任意応力場における疲労き裂伝播シミュレーション : RPG規準による疲労き裂伝播挙動の研究(第2報)

概要

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A fatigue crack propagation model in an arbitrary stress distribution field is developed considering the crack opening and closing phenomena, based upon the Dugdale model where the displacement continuity is satisfied by continuously plugging in segments for the fictitious crack surface displacement in the plastic zone. The present model is further modified as to leave the plastically deformed materials along the crack route as such, as the crack advances. In the model, reciprocal theory for cracked body is adapted for the purpose of obtaining the elastic COD under an arbitrary stress distribution, which shows good agreement with calculated COD by FEM or BEM. Fatigue crack propagation test for a CT specimen with a circular notch is carried out for the purpose of measuring the crack opening/closing load and the Re-tensile Plastic zone Generated load as a function of crack length. It becomes obvious that the crack opening load is less than the crack closing load. The calculation results of crack opening load and Re-tensile Plastic zone Generated load by the developed simulation program are shown to be in good agreement with experimental ones, if the cyclic yield stress is adopted as the yield stress, except immediately after crack initiation. It is considered that this difference may be the result of not considering the yield phenomenon near the notch root.
社団法人日本船舶海洋工学会の論文
1992-03-29