| Notch-tip strains and fatigue crack initiation life in an SAE compact tension keyhole specimen have been estimated under plane stress and plane strain conditions using three local stress-strain methods--Neuber's rule, Improved Neuber's rule and Equivalent Strain-Energy Density method. The estimates obtained are compared with the experimental results from the literature to evaluate the capabilities of these local stress-strain methods.;It was found that Neuber's rule overestimated the notch-tip strains and grossly underestimated the fatigue crack initiation life. The energy approach was found to be the best. Improved Neuber's rule estimated strains as well as fatigue lives far better than Neuber's rule. The strain estimates were found to be within a range of 10 to 12% and the fatigue life estimates were within 15 to 20% of the corresponding estimates by energy approach.;It was concluded that the improved Neuber's rule can effectively replace conventional Neuber's rule and, owing to its simpler calculations, can also be used in place of the intricate energy approach. |
