Stress Intensity Factors for Elliptical Surface Cracks in Round Bars and Residual Life Estimation

Marija Blažić
Mirko Maksimović
Ivana Vasović
Yasmina Assoul

This work investigates the behavior of structural components with surface cracks1,2 . The attention is focused on a circular bar with an elliptical surface crack under tension load. The aim of this study is to analyze the influence of the shape and size of cracks at the structural part on the fracture mechanics parameters. Stress intensity factors (SIF) are considered using the finite element method. For that purpose a straight round bar under tension is investigated. Stress intensity factors of elliptical surface cracks in tensile round bars are calculated by using three-dimensional finite element analysis (FEA) models with singular 20-node elements arranged around the crack tip. The graphic and the table review of stress intensity factors are also determined. The stress intensity factors are calculated for various dimensions of surface cracks. These results are used to determine an analytic form of the stress intensity factors that is necessary in crack growth analyzes. Using the derived analytic formulae for the stress intensity factor based on the FEA, a crack growth analysis is carried out.

Key words: fracture mechanics, stress analysis, tension, bar, crack, crack growth, finite element method.