Measures of Circularity for Shell Structures

Abstract

Most design codes for circular shell structures include a limit on out-of-round imperfections. However, commonly used measures of out-of-roundness fail to identify shapes that have constant diameter but are not circular. It is shown that out-of-roundness imperfections that take these forms can significantly affect the strength of nominally circular shell structures. An alternative measure of out-of-roundness is proposed that captures all out-of-round shapes, gives the same measure of out-of-roundness for elliptical structures as currently used measures, and is easy to apply.