To address the fact that existing studies may not be able to accurately describe the discrete element parameters of the soil during the potato harvesting period and to improve the accuracy of the potato harvesting equipment simulation studies, this study was conducted on the soil around the harvested potato tubers in the field. The simulation parameters of the discrete element model of soil were determined by the soil stacking angle test and soil block shear crushing test with the actual test measurements as the target. Based on a series of experimental designs, the factors affecting the stacking angle were the static friction coefficient and the rolling friction coefficient between soil particles; and the rolling friction coefficient between soil and steel. The factors affecting the maximum shear damage force were normal stiffness and shear stiffness per unit area. The quadratic regression equations were established and solved to obtain the optimal discrete element simulation parameters. The results can provide more realistic and reliable parameters for the construction of soil simulation models of potato fields during harvesting and for the discrete element simulation of soil-touching components of potato harvesting equipment. It can also further enrich the parameter data of soil discrete element simulation models and provide a reference for related research

Potato stem removal is one of the critical technical problems of potato mechanized harvesting; it directly affects the quality of potato harvesting and potato storage. There have been several studies on potato stem removal mechanisms. In practice, however, it was found that the potato stem removal rate was greatly influenced by the posture of the stem before it entered the removal mechanism. In this study, we designed a potato stem posture adjustment mechanism consisting of elastic curtains. A test rig was built to investigate the effect of curtain height, curtain width, and curtain suspension height on potato passage rate and potato stem removal rate. The Box–Behnken design (BBD), combined with the response surface method, was used to conduct the test. The optimal construction and installation parameters for each elastic curtain were determined as 278.93 mm for the curtain height, 20 mm for the curtain width, and 260 mm for the curtain suspension height. The predicted values of potato passage rate and potato stem removal rate under the optimal parameters were 92.36% and 82.83%, which were consistent with the validation test results. Based on the optimization results, a rigid-flexible coupled simulation model for a potato stem transported-posture adjustment process based on Abaqus and Adams was constructed. The maximum impact of the elastic curtain of the stem posture adjustment mechanism on the potato stem was 15.91 N and caused the stem to spring back. The projection angle β′ of the stem posture angle in the xoz plane before posture adjustment was 19.07°, and the β′ of the stem after posture adjustment was 87.18°. At this time, the stem was basically parallel to the rod of the separating sieve and had a high probability of falling from the gap of the bar to complete the removal of the stem. Overall, the stem transport position adjustment mechanism effectively adjusted the stem transported posture and improved the stem removal rate in potato mechanical harvesting.

The uneven sowing of wheat on ground covered with rice straw in the rice–wheat rotation area in the middle and lower reaches of the Yangtze River has become a serious problem. Therefore, a test bed for throwing soil after sowing with a wide wheat seed belt was designed, which could complete the functions of straw crushing, straw lateral concentration and uniform sowing at one time. The discrete element simulation model of throwing soil after sowing with a wide wheat seed belt was established with rotary blade shaft speed, soil guide plate angle and soil retaining plate angle as variables. Taking the variation coefficient of wheat sowing depth and variation coefficient of sowing lateral uniformity as evaluation indexes, the effects of three variables on sowing uniformity were analyzed by single factor test and Box–Behnken test. The results of single factor test observed that when the rotating speed of rotary blade shaft was 260–300 rpm, the angle of soil guide plate was 36°–48°, the angle of soil retaining plate was 58°–74° and the experiment of utilizing a soil throwing and covering device with a wide seed belt after sowing revealed a good consistency of sowing depth and lateral uniformity effect. The Box–Behnken simulation experiment showed that the primary and secondary factors affecting the variation coefficient of wheat sowing lateral uniformity were the angle of soil guide plate, the rotation speed of rotary blade shaft, the angle of soil retaining plate and the angle of soil guide plate. When the rotation speed of rotary blade shaft, the angle of soil guide plate and the angle of soil retaining plate were 282.1 rpm, 42.4° and 65.5°, respectively, the soil throwing and covering device after sowing has the best seed-homogenizing effect. At this time, the variation coefficients of sowing depth and lateral uniformity in simulation test and field verification test were 4.35% and 4.57%, respectively, and 12.46% and 12.73%, respectively. The results of field verification test were basically consistent with those of the simulation test, which proved that the results of applying discrete element methods to optimize the soil-throwing device after sowing with a wide seed belt were credible. This study could provide a theoretical reference for the structure optimization of a soil-throwing device after sowing with a wide seed belt.

The suspension velocity is the core of the cleaning and sorting mechanisms that utilize a combination of a fan and vibrating sieve. To investigate this, various experimental subjects, such as peanuts with different kernels and clay-heavy clods in different states, were used. The experiment involved simulating the suspension velocity of materials through numerical calculations using fluid dynamics and particle discrete element coupling. The Eularian model was employed to study the coupled gas-solid two-phase flow. The experiment measured the suspension velocities of single and double kernel peanuts, which were found to be 8.34~9.40 m/s and 8.13~9.51 m/s, respectively. Under 20.4% water content and lumpy conditions, the suspension velocities of smaller clods, side by side clods, and larger clods were 12.61~14.30 m/s, 14.16~15.76 m/s and 16.44~18.72 m/s, respectively; under 20.4% water content and smaller clods, the suspension velocities of lumpy and strip of clods were 12.61~14.30 m/s, 11.90~14.13 m/s, respectively; under lumpy and smaller clods, the suspension velocity at 17.6%, 20.4%, and 23.9% water content ranged from 12.38 to 14.20 m/s, 12.61 to 14.30 m/s, and 12.62 to 14.49 m/s, respectively. The simulations showed that the suspension velocity for different types of peanuts, clod sizes, shapes, and water contents was less different from the actual experiments. Specifically, the relative errors in suspension velocity for single-kernel peanuts, double-kernel peanuts, smaller clods, side-by-side clods, larger clods, lumpy clods, strips of clods, and clods with 17.3%, 20.4%, and 23.9% water content were 1.2%, 4.1%, 0.4%, 2.0%, 4.4%, 0.4%, 5.1%, 5.4%, 0.4%, and 1.9%, respectively, compared to actual experiment measurements. The results indicate a significant difference in the suspension velocity between peanuts and clay-heavy clods, which can be distinguished from each other based on this difference. Furthermore, the simulation results have been found to be consistent with the experimental results, thus verifying the feasibility of measuring the material suspension velocity using CFD-DEM gas-solid coupling.

In this study, we quantified and analyzed the root-cutting process of garlic with a test bench with pressure sensors on the basis of the comparative analysis of various information perception methods. On the basis of the output value of the pressure sensor, the force curve of garlic roots was plotted, and the double round blade cutting module is optimized on the basis of the force curve diagram. The innovative proposal of slotted round blades for garlic root cutting is presented here. The round blade diameter is 110 mm, the center distance is 100 mm, the blade thickness is 1 mm, and the blade speed is 1200 r/min. According to the analysis of the force curve, it was found that the slotted round blade with the slanted blade could generate a strong thrust to cut the roots. The cutting effect was better and the cutting surface of the roots was straight. The slotted blade meets the need for cutting garlic roots.

When wide-width sowing wheat after rice stubble (WRS) in a rice-wheat rotation area, there is a problem of poor uniform of seed distribution. To solve the problem, this study designed the seed distribution plate (SDP) structure and optimized its critical structure parameters. Firstly, combined with the operating principles of the wide-width seeder and the agricultural standards for WRS, the main structural parameters affecting seed movement were determined by a theoretical analysis of seed grain dynamics and SDP structure. Secondly, the operational performance of six different structures of SDP under different structural parameters was compared using discrete element simulation technology. The structure of SDP most suitable for WRS wide-width seeding and the value ranges of key structural parameters that have a significant impact on the coefficient of the variation of seed lateral uniformity (CVLU) were determined. Finally, the pattern and mechanism of the influence of key structural parameters of SDP on the CVLU were analyzed. The optimum parameter combination was obtained and a field validation test was conducted on this. The results showed that the anti-arc ridge and arc bottom structure (S6) is more suitable for the agronomy standards of WRS wide-width seeding. The chord length of ridge, installation inclination, angle between the chord and tangent of the end of ridge line (ACT), span, and bottom curve radius are determined as the key structural parameters affecting the CVLU, and there is a lower CVLU (42.8%) when the ACT is 13°. The primary and secondary order of the influence of each factor on CVLU is the chord length of the ridge, span, installation inclination, and bottom curve radius. The corresponding parameter values after optimization are 140 mm, 40°, 75 mm and 50 mm, respectively. A field test was conducted on the SDP after optimizing parameters, and the CVLU was 30.27%, which was significantly lower than the CVLU before optimization.