谷壳破碎中微力特征的研究(英文)

Mesomechanical Characterization of in Situ Rice Grain Hulls

谷壳破碎中的微力学特性是谷物收获后加工处理设备的工程设计所首要关注的。然而,微力学特征的测算需要新的实验方法。为了研究谷壳破碎中的微力学特征,本文采用了一种结合单拉力和三点弯曲的实验方案。被抽样的谷物样本温度为27℃,并在15％的潮湿环境下,以每分钟1毫米速度的拉伸。实验结果载荷曲线表明谷壳是很容易破碎的,而且经度拉力方式甚于横度拉力方式。一般来说,经度和横度细胞的疏密造成的谷壳物质破碎对这些特性有一定的影响。谷壳的外形,表面轮廊,硅含量的增加都充分说明了谷壳结构的变化。它们之间最弱的联系是细胞层之间互锁成“S”型搭接。接点处基于稀有元素分析得出的拉力集合变化范围是5～9,而现有记录的结构变化指标估计是5～7。

Mesomechanical properties (those on a scale between micro and macro) of in situ rice grain hulls are of fundamental interest in engineering design of cereal postharvestprocessing equipment.Howerver,their measurement often requires new experimental methods. A scheme was developed combining simple tension and three-point bending tests for characterizing mesomechanical properties of in situ rice grain hulls. Sample groups were examined at 21℃,15% wet basis moisture content,and at 1 mm/min crossbar speed.The load -displacement curves indicated that the hull fracture was brittle,and it appeared to be more so in the longitudinal tension mode than in the transverse (cross) tension mode. The general materiad orthotropy in the hull due to longitudinal or transverse cellular texture had a minor effect on these properties. Structural orthotropy was manifested primarily through the overall shape, surface profile, and silicon strengthening characteristics of the rice grain hull.The weakest link is at the seam where the lemma and palea interlock into an S-shaped 'Lap-joint,'where the stress concentration factor based on finite lement analysis was from 5 to 9. The nominal structural orthotropy index (SOI) of rice grain hulls was estimated to be 5 to 7.