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本文用断裂力学方法对压气机和风扇转子叶片作损伤容限分析。采用 2 0节点立体元对叶片作应力场和位移场计算 ,用裂纹表面位移法求解裂尖应力强度因子 K 、K 及 K 随裂纹长度a变化的关系。根据叶片材料的断裂韧性 KIC、叶片径向伸长量δc 以及自振频率偏移量 fc 值来确定转子叶片失效的准则及临界裂纹长度 ac值。利用 Paris公式并考虑到高周振动应力对低周疲劳裂纹扩展的影响求得叶片的损伤容限寿命 Nf。文中给出了某压气机叶片的算例。为了研究自振频率随裂纹长度变化的关系 ,进行了叶片振动实验
In this paper, the fracture mechanics method is used to analyze the damage tolerance of compressor and fan rotor blades. The stress field and displacement field of the blade were calculated by the solid element of 20 nodes, and the relationship between the stress intensity factors K, K and K at crack tip was solved by the crack surface displacement method. According to the fracture toughness of the blade material KIC, the blade radial elongation δc and natural frequency fc value to determine the failure of the rotor blade failure criteria and critical crack length ac value. The damage tolerance life (Nf) of the blade was obtained by using the Paris formula and considering the effect of high-frequency vibration stress on the propagation of low-cycle fatigue cracks. An example of a compressor blade is given in this paper. In order to study the relationship between the natural frequency and the change of crack length, the leaf vibration experiment was carried out