Discrete element modeling and physical experiment research on the biomechanical properties of banana bunch stalk for postharvest machine development

The biomechanical properties of plant stalk play an important role in the increase of crop production, the development of post-harvest mechanical equipment and the comprehensive utilization of biomass resources. Under the action of external forces in different forms and different loading directions, there are differences in the internal biomechanical properties of the stalk. The cutting force of some plant stalks has been reported in the literature, which is helpful to understand the mechanical properties of the stalks of field crop varieties, but the report on the biomechanical properties of banana bunch stalk is still blank. In the current research, we have established discrete element mechanical models of banana bunch stalk by the combination of discrete element analysis and physical experiment testing. The shear, tension, compression and bending mechanical properties of banana bunch stalk of different varieties (Brazilian banana and plantain banana), wet basis (WB) moisture contents of 93% and 84%, and internode positions (from 1 to 6) were studied. According to the experimental results, the established discrete element mechanical models were optimized. Our research provides new insights on how to use the discrete element method to analyze and research the biomechanical properties of banana bunch stalk, and visualize the micromechanics of banana bunch stalk and its nonlinear damage behavior. In addition, our results clearly show that the mechanical strength and elastic modulus of banana bunch stalk increase with the increase of the internode position on the stalk, and decrease with the decrease of the stalk moisture. For all the biomechanical properties of banana bunch stalk, the two factors of internode position and moisture content have a significant effect (P 0.05), while the effect of the factor of the variety is not significant (P 0.05). These results provide useful information about the evolution of banana bunch stalk biomechanical properties and the mechanism of deformation and failure, and provide a basis for the increase in banana production, the design and development of postharvest machinery, and the comprehensive utilization of agricultural residual biomass resources.