Simplified estimation method of inelastic stress / strain concentration at notch root

Abstract

The Nueber"s rule which is a method widely used for estimating the elasto-plastic stress/strain concentration at notch tends to overestimate the strain concentration in general yield condition. This paper proposes to modify the application procedures of the Nueber's rule to improve the shortcoming. The modified procedures defined the nominal stress and strain by the sectional averaged-Mises equivalent stress and strain in order to take account of the multiaxial stress state in the notched section. This paper also describes the extensional application of the modified Neuber's rule to the creep loading and the deformation-controlled loading conditions which are important in the life evaluation of high temperature components. The effectiveness of the propsoed procedures are verified by the inelastic finite element analyses for notched plates. As the result, it is shown that the change of creep stress/strain concentaration with time can be estiamted by the method proposed. It can be also applied to the deformation-controlled loading based on the nominal equivalent stress estimated by considering the elastic follow-up behavior of the notched members.