Design Of Bionic Stubble-cutting Blade Based On The Structural Characteristic Of Praying Mantis (Mantis Religiosa Linnaeus)’s Foreleg

In north China, people usually use handy soil-digging tools to remove soil fromstubbles and then burn them. This process is rather slow and not cost effective, and moreseriously, directly burning stubbles in the field pollutes the air. So it is both economicallyimportant and friendly environmental required to research, design and develop astubble-cutting tool. Base on the study of the foreleg of praying mantis, a series of bionicstubble-cutting blades were designed in this work. Finite element method and fieldmeasurement were used to examine the working performance of these bionic blades.Soil tillage has always been a research focus in agricultural engineering. As any tillageoperation is a process of cutting and breaking soil, tillage force mainly depends upon theblade shape, soil property, and operating conditions. Actually, almost allthe soil cutting toolsused in farming have been developed by field experiments and by trial and error. Accuratemodeling of soil material and soil-implement interaction is the basic key to this optimizationand may reduce the need for numerous expensive field tests. Finite element method (FEM)shows some advantages in this aspect, since any implement structure and non-linearbehavior of tillage interaction can be modeled if a proper constitutive law is chosen. In thiswork, a3D dynamic simulation model using FEM of the soil-cutting blade was establishedto predict the working effect of soil-cutting tool-blade L and to compare and analyze theeffects of different rotational speeds（220r/min，300r/min，388r/min） and rotational forms（up-cut rotation and down-cut rotation）. In order to measure the cutting force of blade L，a specialized test device was designed in an soil bin laboratory. A relatively good generalcorrelation was obtained between the finite element simulation and the experimental results.Hence, it is proven that the finite element model in this work is a general and useful tool and it would play an important role in the design and development of tillage forms and tools.As an excellent predator in insect world, the praying mantis has a pair of powerful tools,two sharp and strong forelegs, and the femur and tibia are both armed with a double row ofstrong spines along their posterior borders. They can be flexed on each other so that anyobject is firmly grasped between these spines. The shape and arrangement of these sharpspines are valuable to the bionic design of energy-saving and drag-reduction cutting tools. Inthis work, detailed investigations which can supply reference information to the bionicdesign of cutting tools based on the morphologies of the forelegs in the prayingmantis(Mantis religiosa Linnaeus) were carried out by microscopy. Moreover, a conceptionof Fuzzy Similarity was introduced, and an effective mathematical method was put forwardto identify the extent of morphology similarity between two creatures and quantitativelyanalyze the similitude degree. Besides, scanning electron microscopy was used to obtaininformation of the surface microstructure of the tibia, femur and the spines. The mechanicalproperties of these parts were investigated by nanoindenter and Vickers hardness testerrespectively. From these analysis results, it can be found that shape of the foreleg of prayingmantis highly serves the prey action，and the dense, well-aligned squamous cell and arrisfibers offer excellent mechanical properties to this powerful capture tool—tibia and femur.According to the morphologial analysis of praying mantis’s forelegs, the shape andarrangement of the spines in femur and tibia were imitated in this work. The cuttingequipments of subterranean crops (such as potatoes) harvest machines were taken as areference.The bionic design of cutting blades was conducted. Finite element model and fieldtests were conducted to analyze and compare the working performance of the bionic cuttingblades in this work. The results show that cutting edge shape has a great influence on thesoil-cutting force. The reference blade without bionic design element has more cutting forceand cutting work than the blades by bionic design. The working velocity of cutting bladeshas little influence on the cutting force and cutting work.