Load characteristics analysis of tractor drivetrain under field plowing operation considering tire-soil interaction

The drivetrain of a tractor is prone to fatigue failure under heavy load plowing operations. The load variation of its transmission shafting is affected by the "machine-soil" interaction environment, especially the tire-soil interaction. Therefore, a load transfer model of a tractor plowing operation composed of a drivetrain model, tire-soil interaction model, and tractor dynamics model was established, to analyze the load characteristics of the transmission shafting. For verifying the proposed model, the field plowing process was carried out experimentally. The driving wheels and shafting were discussed as influenced by the slip rate variation in the tire-soil interaction model. The fitting distribution characteristics of cycle average and range of transmission shafting in the rain-flow domain were obtained. The results showed that the established model can accurately simulate the speed and dynamic load characteristics of the tractor plowing operation. The driving wheel loads increased with the increase of slip rate except for the motion resistance. When the slip rate exceeded 25 %, loads of the transmission shafts changed steadily. The reliability of fit R2 of the statistical distribution for transmission shafting load was greater than 0.94. The mean and variance of rear-drive half shaft torque were the largest, where fatigue failure was more likely to occur. The above theoretical model and results provide practical guidance for structural optimization design, fatigue durability analysis and reliability loading test of the tractor drivetrain.