颗粒饲料破损离散元仿真参数标定

Parameters Calibration of Discrete Element Simulation for Pellet Feed Attrition

为了探究气力输送中颗粒饲料的破损机理,针对当前缺乏颗粒饲料准确破损仿真模型的问题,利用EDEM仿真软件进行颗粒饲料破损离散元仿真参数标定研究。以粒径为2.50 mm混养成鱼颗粒饲料为研究对象,通过基础试验测定了颗粒饲料本征参数;通过颗粒饲料休止角试验、碰撞恢复系数标定试验和落料时间,结合试验优化设计方法,确定了饲料间的碰撞恢复系数、静摩擦因数、滚动摩擦因数为0.58、0.23、0.12,饲料和软塑料(软PVC)间的碰撞恢复系数、静摩擦因数、滚动摩擦因数为0.69、0.22、0.18;通过颗粒饲料单轴压缩破碎试验和仿真试验,结合响应面优化确定了单位面积法向刚度、单位面积切向刚度、临界法向应力、临界切向应力,分别为2.25×10^(9) N/m^(3)、8.05×10^(8) N/m^(3)、455 MPa、305 MPa。以确定的参数进行休止角仿真试验、单轴压缩仿真试验,结果表明,休止角、破碎力、落料时间的仿真值与实测值相对误差分别为0.35%、1.43%、2.81%;通过自由落料、斜面滑动、斜面滚动试验对粘结模型接触参数进行验证,结果表明,粘结模型接触参数设置合理。

The discrete element simulation parameters calibration of pellet feed attrition was carried out by using EDEM simulation software,aiming at the lack of accurate attrition simulation model of pellet feed,so as to explore the damage mechanism of pellet feed in pneumatic conveying.The intrinsic parameters of pellet feed with a particle size of 2.50 mm,which was used as the object and served for polyculture adult fish,were determined through basic experiments.The coefficient of restitution,coefficient of static friction and coefficient of rolling friction between feeds were determined to be 0.58,0.23 and 0.12,respectively,while these three coefficients between feeds and soft plastics(soft PVC,polyvinyl chloride)were 0.69,0.22 and 0.18,respectively through AoR(angle of repose)test of pellet feed,coefficient of restitution calibration test and discharge time of pellet feed,combined with the experimental optimization design method.The normal stiffness per unit area,shear stiffness per unit area,critical normal stress and critical shear stress were determined by uniaxial compression breakage test and simulation test of pellet feed,combined with response surface optimization,which were 2.25×10^(9) N/m^(3),8.05×10^(8) N/m^(3),455 MPa and 305 MPa,respectively.The AoR simulation test and uniaxial compression simulation test were conducted with the determined parameters,whose results showed that the relative errors between the simulated value and the measured value in AoR,breakage force and discharge time were 0.35%,1.43%and 2.81%,respectively;the contact parameters of the bonding model were verified by tests of free discharge,inclined sliding and inclined rolling,whose results showed that the contact parameters of the bonding model were reasonably set.The model developed could provide a method and theoretical basis for the calibration of discrete element simulation parameters and the study of attrition mechanism of pellet feed.