In view of the lack of accurate model in the discrete element study during straw comprehensive utilization (crushing, mixing, and baling), wheat straw was taken as the research object to calibrate the simulation parameters using EDEM 2023. The intrinsic and contact mechanical parameters of wheat straw were measured, and a test of the angle of repose (AOR), extrusion test and bending test were carried out. On this basis, a discrete element model (DEM) of hollow flexibility by using cylindrical particles was developed. The optimal combination of contact mechanical parameters was obtained through AOR tests based on the Box–Behnken design (BBD), coefficients of static friction, rolling friction, and restitution between wheat straw and wheat straw-45 steel are separately 0.227, 0.136, 0.479, 0.271, 0.093, and 0.482, AOR is 18.66°. Meanwhile, optimal combinations of bond contact parameters were determined by the BBD. The calibrated parameters were used to conduct extrusion and bending tests. Results show that the average values of peak extrusion force and peak bending pressure are 23.20 N and 3.92 N, which have relative discrepancy of 3.25% and 3.59% compared to physical test measurements. The results can provide model reference for the optimization design such as feed processing equipment, baler, and mixer.

Design and optimization of the seedling needle and push device for a mechanical transplanter of seedlings from bowl-type trays made of paddy straw

Mechanical characteristics of rice seedlings under wind stress

Addressing the issues of poor performance and low single-seed rate during seed filling and cleaning for corn, an airsuction roller precision dibbler was designed, and its main structure and working principle were elaborated. Based on the structure of the seed metering disk and the tri-axial dimensions of corn seeds, an auxiliary filling type hole boss was designed with a radius of 4 mm and a thickness of 1.5 mm. A sawtooth-type seed cleaning device was also designed, with an installation angle greater than 3° and a serrated chamfer less than 62.1°. By coupling the Discrete Element Method (EDEM) with Computational Fluid Dynamics (CFD), the flow field structure and seed metering performance were simulated and analyzed, examining the movement states of the seed population and individual seeds during the processes of filling, cleaning, carrying, and initial seed dropping. The variation patterns of the internal flow field pressure and fluid velocity of the seed metering device under different negative pressures and operating speeds were studied. Through the construction of a test bench and single-factor and three-factor orthogonal experiments, along with multi-objective optimization methods, the primary and secondary factors affecting the qualification index were determined. The optimization results showed that when the flow field negative pressure was 3.52 kPa, the operating speed was 5.81 km/h, and the suction hole diameter was 4.15 mm, the qualification index of the seed metering device was 93.2%, the missed seeding index was 3.3%, and the multiple seeding index was 3.5%. An adaptability test was conducted to verify these results, revealing that the qualification index for all three varieties of corn seeds exceeded 92.4%, the missed seeding index was less than 3.7%, and the multiple seeding index was less than 3.9%, satisfying the precision seeding requirements for corn seeds.