Kenji Yoshii

Estimation of Fatigue Strength of Fabricated Component

This paper deals with the fatigue performance of fabricated component. The plain fatigue and fatigue crack growth tests were performed. The rectangular bar specimens sectioned from the fabricated components after rolling, forming and cold spinning processes were prepared. Four-point bend fatigue tests of the specimens with as-fabricated surfaces were carried out at a stress ratio of 0.1 and a frequency of 20 Hz with a sinusoidal waveform. The crack growth behavior of specimens at various stages of fabricating process was also investigated. The fatigue test results indicated that surface morphology and surface defect induced by each stage of fabricating process strongly degraded the fatigue strength. The limited influence of fabricating process on crack growth behavior was noticed only in the threshold region. Fatigue strength and fatigue life were estimated based on fracture mechanics approach using the fatigue crack growth curve obtained and the surface defect depth observed on the fabricated surface. The estimated fatigue strength and the experimental results were in good agreement.Copyright