Stored System Inherent Availability Optimization from a System of Systems Physics of Failure Perspective

Abstract

Stored systems of systems (SoS) such as weapons systems in magazines and storage depots, spare equipment for nuclear power plants, and other stored SoS can sit in storage for decades before use. Failures that impact inherent availability can result from diurnal temperature cycles and other storage issues. Individual storage locations within a storage facility can undergo different diurnal temperature cycles which can impact time to failure of specific systems within the SoS due to physics of failure mechanisms (e.g.: transistor failure from repeated thermal cycles). Other issues such as test and maintenance cycles; certain stored systems being the favored extended test system or in the case of weapons systems used on aircraft, favored sortie systems; and other SoS-specific issues can contribute to reduced inherent availability. This paper presents a method of optimizing contributors to inherent availability from a SoS perspective, and using both individual system failure data and SoS cost information. The result is a stored SoS that is optimized to either meet service life requirements, or a stored SoS that is optimized to extend service life beyond the design basis, or a stored SoS that is optimized to increase inherent availability while meeting service life requirements. A case study of a stored SoS weapons system for aircraft is presented to illustrate the method.