Stress concentration and fatigue strength of notched specimens under repeated bending moment (5th report) : circular shaft with a diametral hole no.2

外周切欠材の応力集中と回転曲げ疲労強度について : 第5報 孔付円筒軸 その2

Stress concentration and fatigue strength of notched specimens under repeated bending moment (5th report) : circular shaft with a diametral hole no.2

Creators Ono Motoaki

The relation between the form factor α and the notch factor β in various notched parts has been researched and discussed by many investigaters. In our country, T. Ishibashi discussed these problems especially in the circular shaft with a diametrical circular hole under bending action and proposed two kinds of emperical formulas of which the first based upon the yielding stress and the second upon the fatigue limit of the plain specimen of the material itself. His formulas are made up of the relative maximum stress gradient at the root of the notch and a small distance ε_o and ε'_o from the notch root to the direction of the maximum stress gradient on the munimum cross section. However in the relation between α and β there should be much more factors : the material strength, part size, stress gradient, relative grain size etc. Then it is desired to devise more profound formula. By an assumption of the criterion limitting the mean stress on a small range measured from the root of the notch to the direction above mensioned necessry tor a crack arising and propagation, I devised an emperical formula of the form β=α〔1-k・(d, d/D, ψ, ε_o)〕 where k=const, d=dia. of the hole, D=dia. of the shaft, ψ=relative stress gradient, ε_o=small distance. This formula is reduced to a simplified formula in the caluculation of approximate values of β under repeating bending stress or tension compression stress, and has a good fit between calculated values and experimental results.

[ISSN]0372-7661

[NCID]AN00244228