摘要
为了探明不同含水率谷子籽粒的物理机械性质,减少谷子籽粒在播种、碾米加工及储运等过程中受到压缩载荷及摩擦而产生的机械损伤,该文针对不同含水率的谷子籽粒进行压缩力学性质与摩擦特性试验。研究了谷子籽粒的挤压破碎过程,获得不同含水率谷子籽粒的力—位移(变形)曲线,破坏力、变形量及破坏能。随着含水率升高,破坏力减小,变形量和破坏能呈现先降低后升高的变化规律。同时采用赫兹接触理论,得到谷子籽粒单向表观弹性模量和许用挤压应力,结果表明二者都随含水率升高线性降低。分别测定了谷子籽粒与钢板和铝板间的滑动摩擦系数,随含水率升高,谷子与该2种材料的摩擦系数均增大,且与铝板的摩擦系数要高于钢板。根据试验结果,分别拟合得到了压缩和摩擦力学性能指标与谷子含水率的关系方程,为谷子播种、仓储、加工等装备设计及参数优化提供了基础依据。
As the first grain of“five cereals”, millet is one of the favorite grain crops and has high nutritional value and high market demand. Millet grains can be mechanically damaged under compressive load and friction in the processes of seeding, threshing, storage, and transportation. Moisture content plays an important role to mechanical properties and frictional characteristics of millet grain. The previous researches on grains’ mechanical properties were mostly about big grain kernels, but small grain kernels like millet grain have been rarely studied. In this research, a typical millet grain in Shanxi Province, Jingu-21, was selected as test material. Compression tests were carried out using a texture analyzer. Millet grains were quasi-statically loaded in vertical orientation with 7 moisture content treatments i.e. 11.4%, 12.7%, 14.2%, 17.1%, 18.7%, 21.4%and 23.7%and 25 replicates per treatment. Compression mechanical properties of millet grain were measured in terms of damage force, deformation, and damage energy, and meanwhile elastic modulus and allowable compressive stress were calculated according to Hertz theory. The damage process was analyzed, and the force-deformation curve and the variations of mechanical properties with the moisture content were obtained. The test results showed that the moisture content had a significant effect on the compression mechanical properties. The force required for initiating grain rupture decreased from 19.457 to 11.732 N as the moisture content increased, and changed slowly when moisture content was lower than 12.7%and higher than 21.4%, but decreased rapidly with moisture content increasing from 14.2% to 21.4%. Deformation and damage energy decreased initially and increased subsequently as the moisture content increased. They reached their minimums at moisture content of 17.1%and 21.4%, respectively. Elastic modulus and allowable compressive stress linearly decreased with the increase of the moisture content and the trend similar to big grain kernels was observed, w
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2015年第23期253-260,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
教育部2012年高等学校博士学科点专项科研基金联合资助课题(20121403120003)
关键词
含水率
力学特性
弹性模量
谷子籽粒
挤压应力
摩擦系数
moisture content
mechanical properties
elastic modulus
millet grain
compressive stress
coefficient of sliding friction
