摘要：循環載荷下受廣大彈性區包圍的I型裂紋尖端塑性區的材料疲勞破壞本質上屬于應變疲勞，若考慮I型裂紋尖端在局部應變循環下會以突進方擴展，則可假定每次突進擴展量是平均損傷或應變能達到臨界狀態時裂尖塑性區的斷裂擴展。基于這個思想，考慮I型裂紋裂紋尖端塑性累積損傷與應變能準則并依據I型裂紋尖端區循環應力應變場有限元解及I型裂紋裂尖區HRR（Hutchinson-Rice-Rosengren）單調應力應變場和RKE（Rice-Kujawski-Ellyin）循環應力應變場場，發展了一套基于RVE（材料代表性單元）低周疲勞臨界損傷律實現對平面應力I型疲勞裂紋擴展規律的有限元分析方法和理論模型。應用新建立的兩類理論模型結合15種金屬材料，對疲勞裂紋擴展規律進行了預測，結果表明新模型具有廣泛普適性。成果可用于含裂紋結構的結構完整性分析。
　　關鍵詞：低周疲勞，疲勞裂紋擴展，塑性損傷，塑性應變能，斷裂，裂紋，工程材料

　　Abstract:Material fatigue failure within the plastic zone near crack tip for mode-I crack essentially belongs to strain fatigue, under cyclic loading due to existing large elastic constraint.  As it is assumed that the mode-I crack propagates in step-type under local strain cycling, the step-type propagation magnitude of the crack at a time is equal to the dimension of plastic zone when the average damage or strain energy of the zone reaches the critical state. Therefore,based on above thoughts and according to some mechanics aspects such as the plastic accumulation damage, the plastic strain energy for mode-I crack tip and the cycle stress or strain solution from the finite element fields, and the Hucthinson-Rice-Rosengren （HRR） or the Rice-Kujawski-Ellyin （RKE） stress-strain fields, the several new methods by finite element and theoretical models are developed to establish the relations between the low cycle fatigue properties and the mode-I crack propagation rate of materials. Finally, fatigue crack growth laws are investigated by the new models developed and the experimental data of fifteen kinds of engineering materials. The results show that the proposed theoretical models and finite element method can be widely used to describe the behavior of material fatigue crack propagation for mode-I crack. The new theoretical models can be applied in the structure integrity estimation including surface crack.
　　Key words : Low cycle fatigue,fatigue crack growth,accumulation damage,strain energy, fracture, crack, engineering material
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