AN ANALYSIS OF CYCLIC STRESS-STRAIN RESPONSE AND FATIGUE LIFE ASSESSMENT OF NOTCHED CYLINDRICAL COMPONENTS

摘要

The circumferentially notched cylindrical components of annealed copper were cyclically strained under diametral displacement-controlled condition. The localized cyclic stress-strain responses at several locations in the minimum cross section including notch root were calculated by introducing the constitutive equation for analyzing cyclic hardening behavior, which was derived on the basis of dislocation dynamics in the authors' earlier paper, into finite element method. The calculations showed that the mean stress and strain were generated on the minimum cross section under diametral displacement-controlled condition with displacement ratio R= 1.0, and a convex-shaped axial stress distribution produced in first tensile stroke changed into distribution exhibiting the greater stress at the outer-location in the minimum cross section as cyclic hardening process progresses. The equivalent plastic strain range was calculated at the notch root in saturation hardening stage and then this was substituted for the plastic strain range in the Coffin-Manson equation which was determined from low-cycle fatigue test for smooth specimen. The estimation gave the reasonable life prediction of notched component.