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为了模拟功能梯度材料(FGM)在工程应用中可能会出现的断裂问题并计算相应的开裂载荷,通过编写用户自定义UEL子程序将梯度扩展单元嵌入到ABAQUS软件中模拟功能梯度材料的物理场,并编写交互能量积分后处理子程序计算裂纹尖端的混合模式应力强度因子(SIF),采用最大周向应力准则编写子程序计算裂纹的偏转角,并模拟了裂纹扩展路径,计算了裂纹的起裂载荷。讨论了材料梯度参数对裂纹扩展路径以及起裂载荷的影响规律。通过与均匀材料的对比,验证了功能梯度材料断裂性能的优越性。研究表明:外载平行于梯度方向时,垂直梯度方向的初始裂纹朝着等效弹性模量小的方向扩展,且偏转角在梯度指数线性时出现峰值,并随着组分弹性模量比的增加而变大;当外载和初始裂纹均平行于梯度方向时,材料等效弹性模量和断裂韧性的增加或者梯度指数的减小都导致起裂载荷变大。
In order to simulate the fracture problem that FGM may have in engineering application and calculate the corresponding cracking load, the gradient expansion unit is embedded into ABAQUS software to simulate the physical field of FGM by writing a user-defined UEL subroutine. Then the subroutine of interaction energy integral post-processing was used to calculate the mixed mode stress intensity factor (SIF) of the crack tip. The maximum circumferential stress criterion was used to write a subroutine to calculate the deflection angle of the crack, and the crack propagation path was simulated. Load. The influence of material gradient parameters on crack propagation path and initiation load is discussed. By comparing with uniform materials, the superiority of fracture property of functionally graded material is verified. The results show that when the external load is parallel to the gradient direction, the initial crack in the vertical gradient propagates in the direction of small equivalent elastic modulus, and the deflection angle peaks exponentially with gradient index. With the elastic modulus ratio Increases and increases. When both the external load and the initial crack are parallel to the gradient direction, the increase of the equivalent elastic modulus and the fracture toughness or the decrease of the gradient index lead to the increase of the initiation load.