定応力クリープおよぴ定荷重クリープ曲線から得られるθ投影法パラメータの関係

抄録

The θ projection concept, recently developed to predict not only creep curves even in tertiary creep but also long-term creep properties, required constant-stress creep data. The authors designed a constant-stress creep machine, only changing the conventional loading lever of the constrant load creep machine into the profiled cam lever. The purpose of this study is to examine whether there is relationship of parameters between constant-stress and constant load creep curves derived from the θ projection concept. Both creep tests were conducted using duralumin at 250°C. Six kinds of cutoff strains were proposed to systematically obtain four parameters, e. g., values of standard error or dimensionless standard error. The creep curves can be described precisely within the standard error of 0.02%. However, poor relationships of parameters between both creep tests were recognized because creep strain at rupture was small in the test material.