基于铸造缺陷信息叠加算法的有限元疲劳分析

Fatigue Analysis of Casting Based on the Defect Superposition Algorithm and Finite Element Method

铸件中铸造缺陷破坏材料的连续性,易引起材料局部应力集中和易为疲劳裂纹扩展源。但由于铸造缺陷特征的表征十分复杂,使得目前无法构建含缺陷的力学模型。针对装载机摇臂铸件,采用了有限元网格模型传递及缺陷信息叠加算法,建立了包含铸造缺陷信息的非均质网格模型,在此基础上进行了无缺陷摇臂铸件与含铸造缺陷的摇臂铸件的结构及疲劳对比分析。结果表明:铸造缺陷会在铸件内形成局部应力集中,在相同的加载条件下时,含缺陷的摇臂铸件的应力集中度比无缺陷的摇臂铸件大,且铸造缺陷周围会出现明显的低疲劳寿命区域;在采用脉冲载荷历程情况下,铸件中的缺陷使得该部件疲劳寿命降低1/3以上。

Porosity breaks continuity of casting, stress concentration and fatigue crack propagation source are easy to occur in these positions. However representation of casting defect features is very constructive, which can＇t construct the mechanical model containing defects. Aiming at the loader, the heterogeneity grid model with casting defects has established based on the finite element mesh transmission with defects information superposition algorithm, then structure and fatigue comparative analysis of the rocker casting with and without defects has been conducted. The present results indicate that defects can form local stress concentration under the same loading conditions. And also the low fatigue life will appear in the around casting defects, the casting defect has reduced the fatigue life of the rocker casting by one third.