Research On The Mechanism Of Action And Performance Of A Precision Spreading Device For Wind-sand Soil Improvement Materials

At present,sandy soil improvement is one of the most effective measures in sandy soil management.By applying soil modification and water retention materials and mixing them with sandy soil in a certain proportion,the texture and physicochemical properties of sandy soil can be effectively improved.Mechanisation can improve operational efficiency and reduce costs,but precise control of the amount of material applied is one of the key technologies to ensure the improvement effect.To further solve the problems of low mechanisation rate and uneven spreading of sandy soil improvement,and to improve the mechanised spreading efficiency of improved materials,this thesis designs a precise variable full-width material spreading device,studies its working principle and analyses the uniformity of spreading,which is of great significance for the development of highefficiency sandy soil improvement equipment.Based on the analysis of the working process and structure of the full-width material spreading device,this thesis investigates the working process of the full-width material spreading device,takes the material particles as the object of study,measures the physical and mechanical parameters of the particles and analyses their movement and force,carries out the spreading simulation of the material particles and optimises the working parameters of the device through indoor tests.The main elements and conclusions are as follows:(1)Measurement and calibration of physical and mechanical parameters of materialsWhen modelling material particles,the contact parameters and contact model parameters can directly affect the accuracy of the simulation results.To ensure the accuracy and realism of the established particle models,the commonly used modified materials straw powder and biochar were selected as the study objects and their physical and mechanical property parameters(parameters such as density,particle size distribution,triaxial dimensions,moisture content and rest angle)were measured.(2)Design of the material spreading deviceBased on the analysis of the structure and working principle of existing sand fixing machinery and precision fertiliser application machinery,a precision variable full width material spreading device is designed.By establishing a mechanical model of the material particles in the spreading process,the movement analysis and force analysis of the material particles are carried out,and the structural and operating parameters of the spreading device are determined according to the ratio of the material to the wind-sand soil and the required fertiliser application volume.(3)Simulation of plant operating effects and analysis of material particle movementAccording to the design of the device and the physical and mechanical parameters of the material particles,the simulation model of the material particles and the spreading device is established,the contact model is determined and the relevant parameters are set,and the simulation test study of the material spreading process is carried out based on the discrete element method.The uniformity of spreading is also relatively poor.The force,velocity and displacement of the individual particles were also analysed to obtain the particle movement pattern.(4)Experimental verification of the operational effectiveness of the deviceA quadratic regression model was developed to investigate the effect of the interaction between the three factors(travel speed,speed and speed)and the test index(coefficient of variation of the distribution),to optimise the objective function with constraints on the range of values of the three factors and to verify the optimal results.The average relative error after optimisation was 8.01%.The optimised operating parameters of the device provided a significant improvement in the uniformity and reliability of the fertiliser spread.In this thesis,a spreading device is designed and developed specifically for wind-sand soil improvement machinery,and optimizes its working parameters.Simulation and experiments have shown that the spraying device has good uniformity and continuity of spraying,providing a foundation for the mechanized operation of wind sand soil improvement.