変動引張荷重を受ける鋼のフレッチング損傷と疲労

概要

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Fretting fatigue tests were carried out using a device designed specially with respect to the fretting fatigue of crank pin bolts used in marine diesel engines. A 0.46%carbon steel was tested in fluctuating tension at a frequency of 30 Hz and a clamping load of 392 N in air. The effect of fretting on the fatigue performance was investigated. The effectiveness of the electrodeposited coatings and of the insertion of a thin metallic sheet were assessed for the mitigation of the fretting fatigue failure. Fretting had a serious damaging effect on the fatigue performance, reducing the fatigue life at stresses well below the normal fatigue limit. The ellectrodeposited coatings of copper, silver, and zinc were beneficial. They showed sufficient ductility to withstand the streses without cracking and also to remain in the contact area without being extruded. However nickel and chromium coatings and seemed to penetrate into the underlying steel. Double layered coatings such as chromiun on copper on the substrate were remarkably effective in improving the fatigue life.
社団法人日本マリンエンジニアリング学会の論文