Cutting Mechanical Characteristics And Simulation Analysis Of Cassava Stalk

Cassava,sweet potato and potato are called the world three big potato,cassava is the fifth crops except rice,sweet potato,sugarcane and corn in south subtropical region of China.Cassava harvesting mechanization is an important link of cassava production mechanization,and cutting of cassava stalk is the primary task of mechanized harvesting of cassava.Cassava stalk cutter is the key components of cassava stalk harvester.Research on cassava stalk cutting mechanism is the basics of carrying out a variety of cassava harvester and cassava stalk crushing returning machine design,dynamic simulation,mathematical modeling,it has important theoretical and practical significance.This paper takes cassava stalk as the research object,Based on the multifunctional stem cutting test platform that agricultural machinery institute of Chinese tropical agricultural sciences academy developed,through the combination of theoretical analysis and test,it simulates the dynamic process of cassava stalk cutting by the finite element numerical simulation software,analysis of the changes force and power consumption during the process of cutting,to explore the factors of influencing cutting energy consumption,revealing the cassava stem cutting mechanism,so as to provide theory and technology support for the design of cassava stalk harvester.The main results include the following:(1)In order to main varieties 205 cassava stalk of Chinese Southern area as the research object,studied stem component and microscopic micro-structure of influencing cutting force:obtain the chemical composition of cassava stalk;proved the stem xylem structure of cassava through the infrared spectrum,X diffraction,Heavy-hot bad and differential thermal angles;through analyzing the SEM image of cassava stalk phloem,xylem and pith,clear the microscopic structure,so as to provide the basis for the characterization of cassava stalk physical mechanical properties and analysis its material properties.(2)In order to harvest cassava stalk root as the research object,experimental determination and analysis of stalk biological parameters and physical mechanical properties:measured stem diameter,phloem thickness,pith diameter,water content and bulk density and other parameters;analyzes the distribution regularity of mechanics along the stem direction;through experiments,it obtained Cassava stems breaking stress and elastic modulus in different parts of under axial tension,axial compression,radial compression,shear axial,radial shearing and radial bending.(3)Analyzing the cassava stalk heavy cutting,no leakage and cut collision conditions during cutting process;relying on the cutting test bench,having cutting test for cassava stalk of harvest period.Through the experiment,analyzing the cassava stalk the maximum cutting force changes in the blade angle,cutting angle,angle cutter,cutter speed,the machine speed and different factors level,after the optimization,the optimum combination of the cutter parameters are cutter blade angle 27.95°?cutting angle 20.52°,angle cutter 2.60°,cutter speed 500.11rpm,the machine forward speed 0.59m/s,and the maximum cutting force is minimum.(4)By using the method of combining theoretical analysis and finite element analysis,analyzing the process of compression and bending failure of cassava stalk,Combined with the physical mechanical properties parameters of cassava stalk and test process,put forward the hypothesis of cassava stalk material,and through analyzing the test results of the xylem samples,to determine that cassava stalk is the transverse isotropic material.To deduce and determine elastic mechanics characteristic parameters of cassava stalk.establishing cassava stalk digital model and simulate the mechanical deformation of cassava stalk in axial compression,lateral compression,the stress and radial bending,obtaining the displacement,stress,strain and shear stress contours of cassava stalk in failure limit state.(5)Combined with test bench testing process of the actual cutting cassava stem,having the appropriate assumptions,determining the conditions of numerical simulation,Based on the ANSYS/LS-DYNA,establishing the cassava stalk cutting system finite element model;Using the finite element model to complete the display of dynamic numerical simulation of disc cutter cutting stem,and the simulation results are analyzed in detail,by introducing artificial bulk viscosity and viscous damping hourglass control numerical results oscillation calculation,verifying the reliability and stability of the simulation results.By changing cutting parameters,having numerically simulate analysis for the dynamic process of cutter cutting stem in different situations,according to the simulation of cutting process animation,using LS-DYNA post-processing software LS-PrePost to analyze on the cutting stress size and distribution,strain size and change over time,cutting force size and change over time,cutting energy size and change over time,further studies on the mechanism of cutting stem..