ENGINEERING APPLICATION OF EXPERIMENTAL UNCERTAINTY ANALYSIS

Publication in late 1993 by the International Organization for Standardization (150) of the Guide to the Expression of Uncertainty in Measurement in the name of ISO and six other international organizations has, in everything but name only, established a new international experimental uncertainty standard. In this article, an analysis of the assumptions and approximations used in the development of the methods in the ISO guide is presented, and a comparison of the resulting equation with previously published uncertainty analysis approaches is made. Also discussed are the additional assumptions necessary to achieve the less complex ''large sample'' methodology that is recommended in AIAA Standard S-071-1995, Assessment of Wind Tunnel Data Uncertainty, issued in 1995. It is shown that these assumptions are actually less restrictive than those associated with some previously accepted methodologies. The article concludes with a discussion of some practical aspects of implementing experimental uncertainty analysis in engineering testing.