A new approach to the positive mean stress diagram in mechanical design

Abstract

The Gerber, modified Goodman, Soderberg, Bagci, ASME-elliptic and Clemson diagrams are proposed for estimating mechanical element fatigue strength under positive mean and alternating stresses. However, all of these diagrams are either conservative or have fields containing stress greater than yield strength of mechanical element materials. The aim of this study was to propose a new simple diagram with an exponential power k for various types of mechanical element materials. Exponential power k values of steel and Al-alloy materials were about 0.80 and 0.45, respectively. The proposed diagram (Sekercioglu line) had a minimum average absolute deviation (X m) of 8.56 %, lower than the Bagci, ASME-elliptic and Clemson diagrams. The Sekercioglu line can be successfully used in fatigue design processes because of its simple structure and its less conservative nature. © 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.