CAJ | 학술논문

为了准确预测颗粒物料的堆积角，研究采用数值仿真方法对堆积状态的颗粒物料进行模拟预测。以稻谷颗粒物料为例，应用离散元法和 MATLAB 图形图像处理技术，模拟了稻谷在无底圆筒中落料堆积现象，并对堆积图像轮廓采取线性拟合，在非试验条件下预测出稻谷堆积角，预测堆积角为22.66°±0.49°，与实际堆积试验比较，试验堆积角为22.62°±0.33°，误差为0.18%。结果表明：数值模拟结合图像特征提取的方法对稻谷颗粒物料堆积角的测量有较好的适用性，能实现对已知物理及力学参数的椭球形颗粒物料堆积角的预测，研究的结果可为农业散体非规则形籽粒堆积角的数值测量提供参考。
위료준학예측과립물료적퇴적각，연구채용수치방진방법대퇴적상태적과립물료진행모의예측。이도곡과립물료위례，응용리산원법화 MATLAB 도형도상처리기술，모의료도곡재무저원통중락료퇴적현상，병대퇴적도상륜곽채취선성의합，재비시험조건하예측출도곡퇴적각，예측퇴적각위22.66°±0.49°，여실제퇴적시험비교，시험퇴적각위22.62°±0.33°，오차위0.18%。결과표명：수치모의결합도상특정제취적방법대도곡과립물료퇴적각적측량유교호적괄용성，능실현대이지물리급역학삼수적타구형과립물료퇴적각적예측，연구적결과가위농업산체비규칙형자립퇴적각적수치측량제공삼고。
Angle of repose is an important macroscopic feature in characterising the interactions within an assembly of particles. In order to accurately predict the angle of repose of the particle material,a numerical simulation study was applied on the process of particle packing based on discrete element method. In this paper, a simulation model of bottomless cylinder was designed with EDEM software. By taking the rice particles as the example, the physical properties of rice particles, including density, Poisson’s rate, shear modulus, coefficient of restitution, coefficient of static fraction, and coefficient of rolling fraction were obtained through the study of some scholars. The shape of rice particle was regarded as ellipsoid. The average value of rice particles’ dimension parameters were reported in statistics, namely the long axis is 7.2 mm, and the minor axis is 3.0 mm. According to the shape and the dimension parameters of rice particles, a method for establishing the model of particle based on particles agglomerate was employed, and with the 9 spherical particles agglomerate to approximate real shape grain. In the process of simulation, the cylinder was firstly filled with rice particles. Based on the number and density of particles, the average mass of 43.12 g was calcuated. After being filled with the particles, the cylinder was slowly lifted at a speed of 0.05m/s. Particles flowed from the mouth of the cylinder and formed a stable accumulation under gravity load. In addition, this paper analysed the influence of different lifting speed on the accumulation form.The numerical results showed that, under identical conditions, increasing lifting speed of cylinder led to the rise in diffusion trend of the edge of the grain heap particles. However, when the speed was less than 0.07 m/s, granular pile was formed relatively stably. Meanwhile, this paper obtained the unilateral outline of particle accumulation through MATLAB image processing technology. Then linear fitting was applied to process image contour of rice packing and the angle of repose of rice was predicted in a non-experimental condition. In the end, the discrete element method combined with image processing technology showed that the angle of repose of rice was 22.66°±0.49°. The accumulation of rice particles was verified in the test trial. Under the same condition with simulation, field test result showed the angle of repose of rice was 22.62°±0.33°. In comparison with the simulation result, the error of the repose angle of rice from field test was 0.18%. Therefore, discrete element method and matlab image processing technology could be applied to simulate rice packing in the bottomless cylinder. The result showed that the method which combines the numerical simulation with feature extraction from image has good adaptability for measuring the angle of repose of particle material and can achieve the prediction of the repose angle of particle material on known physico-mechanical parameters.With the improvement of computer tecnology and algorithms, for agricultural particulate materials,the prediction method would bring guidance for the numerical determination of the angle of repose, the study of friction and mobility characteristics and the design of related storage and processing equipments.