Considering the problems of a low soil fragmentation rate and low straw mulching rate in the traditional rotary tiller tillage mode in the saline-alkali land, the layered stubble and soil crushing rotary tillage knife was designed, and the key structural parameters were determined by the analysis of rotary tillage knife-soil-straw movement. The soil-straw movement behavior in saline-alkali land under different working parameters of rotary tillage was analyzed, and the discrete element modeling of soil-straw-rotary tillage in saline-alkali land was established. In addition, the dynamic process of soil-straw aggregate fragmentation in saline-alkali land from a microscopic perspective was systematically explored. Combined with experimental optimization analysis, the optimum working parameters of the saline-alkali rotary tiller were obtained with a forward speed of 2.02 km/h, a working depth of 178.83 mm, and a rotation speed of 324.48 r/min. To verify the field performance of the machine, the soil fragmentation rate, straw burial rate, and tillage depth stability were chosen as test indices for the field trial. The average soil fragmentation rate was 91.85%, the average straw returning rate was 91.09%, and the average stability of tillage depth was 91.12%, indicating that the designed rotary tiller can effectively improve soil crushing and straw burial in saline-alkali land and meet the basic requirements of high-performance seedbed preparation in saline-alkali land.

In this study, a simulation model of peanut pod particles during harvest in saline soil was tested to calibrate contact parameters. Discrete meta-fill models of peanut pods were generated by a 3D meter and EDEM software. The range of values of contact parameters for peanut pods was measured by conducting collision and other tests using a homemade test rig. The parameters that affect the significance of the simulation process of stacking angle were screened by the Plackett-Burman experiment, the steepest ascent experiment, and the Box-Behnken experiment. An optimization test determined the optimal simulation model parameters: The peanut pods had a Poisson’s ratio of 0.386 and a shear modulus of 3.04 MPa. The coefficient of recovery for pods-pods collisions was 0.335, the coefficient of static friction was 0.854, and the coefficient of rolling friction was 0.346. The coefficient of recovery of collision between the pods-65Mn steel was 0.339, the coefficient of static friction was 0.589, and the coefficient of rolling friction was 0.159. The test results showed a relative error of 0.42% between the stacking angle bench and simulation tests. The results can provide data support for studying the discrete metamaterial characterization of peanut pods.

Crops are prone to lodging with the decline of stem moisture and the intervention of other factors in the mature harvest period, such as garlic, which is difficult to harvest mechanically. To solve this problem, the plant-correcting reel for harvesting lodging garlic plants, bumped and deformed with plants many times to pull and lift them into a conveyor, was proposed in this study. This study analyzed the motion trajectory equation and key influencing factors of the reel and defined the lifting and plant-correcting stages as three processes of contact, stirring and release. For example, the contact deformation model and system energy equations were established in the contact process. Besides, in the stirring process, the garlic plant-correcting conditions were established through the dynamic simulation test analysis of garlic seedling trajectories and the deflection model of garlic stem was constructed. Furthermore, in the release process, the expressions of rubber bars rotation and garlic plant offset bending curvature were constructed and the optimal number and distribution form of bars were determined. Meanwhile, the mechanism and key operating parameters of the auxiliary lifting mechanism of the divider were established. Through the single-factor test, the influence of reel speed, forward speed and reel height on the success feeding rate was analyzed under different bars distribution forms; Through multi-factor experiments, the interaction contour map of various factors was constructed. When reel speed, forward speed and reel height were 3 rad/s, 3.5 m/s, and 540 mm, the feeding success rate was 98.73%. The optimization factors were tested and verified, which met the operational requirements of a high feeding success rate and low loss rate of garlic harvest. This study combines laboratory virtual as well as field experiments and analyzes of trajectory of bars, contact deformation and deflection model of garlic plant, and reel rotation and garlic plant offset bending curvature to solve the problem of garlic lodging mechanized harvest and yield reduction.

Considering the problems of low soil crushing rate and poor straw mulching performance of the traditional rotary tiller on saline-alkali soils, a two-axis layered rotary stubble cutter for saline-alkali soils with front-axis positive rotation of the front axle and rear-axis counter-rotation of the rear axle was developed, focusing on the kinetic properties of the straw and soil under positive and counter-rotation. In addition, the most important structural parameters and the arrangement of the front-axis stubble cutting knife and the rear-axis return knife were analyzed and determined. Hertz-Mindlin with bonding was used to create a discrete element model of the agglomerate of implement, straw and soil. The forward speed, horizontal distance and vertical distance were used as test factors, and the straw return rate and soil fragmentation rate were used as test indexes to analyze the straw-soil transport law under different operating parameters from a microscopic point of view, and then Design-Expert was used to conduct the test 1.07 km/h, horizontal distance of 569.55 mm, vertical distance of 176.59 mm. To validate the performance of the two-axis, layered rotary tiller, a field trial was conducted and the results show that the straw return ratio was (91.59±0.41)%, soil fragmentation ratio was (91.90±0.29)% and tillage depth stability was (91.52±0.46)%, which met the requirements for peanut seedbed preparation on saline-alkali land.

During combined peanut harvesting operations, the separating device plays a crucial role in determining peanuts’ damage rate and impurity content. In order to enhance the quality and efficiency of peanut harvesting, this study investigates the separating device of a two-ridge and four-row half-feeder combine harvester. Firstly, the operating principle of the separating device was analyzed, and a combined air-and-screen separating device was selected. Secondly, based on the movement state of peanut pod impurities in different sections of the separating device surface, the theoretical analysis of peanut pod impurity movement was carried out, and the peanut pod impurity dynamics model was constructed. At the same time, CFD software was used to analyze the airflow field inside the separating device. Moreover, the test factors affecting the separating effect were explored: fan wind speed, separating device surface inclination, and vibration frequency. The optimal working parameters of the device were determined as follows: a fan wind speed of 8.9 m/s, a separating device surface inclination angle of 8.3° concerning the horizontal, and a separating device vibration frequency of 7.2 Hz. The impurity content rate of the peanut pods was 1.48%, and the damage rate of the separating device was 1.61%. Finally, the impurity content of peanuts in the validation experiment was 1.53%, and the peanut damage rate was 1.68%. The effectiveness of the separating device operation was verified through field tests. The potential for further research on peanut harvesters is highlighted based on the findings of this study.