Crop straw chopping and returning technology has gained global implementation to enhance soil structure and fertility, facilitating increased crop yield. Nevertheless, technological adoption faces challenges from inherent limitations in machinery performance, including poor chopping and returning quality and high energy consumption. Consequently, this review first presented a theoretical framework that described the mechanical properties of straw, its fracture dynamics, interactions with airflow, and motion characteristics during the chopping process. Then, based on the straw returning process, the chopping devices were classified into five types: the chopped blade, the chopping machine, the chopping device combined with a no-tillage or reduced-tillage seeder, the chopping and ditch-burying machine, the chopping and mixing machine, and the harvester-powered chopping device. Advancements in spreading devices were also summarized. Finally, six key directions for future research were proposed: developing an intelligent field straw distribution mapping system, engineering adaptive self-regulating mechanisms for chopping and returning equipment, elucidating the mechanics and kinematics of straw in the chopping and returning process, implementing real-time quality assessment systems for straw returning operations, pioneering high forward-speed (>8 km/h) straw returning machines, and establishing context-specific straw residue management frameworks. This review provided a reference and offered support for the global application of straw returning technology.

In view of the prominent problem that nonlinear vibration of a belt conveyor can easily occur during the vertical grain-conveyance process due to the coupling effect of airflow clamping and traction of the conveyor belt, which seriously affects the efficiency and stability of conveying materials by the belt conveyor, a method of solving the vibration analysis of the vertical lifting section of the bulk grain belt unloader by using nonlinear vibration is proposed. Firstly, based on the laminated plate theory, the vertical lifting belt and the grain material clamped by the belt are laminated. The nonlinear vibration differential equation of the vertical lifting section of the bulk grain-carrying ship unloader is established by elastic–plastic mechanics, and solved by perturbation theory and Galerkin discrete analysis. The vibration response curve and structural natural frequency of the vertical lifting section of the bulk grain-carrying machine are obtained by numerical solution, and the influence of the volume content of the clamped material on the vibration response and structural natural frequency of the lifting section is analyzed. This study provides theoretical support for the design of pressure-supply parameters, overall structure and operation parameters of the subsequent entrainment ship unloader, promotes the rapid development of the entrainment ship unloader, provides theoretical support for the design, manufacture, later operation, and maintenance of the entrainment ship unloader, and thus provides equipment and technical support for building an efficient and intelligent port.

During the vibration crushing of wheat bran, an impact-blocking effect occurred between the grinding media and wheat bran powder. Experimental results showed that the impact depth exhibited quadratic relationship with respect to particle size, while the acceleration and damping coefficients followed the order: fine powder > coarse powder > uncrushed bran > micro powder. Increasing the diameter of the grinding media enhanced the impact depth by 81.10% for uncrushed bran and by 40.41% for coarse powder, but reduced acceleration by 45.35% and 29.56%, respectively. Damping coefficients positively correlated with grinding media diameter but negatively with cylinder diameter. Material layer thickness demonstrated threshold-dependent bidirectional regulation, peaking at 40 mm, with maximum damping difference rates of 20.40% for uncrushed bran and 17.67% for coarse powder. Drop height linearly influenced the impact depth, while showing cubic relationships with both acceleration and damping. Both parameters were minimized at 500 mm. Sensitivity analysis identified grinding media diameter as the primary factor affecting damping coefficients, revealing the sensitivity hierarchy: grinding media diameter > drop height > material layer thickness > cylinder diameter. This study provided a theoretical foundation and experimental support for optimizing the vibration superfine crushing efficiency of wheat bran.

Effects of low temperature and washing on the vibration superfine grinding performance of wheat bran