Calibration and Experimental Verification of Finite Element Parameters for Alfalfa Conditioning Model

Qiao Jin, Yong You, Haiyi Wang, Xueting Ma, Liang Wang, Decheng Wang () and Xianfa Fang ()
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Qiao Jin: College of Engineering, China Agricultural University, Beijing 100083, China
Yong You: College of Engineering, China Agricultural University, Beijing 100083, China
Haiyi Wang: College of Engineering, China Agricultural University, Beijing 100083, China
Xueting Ma: College of Engineering, China Agricultural University, Beijing 100083, China
Liang Wang: College of Engineering, China Agricultural University, Beijing 100083, China
Decheng Wang: College of Engineering, China Agricultural University, Beijing 100083, China
Xianfa Fang: The State Key Laboratory of Soil, Plant and Machine System Technology, Beijing 100083, China

Agriculture, 2024, vol. 14, issue 10, 1-21

Abstract: Conditioning is an important step in harvesting alfalfa hay, as squeezing and bending alfalfa stems can break down the stem fibers and accelerate the drying rate of alfalfa. The quality of alfalfa hay is directly affected by the conditioning effect. The finite element method (FEM) can quantitatively analyze the interaction relationship between alfalfa and conditioning rollers, which is of great significance for improving conditioning effects and optimizing conditioning systems. The accuracy of material engineering parameters directly affects the simulation results. Due to the small diameter and thin stem wall of alfalfa, some of its material parameters are difficult to measure or have low measurement accuracy. Based on this background, this study proposed a method for calibrating the finite element parameters of thin-walled plant stems. By conducting radial tensile, shear, bending, and radial compression tests on alfalfa stems and combining with the constitutive relationship of the material, the range of engineering parameters for the stems was preliminarily obtained. By conducting a Plackett–Burman experiment, the parameters that affect the maximum shearing force of stems were determined, including Poisson’s ratio in the isotropic plane, radial elastic modulus, and the sliding friction coefficient between the alfalfa stem and steel plate. By conducting the steepest ascent experiment and Box–Behnken experiment, the optimal values of Poisson’s ratio, radial elastic modulus, and sliding friction coefficient were obtained to be 0.42, 28.66 MPa, and 0.60, respectively. Finally, the double-shear experiment, radial compression experiment, and conditioning experiment were used to evaluate the accuracy of the parameters. The results showed that the average relative error between the maximum shear and the measured value was 0.88%, and the average relative error between the maximum radial contact force and the measured value was 2.13%. In the conditioning experiment, the load curve showed the same trend as the measured curve, and the simulation results could demonstrate the stress process and failure mode of alfalfa stems. The modeling and calibration method can effectively predict the stress and failure of alfalfa during conditioning.

Keywords: alfalfa; finite element method; parameter calibration; conditioning rollers (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2024
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