考虑小裂纹特性的裂纹扩展数值分析方法及实验验证

Numerical Analysis Method and Experimental Verification of Crack Propagation Considering Small Crack Character

关键词:  镍基粉末高温合金  小裂纹  缺陷  裂纹扩展  数值方法

Key words:  Nickel-based superalloy  Small crack  Defect  Crack growth  Numerical method

摘要:

为了对工程断裂关键件进行全面的损伤容限分析，需要发展一种能够考虑小裂纹阶段的疲劳裂纹扩展数值分析方法。在Paris公式的基础上基于镍基粉末高温合金小裂纹扩展行为特点，提出了一种小裂纹加长裂纹阶段的裂纹扩展物理力学过程描述，并以此建立了裂纹扩展速率模型。同时考虑到工程应用，将该模型通过Franc 3D软件的用户子程序，与有限元方法结合，构建了一种可分析实际工程结构例如航空发动机涡轮盘上疲劳裂纹扩展的数值分析方法。针对带初始缺陷的FGH96合金标准试棒进行了裂纹扩展数值分析，并与开展的裂纹扩展寿命实验进行了对比。数值计算结果与实验结果吻合较好，表明该方法能够充分考虑小裂纹阶段的裂纹扩展行为特点，适用于分析工程结构疲劳裂纹扩展的全过程。

Abstract:

In order to conduct a comprehensive damage tolerance analysis of critical engineering components， it is particularly important to develop a numerical analysis method for fatigue crack growth that can consider the small crack stage. Accounting for the characteristics of the small crack growth behaviour of nickel-based powder superalloys， a crack growth rate model applicable to both small crack and long crack based on the Paris formula was proposed. At the same time， considering the engineering application， this model was inserted into the Franc 3D software through the python extensions to construct a numerical analysis method that could analyse the fatigue crack growth of the actual engineering structure such as the aero-engine turbine disk. Numerical analysis of crack growth was carried out on the FGH96 alloy specimen with initial defects. The numerical calculation results are in good agreement with the experimental results， indicating that the method can sufficiently consider the characteristics of crack growth behaviour at the small crack stage， and is suitable for analysing the whole process of fatigue crack growth in engineering structures.