Until the 2000 Edition of API-579, the geometries for which a complete set of stress intensity factor influence coefficients (G~i~) existed was limited.  To bridge that gap, many analysists used the G~0~ and G~1~ coefficients for flat plate geometries to represent cylinders.  Because the cylindrical geometry contained additional stiffness due to curvature, it was assumed that the plate geometry was conservative.

 

 Since 2007, extensive sets of G~i~ coefficients have been published for plates, cylinders and spheres, based on finite element models.  These coefficients for a flat plate and cylinders have been curve fit and are available in Appendix A of the ASME Boiler and Pressure Vessel Code, Section XI.  The Appendix A equations used for this comparison are contained in the paper.  This paper compares the G~0~ coefficients at the deep point of semi-elliptical flaws from a plate to those from circumferential flaws in a cylinder (ID and OD) to confirm the conservatism of the G~0~ coefficients from a plate.  The results show that the conservatism of the plate G~0~ coefficients depend on the inside radius to thickness ratio (R~i~/t), flaw depth to thickness ratio (a/t) and flaw depth to surface length ratio (a/l).


Comparison of Stress Intensity Factor Coefficients for Plates and Cylinders Under Membrane Stress

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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