間欠ひずみ波形に対する疲労寿命予測

Abstract

Fatigue tests have been made on a SUS 316 stainless steel at 550°C under stress patterns of intermittent strain wave form which is composed of cycling of a large pulsating strain and superposed small strain cycling. A rest time was 5sec. and it was introduced at zero strain of a large strain cycle.The method of life prediction for the strain cycling was examined on the basis of a linear cumulative damage concept. A linear rule based on the fatigue life curve under a constant strain amplitude gave a reasonable prediction in the case that the superposed small strain was a larger fraction of the basic large pulsating strain, although it gave a poor prediction in the case that the superposed small strain was a small fraction of the latter.By using Manson's 10per cent rule, a reasonable life was predicted regardless the fraction of the superposed small strain to the basic large pulsating strain.