Machinery-plant-paddy soil coupling model based numerical simulation method of mechanical transplanting process of big rice seedling

The working conditions are complex in rice seedlings mechanical transplanting process, and some parameters of the working process are difficult to measure. The interactions among machinery, seedlings and paddy soil are unclear because of a lack of a powerful analysis methods, and this hampers improving the quality of big rice seedling transplantation. A dynamics model of the machinery-plant-paddy soil coupling system was established using the computational fluid dynamics (CFD) method to analyse the transplanting process. The reliability and accuracy of the numerical model were verified by the soil bin test. The results simulated showed that the transplanting impact load is the main cause of stem damage, and the stem base is the vulnerable area. The maximum working load of seedling needle are significantly affected by root morphology, hierarchical structure and bond strength with soil. The proposed numerical simulation method reflected the variations in physical and mechanical parameters during the transplanting process. It provides an effective method for the visualization and analyses of the interaction and seedling- damage mechanisms of the complex paddy field working system.