706 応力再配分軌跡(SRL)法による環状切欠き材(S20C)の低サイクル疲労き裂発生寿命推定(OS10-(2) 発電機器の材料・構造解析と評価,オーガナイズドセッション)

概要

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Stress redistribution locus (SRL) method has been proposed to provide an inelastic behavior reasonably employing both the elastic FEM analysis and a unique hyperbolic curve: ε={1/σ+(κ-1)σ}κ, where ε and σ show the dimensionless equivalent strain and stress normalized by the elastic FEM result. After low cycle fatigue tests are conducted using a smooth specimen and four kinds of circumferentially notched bars, the number of cycles to crack initiation got from the experiments is compared with the one estimated by the SRL method. When the adequate elastic region remais inside the notch root, the crack initiation life can be well predicted. However when the plastic region area occupies more than 30% in the notch root section, the equivalent strain range on the notch root surface calculated using the proposed SRL curve and the dynamic stress-strain curve become to be smaller than the one by FEM analyses, and then the crack initiation life will be estimated a bit critically.
2009-08-25