基于Tavares模型的多面体棉籽离散元参数标定与试验

Parameter Calibration and Experiment of Polyhedral Cottonseed Discrete Element Based on Tavares Model

摘要:

针对基于离散元法的棉籽压缩破碎过程中缺少准确仿真模型的问题，本文以新陆早84号棉籽为研究对象，结合物理试验与仿真试验，对棉籽参数进行标定。基于三维扫描技术，使用Solidworks 2022中的网格建模功能，快速建立棉籽多面体模型。采用堆积角试验对棉籽种间参数进行标定，得到棉籽-棉籽碰撞恢复系数、棉籽-棉籽静摩擦因数、棉籽-棉籽滚动摩擦因数的最优参数组合为0.106、0.248、0.105，仿真堆积角与实际堆积角相对误差为0.28%，证明棉籽种间参数准确。通过单颗粒压缩试验对Tavares模型参数进行标定，以棉籽破碎力与破碎能为指标进行验证，结果表明棉籽破碎力与破碎能相对误差分别为2.37%和2.87%，说明构建的棉籽模型和Tavares模型参数可以表征棉籽压缩破碎过程。

Abstract:

Aiming to address the lack of an accurate simulation model for the compression and crushing process of cottonseed, based on the discrete element method, the Xinluzao 84 cottonseed was used as the research object, and its parameters were calibrated through the combination of physical tests and simulations. According to the actual morphological characteristics of cottonseed, the volume of cottonseed was calculated by using the average particle size to represent the size of cottonseed in the vertical length direction, and the result was less error with the volume obtained by using the triaxial dimensions, which proved that it was reliable to use the average particle size to describe the size of cottonseed in the vertical length direction. The polyhedral model of cottonseed was rapidly constructed by using the mesh modelling function in Solidworks 2022.The correlation was established between the volume relative error, simulation time, and the number of facets of the model. It was determined that the optimal number of facets for the polyhedral cottonseed model was 1.098, with corresponding simulation time of 171 minutes and volume relative error of 0.46%. The stacking angle test was employed to calibrate the interspecific parameters of cottonseed. The results indicated that the collision recovery coefficient of cottonseed-cottonseed, the static friction coefficient of cottonseed-cottonseed, and the rolling friction coefficient of cottonseed-cottonseed had a significant effect on the stacking angle. The optimal parameter combinations were determined to be 0.106, 0.248, and 0.105, respectively. Relative error of 0.28% was observed between the simulation stacking angle and the actual stacking angle when using these parameter values, demonstrating the accuracy of the cottonseed parameters. The parameters of the Tavares model were calibrated and verified by the indexes of cottonseed crushing force and crushing energy through the single particle compression test. The results showed that the relative errors of cottonseed crushing force and crushing energy were 2.37% and 2.87%, respectively. This indicated that the constructed cottonseed model and the calibrated parameters of the Tavares model were able to effectively characterize the compression and crushing process of cottonseed.