ローラ加工による切欠材の疲労強度向上

概要

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According to the classification of the failures cause, as more than 90% failures are caused by fatigue and more than 90% of fatigue cracks initiated from the stress concentrated parts of a structural component, it is practically important to investigate the improvement of fatigue strength of notched parts. However, there are few reports on the improvement of fatigue strength about notched specimen based on the viewpoints of fatigue mechanism and the theoretical analysis. Though a hard-facing method is pretty effective for plain specimen to increase the fatigue strength, but not for notched specimen. Then, the authors have considered that the plastic deformation by roller working is one of the best method to improve the fatigue strength of notched specimen. The main results obtained in this test are as follows ; (1) The fatigue limit of notched specimen with roller working increases by 220% than that of without roller working. (2) The increase of the above fatigue limit would be attributed to work-hardening & strain-again due to plastic deformation and compressive residual stress at the surface layer of notched bottom. (3) The non-propagating micro cracks in the depth of 0.4 mm at the notched bottom are observed in the specimen suffered by 1×10^7 cycles under the stress amplitude of fatigue limit, which has the notched radius as long as 2 mm.
一般社団法人日本機械学会の論文
1998-12-25