Abstract: Aiming at the problems of breakage and the difficulty in load spectrum measurement of the soil-engaging components of agricultural machinery, the fatigue strength of the soil-engaging components of agricultural machinery was studied under rated working conditions, the method of fatigue analysis of a bidirectional coupling based on DEM and MFBD was proposed. Taking the well-making machine as an example, a rigid-flexible coupling dynamic model of the cave-forming drill assembly device was constructed by using the FFlex method. On this basis, it was further coupled with the discrete element simulation to simulate the interaction process between the cave-forming drill and soil, and the dynamic working load spectrum of the cave-forming drill was extracted.The fatigue life of the cave-forming drill was predicted by the fatigue simulation software based on the relevant theory of fatigue analysis. The results indicate that the weak area of fatigue strength of the cave-forming drill is located near the small end of the conical surface, the simulated prediction of the failure area is basically consistent with the actual fracture position, and it verifies that the fatigue analysis method of bidirectional coupling based DEM and MFBD can accurately predict the dynamic response characteristics and fatigue life of the cave-forming drill, and provide a valuable reference for its fatigue strength design.
Key words: agricultural machinery; soil-engaging components; discrete element method（DEM）; multi-flexible body dynamics（MFBD）; well-making machine; modeling method of the non-linear finite element flexible body（FFlex）