A new nonlinear fatigue damage model based only on S-N curve parameters

Several fatigue damage models have been proposed in the past to overcome the shortcomings of the commonly used Miner's rule. However, application of these models requires either the determination of material parameters or modifications to the S-N curve of the material. To overcome these problems, a new fatigue damage model is proposed in this paper. The proposed model is based on the commonly available S-N curve parameters of the material and does not require any additional material parameter determination or S-N curve modification. The validity of the proposed fatigue damage model is confirmed by comparing the experimentally derived damage evolution curves for C 45 and 16 Mn steel. The proposed model gives a better agreement with these experimental results compared to previous models. A new damage transfer concept is also proposed for a more accurate estimation of fatigue life and is verified with experimental results for fatigue lives of six materials. The predicted fatigue lives are in better correlation with experimental results compared to Miner's rule and other recently proposed models. Finally, the application of the proposed model is illustrated by a case of welded joints. The model is applied to butt and fillet welded joints and the predicted fatigue lives show better agreement with experimental results compared to earlier models. The maximum and average deviations from the experimental results are 20% and 9% respectively. It is concluded that the proposed model can be easily applied by practising engineers for an accurate prediction of fatigue life.