A Discussion about Double Notches on View Point of Stress Concentration Factor

Abstract

Stress concentration factor at the root of double notches was calculated in a finite width plate specimen. The second notch was located at the root of the first notch. The radius ratio of second notch to first notch was assumed to be less than 0.3. In this study, approximation method of stress concentration factor of double notch was examined. The stress distribution was calculated by the 2-dimensional program based on body force method. The calculation was performed for the specimens with center notch, double edge notches and single edge notch. Three different stress concentration factors, that is, Kt, BFM for direct calculation of the specimens, Kt, double, for approximation by the double-notch concept, and Kt, equi for approximation by the equivalent notch concept, were calculated. Then the values of those stress concentration factors were compared. An accuracy of approximation of Kt, BFM by Kt, double or Kt, equi was examined. In all calculation cases, Kt, BFM can be approximated within 10 % error by Kt, double. However, where the ratio of notch root radius of second notch to first notch was less than 0.1, Kt, BFM cannot be approximated by Kt, equi within 10% error.