常圧焼結窒化ケイ素の回転曲げ疲労強度

概要

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Rotating bending fatigue tests were carried out to study the cyclic fatigue properties of sintered silicon nitride at room temperature. Thirty-eight specimens were used with the purpose of statistical analysis. The fracture surface was observed using a scanning electron microscope. A large scatter was observed in the fatigue life, but a lower limit S-N curve could be drawn within the range of the present study. Mirror-mist-hackle areas were clearly observed on the fracture surfaces, and it was confirmed that the relation σ・γ^<1/2> = const. holds between the mirror or mist radius γ and the stress amplitude σ. Furthermore, a cyclic slow crack growth region surrounding the fracture origin was observed on some of the fracture surfaces. Finally, supposing the slow crack growth under cyclic loading, the scatter of fatigue lives was explained as a first approximation from the scatter of defect sizes inherent to the material.
一般社団法人日本機械学会の論文
1987-08-25