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研究表明冲击对材料表面的层间断裂产生重要影响,但对层间断裂韧性影响的趋势尚不明确。尤其是风机叶片在摆振运动时,叶片所受冲击对叶片表面层间断裂的影响及趋势未见研究。本文首先对风机叶片摆振运动冲击载荷的动力学响应进行研究,确定振型-位移-速度的对应关系,然后对叶片摆振运动过程中的应力-应变-速度进行有限元数值分析,再依据连续介质力学原理建立摆振冲击载荷控制方程,明确摆振运动冲击导致裂缝的应变能释放率(G)和应力强度因子(K)的关系。最后通过对摆振和冲击实验中断裂参数(振型、位移、速度、载荷、起裂方式以及裂纹长度)的测量,验证了本文中摆振运动冲击对Ⅱ型裂缝层间断裂韧性的影响的研究结果,探讨了摆振运动冲击载荷对叶片表面层间断裂韧性影响的趋势。
The research shows that impact has an important influence on the interlaminar fracture on the surface of the material, but the trend of the interlaminar fracture toughness is not clear. In particular, when the fan blades are shimmy, the influence and tendency of the impact of the blade on the interlaminar fracture of the blade surface have not been studied. In this paper, the dynamic response of fan blade shimmy load is studied firstly, the corresponding relationship between mode-displacement and velocity is determined, then the stress-strain-velocity of the blade is analyzed by finite element method The governing equations of the shimmy load are established by the principle of continuum mechanics, and the relationship between the strain energy release rate (G) and the stress intensity factor (K) caused by the shimmy movement is clarified. Finally, the influence of the impact of shimmy motion on the fracture toughness of Type II fracture was verified by measuring the fracture parameters (mode, displacement, velocity, load, mode of initiation and crack length) in the shimmy and impact experiments The results show that the influence of the shock load on the interlaminar fracture toughness of the blade surface is discussed.