糙米腹背部破碎特性与裂纹扩展研究

Study on crushing characteristics and crack propagation of brown rice ventral and dorsal side

研究糙米碾白过程中腹部、背部的破碎特性。利用万能材料试验机进行力学试验,通过数字显微镜观察糙米中裂纹及其扩展变化。结果表明:糙米背部的结构组织强度大于腹部;在三点弯曲和剪切载荷下,裂纹总是从糙米籽粒底部的支撑面产生,并向上扩展至载荷作用面,糙米腹部、背部抗剪切变形能力低于抗弯曲变形能力,当碾白压力大于30 N,大量的糙米会产生裂纹,在碾白过程中,要考虑将碾白压力控制在30 N以下。研究确定了糙米腹背部组织结构的差异性,可为碾米机的设计和碾米加工工艺提供参考。

The crushing characteristics of the ventral and dorsal side of brown rice during milling were studied.The mechanical test was carried out by universal material testing machine,and the crack and its propagation in brown rice were observed by digital microscope.The results showed that the structural strength of the dorsal side of brown rice was greater than that of the ventral side.Under three-point bending and shear loads,cracks always occured from the supporting surface at the bottom of the brown rice grain and extended upward to the load action surface.The shear deformation resistance of the ventral and dorsal side of the brown rice was lower than that of the bending deformation resistance.When the whitening pressure was greater than 30 N,a large amount of brown rice would crack.In the process of whitening,it was necessary to consider controlling the whitening pressure below 30 N.The study determined the difference of the tissue structure of the ventral and dorsal side of brown rice,which could provide a reference for the design of rice milling machine and rice milling processing technology.