Bionic Design Of Rotary Blade Based On Rabbit’s Claw-toe Structural Characteristics

Soil tillage combined machinery is widely used in the field of agricultural engineering because of it’s advantages of high efficiency,low consumption and fewer times of land entry.The rotary blade is an important part of the soil tillage combined machinery.The problems of soil adhesion and stalk winding always occur on it in the process of working.These problems will lead to the increase of working resistance and the decrease of tool life.In order to reduce the working resistance,the structure of rotary blade was optimized.Therefore,it is of great practical significance to improve the reliability of soil tillage combined machinery,soil constitution and the working life of rotary blade.Using the Angolan rabbit’s claw toe as the biological prototype,the bionic design of type IT245 rotary blade was studied.The paw toe model was reconstructed and its structure was analyzed.The characteristic curve was extracted to design bionic rotary blade.The operation of national standard rotary blade and bionic rotary blade in soil was simulated by using finite element software.Through comparative to analysis whether the bionic rotary blade achieves the purpose of reducing the working resistance or not.The main research contents are summarized as follows:Firstly,the paw toe is fixed with viscous material.Then the three-dimensional data of rabbit’s paw toes were obtained using a three-dimensional laser scanner.The claw toe surfaces are reconstructed by intersecting lines and point cloud fitting respectively in CATIA software.The normal distance,Gauss curvature and zebra line of the surface are analyzed.The results show that the maximum error between the surface constructed by intersecting lines and the original point cloud is 0.254 mm,which is better than the 0.341 mm surface fitted by point cloud.At the same time,it is found that the front profile of the toe and the back ridge of the toe have special structures.They can be used in rotary blade’s design.Through the N polynomial to fit the curve equation,and there correlation coefficients are above 0.996.Then,construct the three-dimensional model of the national standard rotary blade according to the size data of the national standard in the CATIA software.Using the back ridge of claw toe to replace the side cutting edge curve of national standard rotary blade,and the front profile of claw toe is made into serrated blade.At last construct three-dimensional model of bionic rotary blade.Finally,the national standard rotary blade-soil finite element model and bionic rotary blade-soil finite element model are established in Hyper Mesh software.Through the LS-DYNA solver to calculate the contact process of cutter and the soil.The results show that the rotary blade cuts from the starting point of the side cutting edge to the direction of the forward cutting edge,and the stress gradually decreases.The stress in the hole of rotary blade is always at a relatively high level,prone to the phenomenon of stress concentration.The stress on the forward cutting edge is always the smallest on the rotary blade.Compared with the national standard rotary blade,the maximum resistance of bionic rotary blade is reduced by 58 N,and The drag reduction rate is 17.8%.The maximum torque of the rotary blade is also reduced by 44.9 Nm.