据込加工の挫屈に対する限界高さ-直径比

概要

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An experimental and theoretical study on the critical height-diameter ratio (l_0/d_0)_<cr>, with which cylindrical bar can be upset without buckling is reported in this paper. For the theoretical analysis, the theory by Engesser-Karman is applied taking into account of large compressive strain before buckling but the irregular end conditions. This analysis is made simplified by the use of n power law for the true stress-logarithmic strain relation of the material tested. The theoretical (l_0/d_0)_<cr> value ranges between 2.95 for annealed 65/35 brass and 1.81 for duralumin, under the condition that both ends of bar are allowed to move freely in the transverse direction (equivalent to 'both ends supported'). The experimental value under corresponding condition is 2.7 for brass and 1.4 for duralumin respectively, and is a little lower than the former for each material, probably on account of eccentric loading. It is to be noted that (l_0/d_0)_<cr> value increases with n. When the test bar is upset under dry friction state on its end surfaces (nearly equivalent to 'both ends fixed'), the buckling of higher order occurs. The (l_0/d_0)_<cr> value in this case, is about 1.4 times (2 times theoretically) of the theoretical value for both end supported condition. This would be due to non-uniform deformation of the test bar caused by end constraint.
宇宙航空研究開発機構の論文
1954-07-30