冲击疲劳裂纹扩展(英文)

Impact fatigue crack propagation

本文综合归纳了金属材料的冲击疲劳裂纹扩展研究。讨论了冲击应力特征参量 ,如应力幅值 ,加载时间 ,2次应力峰值和过载 ,对冲击疲劳裂纹扩展速率的影响 ;对材料在冲击和非冲击疲劳载荷作用下的裂纹扩展行为进行了比较。结果表明 :冲击应力特征参量对冲击疲劳裂纹扩展速率的影响规律与其裂纹尖端的微观变形、断裂机制有关 ;材料在冲击和非冲击疲劳载荷作用下的裂纹扩展速率存在 3种不同的关系 ,并取决于材料在冲击和非冲击疲劳载何作用下的裂纹扩展机理 ;应力幅值 ,应力花样和材料的显微组织对材料的冲击疲劳裂纹扩展的影响大于对非冲击疲劳裂纹扩展的影响 ,冲击载荷常导致材料脆化并加速材料的疲劳裂纹扩展。

In this paper,the impact fatigue crack propagation behaviour of metallic materials is summarized.The effects of impact stress pattern characteristic parameters, such as stress range,loading time,secondary stress peaks and overload on impact fatigue crack growth rates are discussed.The comparison of crack propagation behaviour between impact and nonimpact fatigue is described.It demonstrates that the effect regularities of impact stress pattern characteristic parameters on impact fatigue crack growth rates are related with the mechanism of material deformation and fracture at fatigue crack tip.There are three different types of relations in the crack growth rates in impact and nonimpact fatigue.These relations are strongly associated with the microfracture mechanisms under impact and nonimpact fatigue loads.The effects of stress ranges,stress patterns and microstructures of materials on crack growth are larger in impact than in nonimpact fatigue loadings.Impact loading usually induces materials embrittlement and accelerates the fatigue crack growth behaviour.