In order to study the effect of moisture content on the static friction coefficient of peanut pods, taking the main peanut varieties Wanhua 2 and Dabaisha 171 as experimental materials, the moisture content of peanut pods was regulated by DGF30/7-IA electric blast drying oven. The static friction coefficient of the peanut pod was measured by the static friction coefficient inclinometer based on the principle of statics. The effects of peanut varieties, contact materials, and pod moisture content on the static friction coefficient of peanut pods were analyzed by a single factor test. The results showed that the variation trend of the friction coefficient between peanut pods of different varieties and Q235 steel plate, large hole sieve, and small hole sieve was the same at all levels of water content. The static friction coefficient of the peanut pod increases with the increase in water content. The variation range of friction coefficient between Wanhua 2 and Q235 steel plate, macro sieve, and small sieve under different water content (10.18%, 1357%, 16.28%, 20.66%, and 25.85%) is 0.388-0.611, 0.494-0.819, and 0.553-0.975 respectively. The variation range of friction coefficient between Dabaisha 171 and Q235 steel plate, macro sieve, and small sieve under different water content are 0.42-0.622, 0.608-0.822, and 0.619-0.892, respectively. The variation trend of the friction coefficient between peanut pod and different contact materials is the same at all levels of water content. The static friction coefficient of Dabaisha 171 is less than that of Wanhua 2, and the fluidity of the peanut pod of Dabaisha 171 is better. The results can provide a reference for the simulation parameter setting and optimization design of peanut circulating drying equipment.

In order to ensure the accuracy of the parameters used in the simulation test of peanut pods, the study uses the method of combining actual physical test and simulation test to calibrate the discrete element simulation parameters. First of all, the basic physical parameters of peanut pods (including dimensions, density, moisture content, bulk density, elastic modulus, Poisson wave and shear modulus) are measured through actual physical experiments, and the simulation is determined based on the results of various physical quantities measured by actual physical experiments. The value range of the test parameters is carried out, and the PlackettBurman test is carried out. The factors that have a significant influence on the stacking angle are selected: peanut podpeanut pod static friction coefficient, rolling friction coefficient, peanut podsteel plate static friction coefficient. The value range of the significant factor is further determined by the steepest climb test. BoxBehnken test is carried out to establish the quadratic regression equation between the accumulation angle and the significant factor, and solve the equation with the actual physical test accumulation angle (31.63°) as the target value, and obtain the best simulation parameters:the static friction coefficient and rolling friction coefficient of peanut pods, and the static friction coefficient between peanut pods and steel plates are 0.74, 0.24 and 0.58, respectively. Finally, a simulation test on the best simulation parameters determined after the experimental analysis is performed, and an independent sample T test on the obtained simulation value and the actual test value is performed, with P>0.05, which shows that there is no significant difference between the actual test accumulation angle and the simulation test accumulation angle, and the relative error is 2.877%,  the accuracy of the simulation test is also verified. By comparing the methods and test results used in the calibration of other material parameters, it further shows that the calibrated parameters can provide references for related research.

In order to solve the problems of large loss rate and high damage rate of 4UZL-1 sweet potato combine harvesters during the operation process, the working principle of 4UZL-1 sweet potato combine harvester was described in detail based on the analysis of its overall structure, the conveyer mechanism of arc grid handover scraper chain was designed, and the working parameters were determined. Relying on the machine and sweet potato planting mode, the arc grid handover scraper chain conveying test bench was built. With potato tuber of loss rate and damage rate in the process of transferring of potato tubers as the main evaluation index, the single factor bench test was carried out with the angle of excavating and conveying mechanism, the angle of scraper chain conveying, the speed of excavation and conveying mechanism, the speed of scraper chain conveying, scraper angle and arc grid installation distance as test factors. The significance of the influence of each factor on each performance index, the influence rule, and the cause were analyzed. The test results showed that the angle of excavating and conveying mechanism, the conveying angle of scraper chain, the speed of excavating and conveying mechanism, and the conveying speed of scraper chain had significant impacts on the performance indexes, while the angle of the scraper and the installation distance of the arc grid had no significant impact on the performance indexes. When the angle of excavating and conveying mechanism was 24°, the conveying angle of the scraper chain was 60°, the speed of excavating and conveying mechanism was 1.15 m/s, and the conveying speed of the scraper chain was 0.69 m/s.The arc grid transfer scraper chain conveyor mechanism was more effective. The loss rate and the damage rate were 075% and 013%, respectively. The research results can provide a reference for the structural improvement and parameter optimization of the sweet potato combine harvester.

In view of the lack of research on the by-product management specifications of agricultural machinery research institutes in China, in order to formulate the by-product management specifications in line with its characteristics and reduce the loss of state-owned assets, the characteristics of the by-product production of agricultural machinery research were analyzed and put forward based on the description of the by-product management of planting agricultural research. The first characteristic was that the production of scientific by-products of agricultural machinery was not targeted at agricultural breeding. The second characteristic was the small amount of research by-products produced. The third characteristic was that agricultural machinery scientific research by-products damage was difficult to reach the requirements of marketing. The fourth characteristic was that there were fewer scientific research by-products such as scientific research machines or spare parts that can be marketed. The fifth characteristic was that agricultural machinery products on the market sales need qualification appraisal or certification of the subject was not scientific research units. And the management measures of scientific by-products in representative agricultural machinery research institutes were analyzed. New measures were put forward, such as the need to clarify the subject of responsibility for the management of scientific research by-products, ledger registration, disposal principles, methods and procedures, requirements for revenue and expenditure management, supervision and “red line”. It can be used as a reference for other domestic agricultural machinery research institutes to improve the management of scientific by-products.