大豆籽粒形状和尺寸分析及其建模

Shape and size analysis of soybean kernel and modeling

为建立大豆籽粒的离散元法分析模型,对大豆籽粒的几何形状和尺寸参数进行了测试分析。由测试分析可知,大豆籽粒的几何形状与椭球近似,三轴尺寸均服从正态分布,三轴尺寸中主尺寸与次尺寸间存在一定的函数关系。在此基础上,提出一种基于球充填的大豆籽粒建模方法,即将大豆籽粒的几何形状简化成椭球形,以实际大豆籽粒的各三轴尺寸平均值作为椭球的三轴尺寸,采用球充填方法建立椭球(单个籽粒)的分析模型;选单个籽粒分析模型的主尺寸,按正态分布随机生成,次尺寸通过与主尺寸的关系计算得出,由此建立具有不同尺寸及分布的大豆籽粒群体模型。以2个品种大豆籽粒为例,通过堆积试验和本文提出的"自流筛分"试验的仿真与试验结果对比可知,当充填球数为5时,仿真结果与试验结果较接近,初步证明了本文提出的大豆籽粒建模方法的可行性和有效性。

In order to build the analytic model of soybean kernel using Discrete Element Method（DEM）,the shape and size of soybean kernel are measured and analyzed.It is found that the shape of a soybean kernel can be approximated to an ellipsoid.The three axis dimensions follow normal distribution,and there exists a certain correlation between the primary dimension and the secondary dimension.On this basis,a soybean kernel modeling method is proposed based on the sphere filling.The shape of the soybean kernel is approximated to an ellipsoid,and the three axis dimensions are determined as the mean values of measured soybean kernels.The primary dimension of the analytical model of a kernel,which follows normal distribution,is randomly generated,and the secondary dimension of the kernel is calculated according to the relationship between the primary and secondary dimensions.As a result,the assemble model of the soybean kernels with different size and distribution is built.Two varieties of soybean kernels are selected as the research objects.By comparison between the simulated results and the experimental results of the packing test and the self-flowing screening test proposed in this work,it is shown that,when the amount of filling-spheres is five,the simulation results are in good agreement with the experiment results,thus,preliminarily verifying the effectiveness and feasibility of proposed modeling method.