常圧焼結窒化けい素セラミックスの高温引張圧縮繰返し疲労強度に及ぼす応力波形効果

概要

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Push-pull cyclic fatigue tests were performed for silicon nitride ceramics with stress-rate-controlled triangular and trapezoidal stress waves at 1 200℃ at stress ratio R=-1.0. Then the effects of stress rate and stress hold time on the cyclic high-temperature fatigue were examined. The cyclic fatigue life is shorter under trapezoidal stress wave loading than under triangular stress wave loading, and becomes shorter with increasing hold time under the trapezoidal stress wave loading. Cyclic fatigue lifetime is successfully estimated through the crack extension law based on a slow crack growth mechanism, showing a small cyclic stress effect and dominant stress-application-period effect on cyclic fatigue lifetime. This was also evident from scanning electron microscope observations of fracture surface. Cyclic fatigue life was influenced little by stress waves which have hold time on both the tension and compression sides or only on the compression side. Thus compressive stress hold seems not to induce cyclic fatigue damage.
一般社団法人日本機械学会の論文
1996-03-25