Monitoring of Stress Concentration at Circular Holes Caused by Cyclic Loading

摘要

The direct observation was made of the stress concentration around circular holes as a cause of fatigue failure by cyclic loading. The change of surface conditions of carbon steel plates with 3 circular holes subjected to cyclic loading with the load ratio 0 was observed. In this time, Lueders' bands were used as a visible smart sensor. Generation and propagation of the yielding zone that appeared around circular holes by cyclic loading were clarified. A clear difference was demonstrated between stress concentration factors and experimental values of stress concentration by cyclic loading. It was confirmed that the interference of stress concentration generated in monotonic loading was similar to that of cyclic loading. Comparison of the yielding zone that appeared around circular holes with the stress distribution that was obtained by the FEM analysis, confirmed a difference between monotonic and cyclic loading.