Creep is the deformation of a material occurring with time due to an externally applied constant stress. For cushioning materials specifically, it may be defined as the change in thickness of a cushion under static compressive load over a period of time.
It is also referenced as a procedure designed to determine the resistance of a shipping container to a vertically applied constant load for either a specified time or to failure. The test method may also be used for palletized or unitized load configurations.
Another test method covers determining the resistance of an empty paper corrugated shipping container to a vertically applied constant compression load for a specified time. The test method may also include palletized or unitized loads made of such containers. The boxes are tested in the orientation that they are most likely to be stacked in a unitized or palletized load.
Finally, the term “creep testing” may refer to test methods or procedures for determining the ability of packages to withstand internal pressurization. The creep test maintains a specified pressure for a specified time or until the package fails.
(20) Creep Test fixtures