Strains and Failure of Pipes Filled with Water and Sealed at Ends as Water Freezes and Expands　(1st Report)

摘要

When a pipe filled with water and sealed at the ends is exposed to a low temperature，it shows progressing strains on the outer wall and failure in the end，due to the low temperature and pacing with the congelation and expansion of the contents. 0ur experiment reports in this paper how the yield condition of the pipe is affected by the size and the treatment of pipes in those atmosphere. A brief result is as follows. 1） It is likely that the pipes not annealed after machining give in the elastic region stress and strain behaviors qualitatively resembling to those when they were under uniform hydrostatic pressure. 2） Yield condition of annealed pipes seems basically to follow the relation : P_y＝2γ_ylnγ， were P_y=internal pressure to give the yield，τ_ｙ=shear strength of the material of the pipe，andγ=ratio of thickness of the pipe. This experiment recommends that τ_ｙ be valued a little less than the shear strength corresponding to the lower yielding point on the tensile test diagram of the actual pipe as a whole