Integrated evaluation of the stress-strain state of metal structures of the working equipment of a mining excavator

Operating experience and analysis of documents of the maintenance and repair service of the Mining Administration shows that most often cracks in EKG-20 excavators are formed in the metal structures of working equipment, and that it is important that cracks often occur in the base metal, especially for the excavator boom. Due to the formation and growth of cracks, the service life of this basic excavator assembly is significantly reduced, which in theory should have the necessary safety margin to ensure the required level of machine reliability. In the total share of failures of excavators due to failure of supporting metal structures, defects in the metal structures of working equipment account for up to 70%. To establish the real reasons for the formation of cracks on the metal structures of the working equipment of the EKG-20 excavators, an assessment was made of indicators characterizing the actual loading of the metal structures of the working equipment in real operating conditions. The actual technical condition of the working equipment units was assessed on the basis of parameters that allow taking into account such important components as: fatigue, residual stresses and deformations, changes in the metal microstructure that the equipment acquired during operation under cyclic loading conditions. Stress concentration zones are identified and their boundaries are determined. The deformations are determined and the stresses arising under the action of working loads in various operating modes in the areas of stress concentration, metal structures of the handle and boom of the excavator are calculated. Based on the calculation results, a selection of the maximum tensile and compressive stresses that occur in the established stress concentration zones was made. The assessment of the identified stress concentration zones as sources of fatigue damage initiation was carried out.

Nabiullin R. Sh. Integrated evaluation of the stress-strain state of metal structures of the working equipment of a mining excavator. MIAB. Mining Inf. Anal. Bull. 2023;(12−1):93—105. [In Russ]. DOI: 10.25018/0236_1493_2023_121_0_93.

Nabiullin R. Sh., Cand. Sci. (Eng.), assistant professor, department of mining machines and complexes, «Ural State Mining University», Ekaterinburg city, e-mail: nabiullin.r@m. ursmu.ru, ORCID ID: 0000-0001-7519-2156.

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