ABSTRACT
Although natural (outdoor) test is time-consuming and limited to only special levels of stressors (depending on the geographical situation), but its results could be useful to make a comparison with the corresponding results obtained from ADT especially if no field data are available. Such comparison might be used to recognize whether a physical property could be a reasonable representative of product quality over time in service (e.g. (Bo, Gerofi, Visconte, and Nunes 2007)). One of the most probable reasons of deviation of an ADT (from natural test) is due to its excessive high stress levels than normal (e.g. (Richaud, Farcas, Divet, and Benneton 2008;Yang and Ding 2006)). For more realistic results, degradations of physical properties for test samples could be achieved by a combination of accelerated and natural testing (e.g. (Fekete and Lengyel 2005)).
