Accelerated Aging

Accelerated Aging tests are commonly performed to demonstrate that a product (including materials, coatings, packaging, and labeling) can be expected to be stored for a number of years and still function as required. To expedite the effects of time, the product is subjected to temperature and humidity conditions more severe than it would typically experience in its shipping, storage and operational life cycle.

The end goal is to provide confidence that the product will meet its expected lifetime and reliability goals without having to wait an entire life cycle to get results.

Acceleration Rate

The Acceleration Rate (also called the Accelerated Aging Rate, Accelerated Aging Factor or Acceleration Factor) is defined as the ratio of the real-world life-time to the test duration.  The higher the acceleration rate, the less reliable the test is.  For example, a one year accelerated aging test intended to demonstrate a 10 year storage life (acceleration rate of 10), will be much more valid than a one month test at more extreme conditions that is also intended to demonstrate a 10 year storage life (acceleration rate of 120).  There are two reasons for this:

  1. Using more extreme conditions (for example, higher temperatures) in order to increase the acceleration rate can result in failure modes that would not occur in real-life (for example, melting of plastics).
  2. The acceleration rate must be determined from theory or previous experiments on similar products, rather than experiments on the actual product, because that would require that the real-time test be performed and thereby take the time that one is trying to avoid by doing an accelerated test.  To the extent that the actual product acceleration rate differs from theory or experimental data on other products, the size of the error tends to increase with a higher acceleration factor.  For this reason, testing standards and regulatory requirements impose maximum accelerated aging rates that can not be exceeded when testing critical products such as medical products that must remain sterile while in storage.

The best understood and experimentally validated acceleration rate, and therefore the one that is most commonly used and accepted, is the Arrhenius Equation which states that each 10C increase in temperature results in a doubling of the acceleration rate.  For example, if the normal product storage temperature is 25C, the acceleration rate at 35C will be 2, at 45C it will be 4 and at 55C it will be 8.

In conjunction with a package validation test plan (within ISO 11607 guidelines), accelerated aging can generate quick results.  Accelerated aging data is useful to produce a broad understanding of the effects time may have on a product.

Common Accelerated Aging Tests:

  • ASTM F1980: Accelerated Aging of Sterile Barrier Systems for Medical Devices