完全塑性体の降伏と応力分布(軟鋼有孔板の引張による降伏)

概要

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It has been suggested by Cook, Robertson and Prof. Nakanishi that the yield stress in mild steel is considerably higher when the stress distribution is not uniform as in bending. To explain this phenomenon, Prof. Nakanishi's mean stress theory seems to be more reasonable than Cook's view point of upper yield stress. But, as the yield phenomenon will be considered to be dependent on the type of the stress distribution, the yield condition of a perforated mild steel plate is investigated experimentally in this paper. The results obtained are as follows. In the case of a infinitely small hole, yielding occurs simultaneously over the whole section when the mean stress of the section reaches the lower yield stress, the stress on the periphery of the hole being 3 times of the yield stress ; and in the case of an extremely large hole, yielding begins at the periphery of the hole when the local stress reaches 1.5 times of the yield stress. For the intermediate dimension pf the hole, the neutral yield condition between the above limiting cases is realized, which seems to be governed both by the stress concentration and the mean stress. (Received April 19, 1952)
宇宙航空研究開発機構の論文
1952-06-20