On the Endurance Limits and Their Reliability of Larger Castings and Forgings : Statistic Investigation on the Fatigue Strength of Cast and Forged Crank Throw

概要

論文の詳細を見る
Endurance limits and their reliability of larger casting and forgings are statistically discussed on the rotating beam fatigue test results using laboratory-sized specimens obtained from two B&W 98 type crank throws (pin diameter: 868mm, weight: 20 ton, tensile strength: 56 kg/mm^2) of which the one is die forged steel and the other is ordinary cast steel. 1) Fatigue life variance of the casting, which is explained in coefficient of variation (standard deviation of fatigue life/mean fatigue life) is about 10% larger than that of the forging. 2) Mean values of endurance limit and standard deviation of the casting, which is determined with staircase method are respectively 22.1 kg/mm^2 and 2.87 kg/mm^2, while those of the forging are 28.3 kg/mm^2 and 1.17 kg/mm^2/ Therefore, it should be noted that confidence limit of endurance limit (mean value-standard deviation ×2) of the casting is 16.4 kg/mm^2, while that of the forging is 26.0 kg/mm^2; also(mean value-standard deviation ×3) of the casting is 13.5 kg/mm^2, and that of the forging is 24.8 kg/mm^2.
一般社団法人日本機械学会の論文