In this paper, the result from rotating bending fatigue tests of notched specimens are carried out on aluminum cast alloys and high strength steels with HB≃600 are reported. The threshold stress intensity factor range under a stress controlled condition, ΔKw, is introduced for the purpose of predicting the fatigue limit of a metal with an arbitrary crack. The ΔKw, value of a long crack, ΔKwUL is obtained from the fatigue crack propagation limit σw2 of specimens with a sharp and deep notch: ΔKw increases with crack length, and ΔKwUL is an upper limit of ΔKw. Since there are few σw2 data of steels with HB≥400, the σw2 values are evaluated by the fatigue crack initiation limit predicted using Linear Notch Mechanics and the relation between σw1 and σw2 at the branch point. Using ΔKwUL values of many metals with a long crack, the ΔKwUL values are approximated with a simple formula. Moreover the lower limit value of ΔKw versus the crack length, ΔKwLL, is proposed. Then using the ΔKw and ΔKwUL formulae and the ΔKwLL value, the smallness of a fatigue crack is clarified.
|Number of pages||8|
|Journal||Nippon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A|
|Publication status||Published - Sept 2002|
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering