As the life and reliability capabilities of cryocoolers have improved there has been a corresponding evolution of user requirements. Tactical applications routinely require operation in excess of 10,000 hours; space-borne applications require operational life of >10 years. Demonstration of these long lifetimes provides a substantial challenge. Previous treatises have discussed means of addressing specific aspects of reliability via accelerated life testing. This paper provides a review of documented accelerated test methods as well as test methods that may be considered for non-wear related failures. A review of common life-limiting features of cryocoolers is provided, including: seal wear, flexure fatigue, gaseous and particulate contamination, fretting failures at interfaces between non-moving/moving components and random failures. A recommendation for accelerated assessment of the lifetime and reliability related to each limitation is presented. The result is a compilation of test methodologies that may be tailored to users' and designers' needs. This approach offers the potential of providing a realistic assessment of operational life without incurring the cost and schedule associated with operating multiple cryocoolers to failure over a multi-year period.
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