类芦茎秆离散元模型建立与参数标定

Establishment and Parameter Calibration of Discrete Element Model for Neyraudia reynaudiana Stalk

摘要:

针对类芦缺少切割粉碎仿真模型，以类芦为研究对象，建立茎秆的离散元模型并完成具体参数测定与标定。首先，搭建测试平台，测定了类芦茎秆与钢的碰撞恢复系数、静摩擦因数与滚动摩擦因数等接触参数，建立了类芦茎秆模型并开展仿真堆积角试验，根据Box-Behnken试验方案以及物理堆积角（23.47°），标定了茎秆间接触参数。其次，开展物理剪切与压缩试验，得到茎秆最大剪切力Fd=155.18N，最大压缩破坏力Fc=844.36N；为进一步建立柔性类芦茎秆模型，选取Hertz-Mindlin with Bonding为颗粒间粘结模型，通过Central Composite试验方案开展该模型的仿真剪切、压缩试验，以Fd与Fc为优化目标，完成粘结模型参数标定。得到类芦茎秆离散元模型参数：茎秆间的碰撞恢复系数、静摩擦因数和动摩擦因数分别为0.35、0.60和0.0049；粘结模型中单位面积法向和切向刚度分别为6.13×1010N/m3和3.96×1010N/m3，法向应力和切向应力分别为3.5×107Pa和4.0×107Pa。开展仿真验证试验，物理与仿真试验结果最大偏差为4.81%，表明所建立的类芦茎秆离散元模型较为合理，研究结果可为类芦剪切粉碎装置的设计提供理论基础。

Abstract:

Aiming to address the lack of simulation models for cutting and crushing Neyraudia reynaudiana stalk, a discrete element model for Neyraudia reynaudiana stalk was established and the determination and calibration of specific parameters were completed. Firstly, a test platform was set up to determine contact parameters such as collision recovery coefficient, static friction, and rolling friction coefficient between the Neyraudia reynaudiana stalk and the steel plate. A Neyraudia reynaudiana stalk model was established, and a simulation stacking angle test was conducted. The contact parameters between stalks were calibrated by using the Box-Behnken test scheme and physical stacking angle (23.47°). Secondly, physical shear and compression tests were conducted to obtain the maximum shear force of the stem: Fd=155.18N, and the maximum compressive failure force: Fc=844.36N. To further establish the flexible Neyraudia reynaudiana stalk model, the Hertz-Mindlin with Bonding was selected as the inter-particle bonding model parameter. Simulation shear and compression tests of the model were carried out by using the Central Composite test program, and the bonding model parameter was calibrated with Fd and Fc as optimization targets. The parameters of the discrete element model for Neyraudia reynaudiana stalk were obtained as follows: collision recovery coefficients, static rubbing coefficients, and dynamic friction coefficients of the stalks were 0.35, 0.60, and 0.0049;the normal and tangential stiffnesses in the bonding model of the flexible Neyraudia reynaudiana stalk model were 6.13×1010N/m3 and 3.96×1010N/m3, respectively, and the normal and tangential stresses were 3.5×107Pa and 4.0×107Pa, respectively. The simulation validation test showed a maximum deviation of 4.81% between the physical and simulation test results, indicating that the discrete Neyraudia reynaudiana stalk model was more reasonable. Overall, the research result can provide a theoretical basis for the design of subsequent shear crushing devices for Neyraudia reynaudiana stalk.