A Simple Engineering Estimate of the Fatigue Notch Factor of Arbitrary Stress Concentrators

In fatigue life estimates, the fatigue stress endured at the hot spot is usually higher than what is predicted by the elastic stress concentration factor. Recently, Neuber's and Novozhilov's approaches of introducing an effective stress by averaging the actual stress field over a characteristic microstructural length have experienced a reappraisal. The present contribution aims at complementing these recent proposals by a mathematically simple engineering assessment of arbitrarily shaped notches, resulting in a closed‐form expression for the fatigue notch factor. The limits of validity of the solution are discussed. In fatigue life estimates, the fatigue stress endured at the hot spot is usually higher than what is predicted by the elastic stress concentration factor. Recently, Neuber's and Novozhilov's approaches of introducing an effective stress by averaging the actual stress field over a characteristic microstructural length have experienced a reappraisal. The present contribution aims at complementing these recent proposals by a mathematically simple engineering assessment of arbitrarily shaped notches, resulting in a closed‐form expression for the fatigue notch factor. The limits of validity of the solution are discussed.