Accelerated aging
Accelerated aging is testing that uses aggravated conditions of heat, humidity, oxygen, sunlight, vibration, etc. to speed up the normal aging processes of items. It is used to help determine the long-term effects of expected levels of stress within a shorter time, usually in a laboratory by controlled standard test methods. It is used to estimate the useful lifespan of a product or its shelf life when actual lifespan data is unavailable. This occurs with products that have not existed long enough to have gone through their useful lifespan: for example, a new type of car engine or a new polymer for replacement joints. Physical testing or chemical testing is carried out by subjecting the product to representative levels of stress for long time periods, unusually high levels of stress used to accelerate the effects of natural aging, or levels of stress that intentionally force failures (for further analysis). Mechanical parts are run at very high speed, far in excess of what they would receive in normal usage. Polymers are often kept at elevated temperatures, in order to accelerate chemical breakdown. Environmental chambers are often used. Also, the device or material under test can be exposed to rapid (but controlled)