クリープと高温低サイクル疲労の損傷則(<小特集>高温強度小特集)

概要

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This paper proposes a common damage rule of creep and low cycle fatigue at elevated temperatures on the basis of the idea that the accumulating rate of damage is proportional to the rate of plastic deformation at the local position where cracks initiate and propagate. Applications of the damage rule to the problems of creep rupture, tensile rupture, low cycle fatigue at elevated temperatures and low cycle fatigue with hold time, lead to the failure laws, some of which have already been proved to be valid by experiments, such as stress-time to rupture and minimum creep rate-time to rupture relations in creep, and frequency modified fatigue law in low cycle fatigue. The failure laws explain not only the features of failure behavior under each loading condition, but also the relationships among them. The authors tried to estimate the low cycle fatigue life from the creep data, and found that the estimated lives agree fairly well with experimental lives. It is concluded that the break in slope of log minimum creep rate-log time to rupture curves in creep, that of log plastic strain range-log number of cycles to failure curves and frequency dependency in low cycle fatigue arise from the difference between the rate controlling process of macroscopic deformation of a specimen and that of local microscopic deformation at an actual fracture region.
社団法人日本材料学会の論文
1974-03-15