硬質ポリ塩化ビニルの疲労き裂進展と破面形態

概要

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The fatigue crack propagation behavior and the fracture surface appearance under several load conditions in polyvinyl chloride were investigated. The crack closure behavior was also examined. The fatigue crack propagation rate, da/dN, under constant amplitude loading increased with increasing stress ratio in the relationship of da/dN versus the stress intensity factor range, ΔK. This effect of stress ratio on da/dN was closely related to the crack closure behavior when the stress ratio was not so high. Discontinuous growth bands(D.G.B.)on the fracture surface seemed to be difficult to be formed when the stress ratio was very high. The width of D.G.B.was found to be dominated by the effective stress intensity factor range, ΔK_<eff>. The crack extension during loading a single peak overload was very large and so it could be clearly identified on the fracture surface. This region of the crack extension on the fracture surface revealed granular markings containing many voids, which was similar to that found in D.G.B.. The amount of this crack extension was about equal to the size of the plastic zone at the crack tip formed by the overload under a plane strain condition.
社団法人日本材料学会の論文
2000-05-15