基于离散元的黑木耳菌棒刺孔与摆场下落过程分析与试验

    Analysis and test of black fungus stick piercing and laying falling process based on discrete element

    • 摘要: 针对黑木耳菌棒在刺孔和摆场作业时内部菌料运动难以观测的问题,同时为实现准确模拟菌料受载情况和运动规律,该研究基于离散元法对菌棒内不同尺寸菌料的本征参数与接触参数进行标定,通过测定菌料参数,基于堆积角最优参数组合。进行菌棒刺孔仿真与实验,仿真与试验结果的孔深相对误差和孔径相对误差分别为3.6%和4.5%,验证了仿真的有效性。为了评估落地冲击对菌棒出耳孔变形的影响,模拟半自动摆场机工作时菌棒下落的过程,得到相较于顶端出耳孔,底端出耳孔孔径和孔深分别减小12.3%和14.3%,表明落地冲击使菌棒不同高度部位出耳孔变形呈现出自下而上逐渐减弱,底端出耳孔的变形最大,避免从较高处投放菌棒以减少对出耳孔的影响。仿真得到孔径和孔深最小值分别为3.2和32.5 mm,满足发耳要求,验证了摆场机能够满足农业生产中的实际需求。

       

      Abstract: This study aims to observe and simulate the internal movement of fungal material substrate during the piercing and laying of black fungal sticks using the discrete element method (DEM). The contact parameters of fungi were calibrated on the different sizes within the cultivation sticks. Key parameters, such as particle stiffness, friction coefficients, and damping factors, were adjusted to replicate the interactions among fungal particles. DEM simulations were used to accurately reflect real-world mechanical behavior. Both physical experiments and DEM simulations were conducted on piercing after calibration. The physical experiments were conducted to measure the key substrate parameters, particularly for the influences of repose angle on the substrate settles. The DEM simulations were fine-tuned to closely match the real-life scenarios after measurements. In simulations, virtual tools were inserted into the modeled fungal sticks, in order to observe substrate behavior under controlled conditions. The comparison was performed on the depth and diameter of the holes created during piercing, in order to validate the accuracy of the DEM model. The simulation results were compared with experimental data obtained from a fully automatic piercing machine. The relative errors between the simulation and experimental data were 3.6% for the hole depth and 4.5% for the hole diameter. The low error margins confirmed that the high accuracy of the model was achieved to replicate the real-world conditions, providing for the reliability of the DEM model in the subsequent simulations. In addition to the piercing simulations, a systematic investigation was also made to explore the impact of landing shock on the deformation of fruiting holes within the fungal sticks. The falling behavior of fungal sticks was simulated in a semi-automatic laying machine. Displacement velocities of substrate particles around the ear holes were measured at three positions along the fungal stick: the top, middle, and bottom. The velocities were recorded as 441, 621, and 1 115 mm/s, respectively. There was the most significant deformation at the bottom of the stick and then decreased towards the top. The diameter and depth of the bottom ear holes were 12.3% and 14.3% smaller, respectively, compared with the top ones. The minimum aperture diameter and depth were 3.2 and 32.5 mm after simulation, respectively, fully meeting the requirements for ear production. Therefore, the fungal sticks remained suitable for agricultural use, even after deformation under landing shock. The semi-automatic laying machine was effective with the acceptable deformation for practical agricultural production. In conclusion, the DEM model was validated to accurately simulate the piercing and laying in the internal movement of fungal material within black fungal sticks. The insights were gained on the deformation caused by landing shock. The findings can greatly contribute to the design and operation of machinery in mushroom cultivation. The quality and functionality of fungal sticks were maintained throughout the production. The DEM model can be expected to improve agricultural practices in mushroom cultivation.

       

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