Stress analysis of V-notches with and without cracks,with application to foreign object damage

Abstract

Gas turbine engines can be subject to ingestion of small hard particles, leading to foreign object damage. This can take the form of sharp V-notches in the leading edge of blades and there is a need to predict the initiation and propagation behaviour of fatigue cracks growing from the base of the notch. The notch geometry is quite extreme and is not normally covered in standard references for notch stress concentration factors. Similarly, stress intensity factor solutions for this geometry are not widely available. This paper uses the dislocation density approach to solve the two-dimensional elastic problem of a V-notch with a radiused root. Stress concentration factors are found for the notch itself, and stress intensity factors are determined for cracks growing away from the notch for cases of applied and residual stress distributions. Comparisons are made with existing notch solutions from the literature.