| The ridger is one of the most important soil contacting part of combined rototilling-tillage machine,multi-function ridger,fertililization machine and so on., and be used widely in planting, fertilization and drainage. An optimized ridger functioning properly can significantly reduce soil resistance and energy consumption, therefore multi function machine has to be promoted.Soil resistance during soil machine contact has become a distinctive feature in agriculture. Until now, significant progress in theory and technology has been made by many scholars at home and abroad in researching soil resistance reduction by agricultural machinery. In recent years, the study of bionics has made made a serious progress in reducing traction, soil resistance and adhesion. Researchers found that the surface of organism have a function that could reduce resistance in soil. Surface morphology is closely related to resistance reduction. Based on the bionics and the prototype of wild boar proboscis, this research focuses on the bionic design of the ridger.In our research group, a lot of work on wild boar which forms god basis for this research has been done, especially on 3-D geometrical modelling of the animal. In the 3-D geometrical modelling, analysis on wild boar dimensions, surface curvature, brightness, sectional curvature, cross analysis of 5 kinds of curves. From the point clouds and the surface curvature normal distance, it was found that the normal distance between the point clouds and surface curvature of proboscis of the wild boar was 2.817mm, the smallest distance was -3.669mm and average -0.3172mm. 81.68% of the point clouds had an error within the range of -1.237mm~1.195mm. The surface curvature analysis gave the following results: the whole surface curvature did not change much, least surface curvature was -0.0461㎜-1 , maximum surface curvature was 0.0919㎜-1, and the average was on the proboscis. The minimum curvature was just below the eyes of the wild boar. As for the brightness, the highest intensity was on the proboscis, 2 sides and crest of the nose. The front part of the proboscis and the 2 sides of the nose had greatest curvature and normal distance., and the average was on the crest of the nose. From the curvature analysis of the 8 sections of the wild boar proboscis, the front part had some special characteristics like the change of curvature was totally different from the rest, the last 3 curves also showed a lot of similarities, and in this part the surface curvature is similar too. From cross analysis results, the front part of the proboscis and the crest of the nose had special geometry, maybe it is related to its ability to reduce resistance when penetrating into the soil, surface curvature of the proboscis was smooth and the quality was just good. In addition to one ordinary ridger, analyses of the 5 curves of the wild boar proboscis was done, and the main kinds and dimensions of the ridger were calculated. The best kind of bionic ridger was chosen. The bionic ridger had the following dimensions: width 150 mm, surface height 35 mm, length 170mm, angle of ridger wing 60°,width of ridger wing380mm, angle of soil penetration25°, soil failure angle10°Indoor soil bin experiment was designed, moisture content controlled at 20.8%, and every time the soil was compressed to about 74 N/cm2. Soil resistance was measured for 5 different bionic ridgers and one ordinary one at 5 different speeds. From the results of the experiment, the soil resistance decreased in the following order respectively: bionic ridger E, bionic ridger D, ordinary ridger F, bionic ridger A, bionic ridger C, bionic ridger B. As the speed increased, the soil resistance increased as well. The least resistance was 0.1558KN, and was for bionic ridger C at speed of 1km/h. The maximum resistance was 0.2378KN, and was for bionic ridger E at speed of 4.2 km/h. The highest average resistance reduction ratiowas for ridger B, which had 13.66%, and for bionic ridgers A and C, the ratio was 7.46%,9.73% respectively. Bionic ridgers D and E actually had increased resistance. For once, the highest resistance reduction ratio was for bionic ridger B at speed of 4.2 km/h, and resistance reduction of 16.67%.The Finite Element Method was used for analysis and comparison of the most effective bionic ridger B during indoor experiment and the ordinary one. CATIA was used for modelling the bionic ridger, ordinary ridger and the soil and *.model format was used for transferring the model to ANSYS software for the Finite Element Model. For the soil deformation behavior, the Drucker-Prager(DP)model was used, and the surface to surface contact was used for the interaction between the ridger and the soil. After giving a displacement (Uz=10), the equivalent stress for bionic ridger was smallest ranging from 0.42~1.26MP and the maximum was 3.78MP. The equivalent stress for bionic ridger was maximum ranging from 0.42~1.26MP and the maximum was 4.12MP. The stress reduction percentage for the bionic ridger was 7.2% compared to the ordinary ridger. The stress behavior for both ridgers was almost similar, and concentrated at the front part and the two sides, only that for the bionic ridger the stress on two sides of the ridger was close an this results in low soil resistance. The plane element and curve elements used for the ordinary ridger and the bionic ridger had influence on the accuracy of the results.After that a field experiment was done for research on combined rototilling-tillage machine topic. The experiment was meant to validate the resistance reduction effect of the bionic plough, therefore a contrast experiment was done comparing the new machine and the original one, and the ordinary ridger tine and the bionic ridger tine B were used with two tractors in series providing the traction power. For the original coupling method, the soil resistances for bionic ridger compared to ordinary ridger were 16.45N,21.04N and the resistance reduction were 5.89%,7.28% with an average of 6.58%. For the new coupling method, the soil resistances for bionic ridger compared to ordinary ridger were 17.21N, 26.85N and the resistance reduction were 6.35%,9.51% with an average of 7.93%. Overally, the bionic ridger could reduce resistance by 6.91%, proving that bionic ridger was effective in reducing resistance. |
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