構造用鋼の超低サイクル疲労破壊に関するエネルギー的考察 : 累積損傷エネルギーと大予ひずみの効果

概要

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From the results of monotonous tensile fracture test of cylindrical specimen and hourglass specimen(SR295), it becomes clear that the volume change occures in the plastic domain. From the experimental result on the extremely low cycle fatigue fracture of the cylindrical specimen (SR295 and SS400, G.L.=2.5D=28.25mm), taking large plastic amplitude into consideration, it becomes clear that the hysteresis loop loses its symmetricity. The cumulative damage energy hypothesis by Coffin et al. may be applicable for extremely low cycle fatigue of structural steel. In order to make clear the effect of damage energy on extremely low cycle fracture of C+TF test (the tensile fracture test after the initial compressive loading) and T+C+TF test (the tensile fracture test after the initial tensile and compressive loading) are carried out. From the results of the test, it becomes clear that the larger the first amplitude of strain, the larger the maximum resistance. Fracture strains are influenced by the strain amplitude of the first passage, i.e. beyond 22.5% on C+TF test and beyond 20% on T+C+TF tests. The cumulated damage energy, which dissipated at the last tensile fracture is almost the same as the cumulated damage energy under monotonous tensile fracture test.
社団法人日本建築学会の論文
2000-08-30