Relationship between strain and central deflection in small punch creep specimens

摘要

Acquiring information about creep strain directly from small punch creep tests is difficult because the deformation behaviour of the small punch specimen is complicated. A routine is suggested in the present paper to treat this problem indirectly. Based on a finite element analysis, it is proposed that the relationship of central deflection delta to central creep strain epsilon _c of a specimen subjected to creep can be represented approximately by the relationship of central deflection delta to central (elastic-plastic) strain epsilon of a specimen not subjected to creep. With this hypothesis, the delta approx epsilon _c relation of the small punch creep specimen is obtained by resorting to a rigid-plastic membrane stretch forming model. Finally, small punch creep test results are used to evaluate creep strain and creep strain rate by taking advantage of this delta approx epsilon _c relation.