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Fatigue life prediction and reliability analysis of the forage crusher rotor
Haixu Zhao,Zhiping Zhai,Yingsheng Mou,Le Liu,Yuezheng Lan,Hongmei Cui 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4
To accurately predict fatigue life and reliability of the forage crusher rotor, the stress load spectrum of the rotor is obtained via the two-way fluid-structure coupling method, which calculates the coupled flow field in the forage crusher and rotor structure. The fatigue life of the rotor is predicted, and its reliability is analyzed. Finally, the rotor is optimized by a multiisland genetic algorithm. The results indicate that the fatigue life prediction based on fracture mechanics theory and the Gerber average stress correction method is more suitable for the prediction of the rotor’s fatigue life. After optimization, the fatigue life cycles of the rotor are increased from 1.229×10 8 to 7.67×10 8 and the reliability is increased from 89.4 % to 99.7 %. This meets the reliability requirement of key parts of agricultural and animal husbandry machinery. This study provides a reference for the prediction and optimization of fatigue life and reliability of forage crushers.
Zhifang Zhao,Yang Yang,Hui Ma,Haixu Wang,Hongxu Tian,Chenyi Han 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1
Assembly errors may change contact state of gear pairs, then induce failure and vibration. To reveal the effects of assembly errors and tooth modification on the meshing characteristics, the loaded tooth contact analysis (LTCA) is conducted through an improved algorithm. The time-varying meshing stiffness (TVMS), static transmission error (STE) and contact stress (CS) are calculated considering assembly errors and tooth modification. Then, sensitivity of meshing characteristics to coupling assembly errors are investigated based on the design of orthogonal experiment (DOE). The meshing characteristic analysis results show that assembly errors have a significant effect on mesh characteristics of the gear pair. The results of sensitivity analysis indicate that the meshing characteristic is the most sensitive to axial deviation for the model used in this paper.
Zhiping Zhai,Donghai Yuan,Yuezheng Lan,Haixu Zhao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10
During the operation of a forage crusher, the common issues usually faced are shorter mean time between failures and low reliability. The hammer rotor, a critical component, is prone to fatigue fracture, hammer wear, violent vibration of the rotor system caused by uneven wear of the hammers, and other issues that reduce the machine's service life and reliability. In order to avoid failure modes within the design life of the forage crusher and improve its reliability, the functional functions of the fatigue fracture failure, hammer wear failure, and resonance failure modes were established, the marginal distribution functions for each individual failure mode were computed, and the reliability model of the hammer rotor under multiple failure modes is constructed based on the correlation degree between the failure modes. On this basis, the reliability of the forage crusher is improved by optimizing the structure and working parameters. Before optimization, the fatigue reliability, wear reliability, and vibration reliability of the hammer rotor are 0.878, 0.94, and 0.248, respectively, and the reliability of the hammer rotor under multiple failure modes is 0.2116. After optimization, the fatigue, wear, and vibration reliability are 0.979, 0.9997, and 0.932, respectively. The reliability of the hammer rotor under multiple failure modes is 0.923, which reduces the probability of failure within the design life and meets the requirement that the reliability of key parts of agricultural and animal husbandry machinery is not less than 90 %. This study validates the reliability models and multi-objective optimization results and serves as a reference for forage crusher structural reliability design and optimization.