鋼の疲労破壊予知に関する基礎研究

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The reslt of our investigation whether it is possible or not to anticipate the crack initiation and cr- ack growth behaviour by utilizing the direct current electrical potential method is reported. The e1ectri-cal resistance in steel specimens subjected to repeated bending stress was measured from the fatiguecrack initiation and crack growth to the fatigue fracture.The main results obtained are as follows:ll) The electrical resistance in steel specimens changed according to the increase of the cyclic number at the bending fatigue tests.(2) The initiation electrical resistance in steel specimens increased to the 3% fatigue life at the bend-ing fatigue tests. Afterwards. the electrical resistance in steel specimens decreased to the 10% fatigue life.(3) It is confirmed by continuously microscopic observation that fatigue initiation crack exists in 3%fatigue life.(4) The electrical resistance in the bending fatigue tests is of the occurreence of an initial stage (initi-al formed of fatigue cracks). a middle stage (gradual crack growth) and a latter stage (acceleratedcrack growth).Thus. the availability of using the direct current electrical potential for anticipating the crack initi ation and crack growth behaviour is verified by experiments using Low-Carbon Steels.Key Words : direct current electrical potential method. anticipating of crack initiation and crackgrowth behaviour. electrical resistance
福島工業高等専門学校の論文