing packaging solutions that reduce impact exposure during transit. Incorporating venting or anti-burst features in pressurized cans can mitigate rupture risk pending crack growth. The term itself is not a standard designation in most packaging codes, and in formal practice the phenomenon is described as impact-induced fatigue failure in cans.