Mechanical Modeling And Analysis Of Finite Element Method For Ramie Stalk

Ramie stalk is composed of bast fibre and xylem mainly. With the increasing demandsof bast fibre on market, making Bast fibre and xylem Ramie stalk peel off is very focalpoint of research. In order to reach the purpose, we must understand intensively themechanical properties and differences of ramie stalk, bast fibre and xylem. By theadvanced test equipment, their mechanical parameters are tested. According to reachingtested parameters, the corresponding mechanical model is established. Hoping to findtheir changeable form of stress and strain and get some theoretical guides in designresearch.Research on agriculture material mechanical properties is more difficult by theoreticalanalysis and compute method fully. According to the understanding of inland and overseadocuments on material characteristics and mechanical properties, research on theirmechanical properties and their change of stress and strain under different loads areemphasized. Supposing that ramie stalk is made up of two kinds of different material(bast fibre and xylem). But their differences of mechanical properties are ignored. Itsmacroscopic behaviors are homogenous, linear elasticity and belong to transverselyisotropic constitutive relation. In the same time, in case that each of bast fibre and xylemis the same constitutive relation as ramie stalk. Based on above-mentioned analyticalhypothesis, the bending, tensile and compressive experiments were conducted for theramie stalk, bast fibre and xylem. The corresponding elastic constants were analyzed andtheir maximum, average and minmum values were obtained.On the basis of getting the average size and the average elastic constants. It isassumed that ramie stalk, bast fibre and xylem are the geometrical model of hollowcylinder. The stress and strain distributions of ramie stalk under the transverselyeven-distributed load are analyzed through ANSYS Software. According to thegeometrical size and the material attributes of peeling roller, building the dynamicsimulation model of roller and ramie stalk. The distribution of stress and pressure ofelements on ramie stalk are analyzed through ANSYS Software. The major research achievements are as follows:(1) Establishing transversely isotropic constitutive relation of ramie stalk, bast fibreand xylem and their analytical model of elastic theory, a series of general solutions wereobtained.After comparing the main methods in solving these equations, the finite elementmethod is the best.(2) The tensile and compressive experiments were conducted for the xylem,bastfibre and ramie stalk. The results are as follows: the averages of tensile strength of xylemare 177.26 MPa and 32.249 MPa, respectively, for bast fibre, they are 1909.08 MPa and82.51 MPa, respectively. The average of Yong's modulus of ramie stalk is 118.88MPa.Their parameters of constitutive relation are determined.(3) The law of the changeable stress distribution of xylem and bast fibre areanalyzed under four kinds of different loads. The results are as follows: When loads getlager, the maximum deformations expand from Bast fibe to xylem. When there are117.15N and 254.29N, the obvious transition stage of their deformation distribution takesplace.(4) When the transversely modulus are changed under the same load, the results areas follow: The modulus of bast fibre and xylem are the value of maximum, the maximumdeformation distribution take place on the layer of bast fibre; When their modulus areaverage, the maximum deformation area take place on contact surface;When theirmodulus are minimum, the maximum deformation area take place on the xylem.(5) The graph of maximum stress, the curve of pressure-time and the curve ofdisplacement-time on ramie stalk are taken from the LS-PREPOST of LS-DYNA. Bycomparison the results are as follows: When input velocity of ramie stalk is notchangeable, with the increasing of rotary velocity of roller, its maximum value of stress,pressure and displacement of elements get lower.When rotary velocity of roller is notchangeable, with the decreasing of input velocity of ramie stalk, Its maximum value ofstress, pressure of element is lower than the corresponding ones of high input velocity.