Volume 3, Issue 8 (September 2006)
Effect of Bauschinger-Modified Autofrettage Residual Stresses on Cannon Fatigue Life
Fatigue modeling of autofrettaged cannons is described, including design modifications for steel vessels with 1170 MPa strength. A similar Ni-Cr-Mo-V steel but with 1360 MPa strength is planned to reduce weight. A new design must include modeling of the hoop compressive residual stress at the inner diameter, that has significant control of both the yield pressure and fatigue life. Results shows good agreement between measured lives from full-size cannon tests and calculated Paris lives including a Bauschinger-reduced material strength. Paris life calculations show effects of three important pressure vessel variables: initial crack size, extent of autofrettage, and outer-to-inner radius ratio.