回转窑液压挡轮的应力强度与疲劳断裂分析

运用有限元技术对一台大型沥青焦回转窑设备中发生断裂事故的液压挡轮部件进行强度失效分析及疲劳寿命估算.通过断口形貌分析和金相实验,得出失效机理为疲劳断裂的定性结论.利用Ansys软件建立挡轮的有限元模型,计算出应力和变形等一系列结果.在确定交变应力幅值及裂纹尖端应力强度因子的基础上,利用Paris公式预算含缺陷挡轮的疲劳寿命.在选材及造型设计上对挡轮提出改进方案,将韧性较差的铸钢材料替换为韧性较好的锻钢材料,并优化挡轮轮辐减重孔直径,提高挡轮的疲劳寿命,从而在强度及韧性上均达到最优.设计长期交变应力状态下的工件必须兼顾材料的强度、韧性及其造型优化,这一结论对各类动态承载机械零部件的设计均具有参考价值.

STRENGTH AND FATIGUE FRACTURE ANALYSIS OF THE HYDRO-DAMPER OF A ROTARY KILN

The finite element (FE) technique is applied to conducting the strength failure analysis and fatigue life prediction of the hydro-damper used in a large pitch coking rotary kiln. The fatigue fracture conclusion is drawn as the failure mechanism by the analysis of crack locations and appearance and also by the metallographic tests. The FE model of the damper is created and then the stress and deformation distributions are calculated in Ansys. Based on the amplitude of alternating stress and the stress intensity factors on crack tip, the fatigue life of the damper with an initial defect is predicted according to the Paris formula. Modified schemes are presented both on material choosing and structural design. By selecting the ductile forging steel instead of the brittle cast steel, the damper strength and ductility are improved and meet the demands. Comparing the results of equivalent stress distribution in the damper spoke with holes of various diameters, the optimized hole diameter is obtained. Therefore, the material strength, ductility and shape optimization should be considered overall in the design of mechanical components under dynamic loads.