Durability Test Time Reduction Methods

Laboratory based durability simulation has become an increasingly important component of vehicle system design validation and production release. It offers several advantages over field testing which has driven its adoption in the automotive and military sectors. Among these advantages are 1) repeatability, 2) earlier testing, 3) isolation of subsystems or components and 4) ability to compress and/or accelerate the testing. In this paper we present time-domain methods and techniques adapted, implemented and used at TARDEC to reduce the time required to perform a laboratory durability test of a full vehicle system, subsystem or component. Specifically, these methods approach a durability schedule holistically by considering all events/surfaces, repeats and channels of interest. They employ the standard Generic Stress Life (GSL) approach, utilizing rain flow cycle counting and a minimum-average method of identifying segments of the events which are less severe. The mathematical methods are presented as well as a case study in which the methods are used. The case study illustrates the effectiveness of the compression methods at five different levels of retained severity. Finally, we discuss joining methods and demonstrate that the joining method chosen has an effect on the overall test compression performance and has the potential to either degrade retained severity or lengthen the test.