大形疲れ試験の結果について : 第4報, 段付試験片のき裂進行

概要

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The author has studied the relationship between the stress and the propagating speed of fatigue crack by analysing shelly pattern on fracture surface of shoulder fillet specimens obtained by the tests described in Part 3. This analysis was based upon the assumption of the stress σ on the cros section of fillet as follows : [numerical formula] where η : distance from neutral axis for bending C_1,C_2 : constants given by stress concentrating factor. As the results of above studies, it has been presumed that the propagating speed of fatigue crack may be reduced due to coaxing effect and strain harding at the tip of fatigue crack, where the speed is smaller than 0.2μ/c. When the speed exceed 0.2μ/c, it may be obtained from the following formula ; [numerical formula] where υσ_n : stress on edge line of fracture surface kg/mm^2. υ_c : speed of fatigue crack propagation μ/c. σ_o : fatigue strength of specimen having fine crack kg/mm^2. Φ_r : stress gradient on surface layer of cracking part kg/mm^2/mm.
一般社団法人日本機械学会の論文
1961-01-25