Availability Analysis of Systems with Suspended Animation

In many practical cases, during a system failure or downtime, all non-failed components are kept idle to eliminate further damage to the system. This phenomenon is known as suspended animation (SA) because the aging process of the non-failed components is suspended. Suspended animation introduces dependencies among the component states. Therefore, we cannot calculate the system availability using the methods that are used to calculate the system reliability. In this paper, we provide a simple and efficient method to compute the availability indices of repairable systems subject to suspended animation. Using this method, we propose efficient algorithms for k-out-of-n systems. An important aspect of the proposed method is that it is not restricted to exponential failure and repair distributions. This method is also applicable for certain imperfect repair situations. Further, it can be applied to any system configuration with embedded hierarchical k-out-of-n subsystems subjected to suspended animation.