Numerical Study on Stress Concentration Effect in Rapid Evaluation of Fatigue Limit through Temperature Evolution

The technique for rapid evaluation of fatigue limit using infrared thermography has been developed and paid much attention recently. However, the enhancement of reliability of this technique is demanded for practical application in industries. This study is conducted to verify the effect of stress concentration on fatigue limit evaluation through numerical simulation. Temperature evolutions of stainless steel specimens with different notches are simulated by 3D elasto-plastic finite element analysis. It has been shown that the fatigue limit evaluation based on the temperature evolution is essentially explained by plastic energy dissipation, and that the temperature evolution should be measured after a sufficiently large number of cycles so that plastic shakedown is achieved. It has been remarked that the fatigue limit is overestimated if the spatial resolution of infrared thermography is not fine enough to measure the temperature evolution at the stress concentration site.