Analysis Of The Morphology Of Scarabaeoidea And Bionic Design Of Subsoiling Components

The morphology features of scarabaeoidea and tibiae teeth of its fore leg , their bionic applications in subsoiling components and the optimization of shape parameters of subsoiling components is the main emphasis of research in this dissertation, which is projects supported by Nationl science Fund for Distinguished Young Scholars(Grant No.50025516) and by National science Foundation of China(Grant No.50275037). The figures parameters of dung beetle was analyzed, which is the results of the lasting evolution and adaptation for environments. The teeth angles of fore-leg tibiae of the dung beetle was measured, which is radix tooth 69.3°, the first middle tooth 44.3°, the second tooth 32.1°and the apical tooth 27.5°and has a descending trend. The wedge shape of teeth top of scarabaeoidea is suited for anti-adhesion against soil thereby reducing adhesion and resistance.The contour lines of teeth and its top are measured, which can be fitted by parabolic. The parabolic shapes of teeth contour have the characteristics of digging process and reducing the cutting resistance, which offers the base on the bionics design of subsoiling components. The force of the wedge teeth of fore-leg of scarabaeoidea and soil interaction was analysed by the work theory of two-surfaces and three-surfaces wedges and apply to the forces analysis of subsoiling components cutting the soil. The results have showed the draft force is composed of three parts: the first R1 is brought by shovel edges and handle edges cutting soil, the second R2 is brought by the soil smashed and the third is the friction force between the subsoiler and soil. The draft force of subsoiler is the sum of three parts force along to the advance directions. The mathematic model of subsoiler draft force was concluded by the analysis and applied the theory of subsoiler force and the parameterized design of the bend surface of subsoiler. The subsoiler components —soil interaction is researched by the Finite Element Methods based on the Drucker –Prager elastic—plastic soil construction relationship model. The shape parameters of subsoiler component was established by the parabolic shape of the teeth contour lines of scarabaeoidea fore-leg tibiae. The inter-contour lines of the subsoiler components is the parabolic shape and selects the three sections (A-A,B-B and C-C) to determine the subsoiler shapes. The subsoiler surface was optimised by the parameters L1,L2,L5 and L6. The parabolic shapes was adopted in the subsoiler tip and the digging angleαwas determined by the angle A1, A2. The parameterized program of subsoiler components was established by the Vc programmer combining the ANSYS finite element program and realized the parameterized analysis of subsoiler. The draft force of subsoiler component can be calculated by inputting the soil parameters (elastic module, poission's ratio, soil cohesion and angle of internal friction in soil et. al ), subsoiler materials parameters and the friction coefficients between the subsoiler and soil. The stress status of the soil and subsoiler can also be showed by the ANSYS program. The design method of bionic subsoiler is summarized based on the above research wherein subsoiler of different digging angles shapes are designed. The draft force of subsoilers was tested by orthogonally experimental design in field. The results shows that the best digging angles is 27.50 consistent with the apical tooth angle of fore-leg tibiae of scarabaeiodea. The comparative results between the actual test draft force and the calculated force value of parameterized program shows the test value is comparable to the calculated value and has only 0.9% error. It shows the parameterized program can be calculated the draft force of subsoiler and also optimize the shapes parameters of subsoiler components.