Journal of South China University of Technology(Natural Science) >

2022 , Vol. 50 >Issue 8: 62 - 70

DOI: https://doi.org/10.12141/j.issn.1000-565X.210689

Mechanical Engineering

Fatigue Life Evaluation of Excavator Working Device Based on Equivalent Structural Stress Method

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  • Key Laboratory of Road Construction Technology and Equipment of the Ministry of Education，Chang’an University，Xi’an 710064，Shaanxi，China
曹蕾蕾（1983-），女，博士，副教授，主要从事工程机械动态仿真与抗疲劳设计研究。

Received date: 2021-11-01

  Online published: 2022-01-11

Supported by

the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(2015BAF07B02)

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Abstract

The working device of the excavator is a large welded structure, which is prone to damage at the weld due to various complex loads during the operation, and its fatigue strength is directly related to the service life and performance of the whole machine. In order to evaluate the fatigue life of its welds more effectively, an evaluation method of weld fatigue life of excavator working device was proposed based on the equivalent stress method in this paper. That is, based on the node force and node moment on the welding line, the structural stress that is not sensitive to the grid is calculated. The fatigue life is evaluated by the fatigue cumulative damage criterion and the main S-N curve of welded joints, which can unify with different joint types, plate thicknesses, and loading modes. By building the finite element models with detail information of the welding seam for the boom and bucket, the fatigue damage assessment was carried out for six key welds on the boom and the bucket by the equivalent structural stress method. The fatigue assessment accuracy of the boom and the bucket is comparatively studied with the fatigue experiment results in this study, the results indicate that the deviations obtained through the nominal stress method are 9.2% and 14.2%, and they reach to 24.4% and 23.4% by employing the hot spot stress method and decrease to 6.6% and 9.5% in the approach with equivalent structural stress analysis. Therefore, compared with the nominal stress method and the hot spot stress method, the evaluation results of the equivalent structural stress method are the closest to the fatigue test results. The evaluation results of the nominal stress method tend to be bold, while the evaluation results of the hot spot stress method tend to be conservative, which means that the equivalent structural stress method is very effective and reliable for the fatigue life assessment of excavator working device. The proposed method can provide ideas for the fatigue life assessment of other welded structures.

Key words： excavator; working device; equivalent structural stress method; welding structure; fatigue life evaluation

Cite this article

CAO Leilei, WANG Liutao, WANG Yan, et al . Fatigue Life Evaluation of Excavator Working Device Based on Equivalent Structural Stress Method[J]. Journal of South China University of Technology(Natural Science), 2022 , 50(8) : 62 -70 . DOI: 10.12141/j.issn.1000-565X.210689

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