液压挖掘机臂杆结构疲劳寿命预测方法研究

摘要

液压挖掘机臂杆结构承受复杂的冲击载荷,其疲劳寿命存在许多不确定性因素。首先采用Miner 准则,依据实验载荷谱和有限元方法对液压挖掘机工作装置寿命进行了预测。其次研究了结构疲劳寿命变化过程和灰色理论预测模型内在规律的一致性,建立了液压挖掘机工作装置疲劳寿命的灰色预测 GM 模型,并分别运用 GM 模型的两种形式---GM(1,1)线性模型及 GM(1,1)幂模型对液压挖掘机工作装置进行疲劳寿命预测。分析比较 Miner 准则、GM(1,1)线性模型及 GM(1,1)幂模型三种预测方法。结果表明,三种预测方法结果基本一致,灰色系统模型同 Miner 准则模型相比误差明显减小且非线性幂模型具有更高的预测精度。基于灰色理论的 GM(1,1)幂模型考虑了非线性因素,更适合于液压挖掘机工作装置结构疲劳寿命预测。%The fatigue life for arm structure of hydraulic excavator was influenced by many uncer-tain factors because of the complex impact loads were applied to it.Firstly,the Miner’s rule was used, and the fatigue life of work device of hydraulic excavator was predicted based on experimental load spectrum and the finite element method.Then the internal consistency of the changing process of structure fatigue life and the grey theory prediction model was researched,the grey GM model of fa-tigue life prediction of hydraulic excavator’s work device was established,the fatigue life of hydraulic excavator’s arm structure was predicted by using two forms of GM model,the linear model of GM(1, 1)and the power model of GM(1,1 )respectively.Three kinds of prediction methods,the Miner’s rule,the linear model of GM(1,1)and the power model of GM(1,1)were analyzed and compared,it is shown that the predicted results of three methods are basically identical,the error of gray system mod-el is decreased obviously compared with the model of Miner’s rule,and the nonlinear power model has higher predictionprecision.Because the nonlinear factors were considered in gray power model of GM (1,1),the gray power model of GM(1,1)is more suitable for the structure fatigue life prediction of hydraulic excavator’s work device.