Prior to system integration testing, assemblies and subsystems are frequently subjected to tests that seek to surface failure modes associated with a specified set of environmental conditions. The induced environmental stresses are often elevated above normal usage levels to shorten the test duration necessary to surface the failure modes. One natural question that arises is how long should the unit under test be subjected to the environmental conditions. Once we have surfaced a sufficient set of failure modes, our resources should be redirected toward eliminating the surfaced modes and toward testing additional assembly (or subsystem)/environment combinations of interest. In this paper, we propose a metric for use in deciding when sufficient testing has been accomplished for a complex assembly or subsystem in a specified environment. The proposed metric utilizes the first occurrence times of the observed problem failure modes. We propose a related metric for the discrete case where test duration is measured in terms of trials or duty cycles.

This content is only available as a PDF.
You do not currently have access to this content.