基于离散元法玉米秸秆双层粘结模型力学特性研究

针对玉米秸秆外表皮与内穰力学特性存在显著差异问题,建立离散元玉米秸秆双层粘结双峰分布模型,通过力学试验与虚拟仿真试验对比,标定玉米秸秆外表皮和内穰力学参数,校正离散元模型,探究玉米秸秆力学特性.结果表明,采用离散元Hertz-Mindlin with bonding颗粒接触方法可建立玉米秸秆双层粘结双峰分布模型.完善DEM方法建立玉米秸秆颗粒粒度随机分布的双层粘结模型方法.通过力学试验得出青贮玉米秸秆外表皮弹性模量和剪切模量分别为982.52和387.58 MPa,青贮玉米秸秆内穰弹性模量和剪切模量分别为28.64和8.13 MPa,外表皮木质部与内穰纤维部力学特性差异显著.计算得出外表皮-外表皮、外表皮-内穰、内穰-内穰之间粘结参数.通过单轴压缩试验,剪切与虚拟仿真试验对比验证离散元模型可靠性.文章所建立玉米秸秆双层粘结双峰分布离散元模型表征两者力学特性差异,为青贮玉米饲料数值化研究提供理论依据.

Study on mechanical properties for corn straw of double-layer bonding model based on discrete element method

In view of the significant difference between the mechanical properties of the outer skin of corn stalk and corn stalk pith, a discrete element corn stalk double-layer bond a bimodal distribution model was established. The mechanical parameters of the outer skin of corn stalk and corn stalk pith were calibrated and the discrete element model was corrected to explore the mechanical properties of corn stalk. The results showed as the followings, based on the discrete element Hertz Mindlin with bonding particle contact model, a bimodal distribution model of double-layer bonding of corn straw was established. DEM method was supplemented to establish the double layer bond model of corn straw particle size random distribution. The elastic modulus and shear modulus of silage corn straw were982.52 MPa and 387.58 MPa, respectively, and the elastic modulus and shear modulus of silage corn straw were 28.64 MPa and 8.13 MPa, respectively. The mechanical properties of the xylem of the outer epidermis and the fiber of corn stalk pith were significantly different. The bond parameters the outer skin-outer skin, the outer skin-pith and the pith-pith were calculated. The reliability of discrete element model was verified by comparing uniaxial compression test, shear test and virtual simulation test. In this paper, the bimodal distribution model discrete element model of corn straw double-layer bonding was established to characterize the mechanical properties of corn straw skin and corn straw pith, which provided specific data and model support for the development of silage corn feed.