Evaluation of fatigue damage parameters for Ni-based super alloys Inconel 825 steel notched specimen using stochastic approach

摘要

In the present investigation, temperature dependence fatigue strength behavior of Ni-based Inconel 825 super alloys is investigated. Based on the experimental results, different S-N models have been derived and a suitable model for the prediction of fatigue strength has been proposed. An inverse power as well as exponential relation between the fatigue strength and absolute temperature is demonstrated. The proposed models are used to predict the fatigue life using the well-known Palmgren-Miner rule. Based on high to low load steps and low to high load steps datasets under identical test conditions, the damage constant of Miner rule is stochastically modeled for fatigue life prediction. The statistical model is developed combining the probabilistic nature of Miner rule damage constant and stress-life-temperature relation. It is also validated through sets of experimental data and found to be useful in reliability-based design.