| Yunnan panax notoginseng is a traditional Chinese herbal medicine, and its main roots have the most commercial value. Crushing process of main root is very necessary before edible or extraction of effective components of Panax notoginseng root. With the recent increase of market demand of panax notoginseng, the is no special crushing equipment for panax notoginseng.It Caused a lot of panax notoginseng crushing problems, including low efficiency, high energy consumption, poor quality and so on. It has been unable to meet consumer demand for high quality of panax notoginseng.Meanwhile there is no report about mechanical characteristics of panax notoginseng of main root. However, it is very important for the design, dynamic simulation and mathematical modeling of shredder of panax notoginseng to research the mechanical properties of their main roots.The main root of panax notoginseng components from center xylem and outer skin.Their structures are obviously different. In this work, elastic mechanical properties, stress relaxation and creep of main root were tested through texture analyzer. The main root was abstracted as a cylinder model, and were obtained the basic physical parameters and mechanical parameters of main root model. Through finite element software simulation,the main root and the blade grinding process were simulated, and the stress and strain nephogram of the main root and blade collision in different velocity were obtained. The main research results are as follows:(1)The average values of radial compression strength, axial compression strength, axial shear strength, radial shear strength, axial elastic modulus, radial elastic modulus, axial shear modulus and radial shear modulus of center xylem were 21.07,27.80,9.58,7.06,93.46,192.59, 44.68,50.69 MPa respectively, and the average values of radial compression strength, axial compression strength, axial shear strength, radial shear strength, axial elastic modulus, radial elastic modulus, axial shear modulus and radial shear modulus of outer skin were 20.27,17.87, 9.08,9.19,246.48,113.51,20.84,74.84MPa respectively. The axial and radial poisson ratio of center xylem were 0.08 and 0.05. The axial and radial poisson ratio of outer skin were 0.12 and 0.04.(2)Getting the axial and radial stress relaxation curve of main root, and the stress relaxation model is Generalized Maxwell model with spring. The axial stress relaxation mathematical model of main root is σ= 0.49e-t/268-23+0.57e-t/15.16+5.7. We obtained the radial stress relaxation curve and model parameters in 0.04,0.05,0.06,0.07 constant strain. The results can be seen from the strain in 0.05～0.07, the sample has the obvious stress relaxation, stress decrease continuously with the lapse of time, attenuation to tend to balance in the balance. But the stress relaxation phenomenon is not obvious in 0.04 strain. Balance coefficient of elasticity and two elastic coefficient of the decay increases with the increase of strain, relaxation time of Ti, T2 not affected by strain.(3)The main root axial creep model in 2400N force is the four element Burgers model, which of the mathematical expression is The main root axial creep model in 400N force is the three element Kelvin model, which of the mathematical expression is D(t)=2.35+2.56 x (1-e59.50). Besides this, also analyzes the influence of the load on the axial creep characteristics of the main root. The instantaneous elastic modulus Ee, delayed elastic modulus Ei and viscosity coefficient η1 are decreased with increasing the load F. The change range of Ei is small, and the change range of E1 and η1 are larger.(4) Analysis stress of cutter fillet how to affect the collision between square section cutter and main root by ANSYS to get the maximum stress and strain of cutter and main root in the collision speed of 20m/s,40m/s,60m/s,80m/s; Analysis stress of cutters shape (Cylinder, wedge, cube) how to affect the collision between cutter and main root by ANSYS to get the maximum stress and strain of cutter and main root in different collision speed.In summary, center xylem and outer skin of Yunnan panax notoginseng main root can be considered as anisotropy material, the mechanical modeling should be treated as anisotropic material. The main root of panax notoginseng is viscoelastic material. It also has the nature of fluids and solids. Informed by stress relaxation and creep parameters:Elastic properties of radial main root increased with the increase of deformation, fluid properties of axial main root increased with the increase of force. By the finite element analysis results show that the best fillet of square section cutter is 3mm and the best cutter shape is cylinder. |
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