山核桃破壳裂纹试验与仿真分析

摘要/Abstract

摘要： 通过实验和仿真研究的方法，研究山核桃在冲击力下裂纹产生和发展的规律。用万能力学试验机进行冲击破壳试验，分别对山核桃在长轴、斜向和短轴加载方向各进行三种不同高度的15次重复试验。结果表明，无论加载方向如何，破壳冲击力的最大值都在240N左右，且越靠近横轴方向力越小，越靠近长轴方向力越大。以此为依据，将山核桃横向截面简化为圆形，通过在传统弹塑性元素接触模型基础上增加强结合力的方法，构建压头-山核桃离散单元模型。仿真结果显示，水平压头会造成山核桃模型对称裂纹形式被压溃；与此同时，竖直状态压头会以S型裂纹形式分裂山核桃模型。通过高速摄像机拍摄山核桃破壳裂纹产生过程，与仿真结果基本一致。该研究为山核桃破壳机械的设计、优化与深入地理解山核桃裂纹产生与发展机理提供了重要的参考。

关键词: 山核桃, 破壳试验, 离散单元法, 裂纹研究

Abstract: Using experimental and simulation studies, the laws of crack generation and development in hickory under impact are investigated. The experiment was mainly to use the omnipotent testing machine to carry out the impact shell breaking test and conduct 15 repeated tests for three different heights on the nut in the long axis, oblique direction, and short-axis loading direction respectively. The test results show that, regardless of the loading direction, the maximum value of the shell breaking impact force is around 240 Newtons. The force is smaller as it gets closer to the horizontal axis and larger as it approaches the long axis. Taking this as a starting point, the lateral cross-section of the nut is simplified to a circular shape, and the hickory discrete element model is constructed by adding a strong binding force model based on the conventional elastoplastic element contact model. Simulation results show that the horizontal indenter pressed at a constant speed could caused the symmetry crack of the hickory model; at the same time, the vertical indenter could cracked the hickory model in the form of S-shaped blocks. The process of hickory nut cracking was captured using a high-speed camera, which is consistent with the simulation results.This study provides an important reference for the design, optimization and in-depth understanding of the mechanism of the Chinese hickory cracking machinery.

Key words: Hickory nut, Shell breaking test, Discrete Element Method, Crack research.

中图分类号:

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曹成茂, 葛俊, 孙燕, 安敏慧, 吴敏. 山核桃破壳裂纹试验与仿真分析[J]. 中国农机化学报.

Cao Chengmao, Ge Jun, SunYan, An Minhui, Wu Min. Experimental and simulation analysis on cracking of walnut shells[J]. Journal of Chinese Agricultural Mechanization.

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