液压挖掘机动臂强度分析与疲劳寿命预测

发布时间：2018-03-06 14:40

本文选题：动臂　切入点：静强度　出处：《中南大学》2014年硕士论文　论文类型：学位论文

【摘要】：动臂是液压挖掘机工作装置中重要的构件,实际施工中,动臂既要承受铲斗或者斗杆挖掘时频繁的交变载荷,又要反复进行物料的提升与卸载,且常常受到冲击载荷,受力比较恶劣,容易发生失效事故。本文以山河智能SWE470中型液压挖掘机动臂为研究对象,从静强度及疲劳强度两方面展开研究,并对动臂进行机构优化和结构优化,主要内容如下：建立工作装置面向结构有限元分析的静力学模型,并建立挖掘机整机理论挖掘力和各个关键铰点受力的数学模型,为结构强度分析和结构优化提供依据。建立动臂有限元模型,对位移边界条件进行理论分析和仿真分析,并对典型工况和复合挖掘工况的有限元结果进行对比分析,确定动臂相对薄弱的部位,并找到最危险截面,为动臂的改进提供参考依据。在ADAMS中建立动臂参数化模型,进行铰点优化；在合理的铰点布局基础上,利用APDL建立动臂壳固单元混合的参数化有限元模型,并进行灵敏度分析和结构优化。通过优化降低应力集中,改善应力分布。以SWE470为试验平台,进行应力测试。对动臂进行多工况下的静应力测试,验证有限元模型的正确性。对动臂进行典型挖掘工况下的动应力测试,为后续的疲劳分析提供真实的载荷谱。对应力试验测得的动臂危险点的应力-时间载荷历程进行滤波、雨流计数统计以及编谱处理,得到载荷历程中的各级循环应力。结合动臂材料的S-N疲劳曲线以及静强度分析的有限元结果,应用线性名义应力法理论,通过疲劳分析软件MSC.Fatigue对动臂进行寿命预测,确定疲劳强度薄弱区。
[Abstract]:The arm is an important component of the working device of hydraulic excavator, the actual construction boom, should bear the bucket or the bucket rod when mining frequent alternating load, and repeated material lifting and unloading, and often subjected to impact loads, the stress is relatively poor, prone to failure accidents. This paper takes sunward SWE470 medium arm of hydraulic excavator as the research object, launches the research from two aspects of static strength and fatigue strength, and the movable arm mechanism and structure optimization, the main contents are as follows:
The static model of working device for structural finite element analysis is established, and the mathematical model of excavator's theoretical digging force and the force of each key hinge is established, which provides a basis for structural strength analysis and structural optimization.
A movable arm finite element model is verified by theoretical analysis and Simulation of displacement boundary conditions, and the typical working conditions and mining conditions of the composite finite element results were analyzed to determine the dynamic position of arm is relatively weak, and find the most dangerous section, provide a reference basis for improvement of the boom.
A movable arm parametric model in ADAMS, for optimization of the hinge point; the hinge point layout based on the reasonable use of APDL to establish dynamic arm solid shell model parametric finite element model, and the sensitivity analysis and structure optimization. To reduce the stress concentration through optimization, improve the stress distribution.
The stress test is carried out on the platform of SWE470. The static stress test of the boom under multiple conditions is carried out to verify the correctness of the finite element model. The dynamic stress test of the boom under typical excavation conditions is carried out, providing a real load spectrum for subsequent fatigue analysis.
The dynamic stress time course load filtering of the dangerous point of stress measuring arm test, rain flow counting and spectrum obtained in the course of treatment, the levels of circulating stress. Combined with S-N fatigue curve of arm material and static strength finite element analysis results, the application of linear nominal stress method theory. Through the fatigue analysis software MSC.Fatigue to predict the life of the boom, determine the fatigue strength of the weak area.

【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU621

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