基础激励下裂纹梁结构疲劳寿命预测模型

Fatigue Life Predication Model for a Cracked Beam Structure Under Base Excitations

为了发展基于模型的裂纹梁结构疲劳寿命预测方法,提出了一种新的三维裂纹梁单元刚度矩阵。基于该刚度矩阵,建立基础激励下裂纹梁结构的三维有限元模型。推导三维裂纹梁单元的应力强度因子,建立三维裂纹梁单元的疲劳裂纹扩展模型。采用振动响应与裂纹扩展增量交互计算方法,计算循环载荷作用下裂纹梁结构的疲劳寿命。研究结果表明:裂纹梁结构寿命预测模型较好地体现了疲劳裂纹扩展寿命与基础激励参数、结构参数和裂纹参数之间的内在关系,反映了基础激励对裂纹梁结构疲劳寿命的影响。最后通过实验对模型进行了验证。

For the purpose of developing a reliable model-based approach,a new stiffness matrix of a three-dimensional(3D)fi⁃nite element is proposed for modelling a cracked beam structure.Using the obtained stiffness matrix,the 3D finite element model of the cracked beam structure was established.The equation of stress intensity factor for the 3D beam element with a crack was formed,and the fatigue crack growth model for the 3D beam element with a crack was established.The dynamic response and crack growth increment was calculated interactively,and lasts from the initial crack length to final crack length cycle by cycle.The study shows that fatigue life prediction model discovers the internal relation between the fatigue crack growth and base excita⁃tion parameters,structural parameters and crack parameters,and that the effect of base excitation on fatigue crack growth of the cracked beam structure was determined and discussed.Finally,an experiment was conducted to validate the analytical results.