On statistical and information-based virtual age of degrading systems

Two approaches to defining a virtual age of a degrading system are considered. The first one is based on the fact that deterioration depends on the environment. In a more severe environment deterioration is more intensive, which means that objects are aging faster and therefore, the corresponding virtual age is larger than the calendar age in a baseline environment. The second approach is based on considering an observed level of individual degradation and comparing it with some average, ‘population degradation’. The virtual age of the series system is defined. Several illustrative examples are considered.