Bionic threshing component optimized based on MBD-DEM coupling simulation significantly improves corn kernel harvesting rate

The most widely used rigid threshing component (RTC) currently has a constant problem with high kernel damage rates. Inspired by the seldom occurrence of kernel damage in manual threshing operations, this study designed a bionic threshing component (BTC) by using the human thumb as a bionic prototype. BTC can imitate the thumb's real-time profiling capability on the shape of the corn ears, thereby reproducing the thumb's "flexible profiling impact" method of applying force, significantly different from the "rigid impact method" of RTC. Based on EDEM and RecurDyn software, the MBD-DEM coupling simulation model of the threshing operation was constructed. Through the coupling simulation experiments, the influence law of the BTC core design parameter k (bionic joint torque elasticity coefficient) on the kernel harvesting rate., threshing rate and damage rate was revealed. Meanwhile, the optimum value of k (2.08 KN center dot mm/degrees) was derived by modelling the k-eta regression. Bench comparison and simulation accuracy verification experiments showed that BTC operated with optimal k values can increase corn kernel harvesting rates by 0.87%-1.57%, compared to RTC. (BTC was able to achieve the highest kernel harvesting and threshing rates of 98.61% and 98.97%, respectively, with breakage rates as low as 0.16%). Meanwhile, the computational results of the MBD-DEM coupling simulation model established in this study were not significantly difference from the bench experiment (P > 0.05). To sum up, this study can provide a new mechanism design idea and parameter optimization method for the development of threshing components.