Abstract:In response to the ambiguous understanding of the interaction mechanism between mechanical components and tea stem with the imprecision of tea stem model in the harvesting process of famous tea, focusing on tea stem, a novel approach termed binding enhancement was proposed to establish a three-layer discrete element simulation model for tea stem. The maximum shear force was used as the evaluation index with the factors of the normal contact stiffness of the xylem-xylem, the tangential contact stiffness of the xylem-xylem, and the bonding radius. The Plackett-Burman experimental design was used to select the significant influencing factors on the maximum shear force. The calibration range of significant parameters was narrowed down by the steepest climbing test, and the optimal combination of two models was further obtained through Box-Behnken test and variance analysis. Subsequently, the calibrated parameters were utilized to construct comprehensive models for tensile and puncture simulations, which was systematically compared and analyzed against corresponding physical experiments.The results indicated that the xylem-xylem normal contact stiffness, xylem tangential contact stiffness and bond radius had a significantly effect on the mechanical properties of the stem. The optimal combination was determined to be 3.447×1011 N/m3, 3.536×1011 N/m3, and 4.404×10-5 mm, respectively. The tensile and puncture verification experiments displayed relative errors not exceeding 3%, and the trend in stem force variation demonstrated substantial consistency. These results underscored the feasibility and accuracy of the calibrated and optimized parameters, thereby laying a solid theoretical foundation for numerical simulation studies pertaining to tea stem system.
