Determining the collision properties of semi-crystalline and amorphous thermoplastics for DEM simulations of solids transport in an extruder
Determining the collision properties of semi-crystalline and amorphous thermoplastics for DEM simulations of solids transport in an extruder
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DOI：
10.1016/j.ces.2007.03.033
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发表时间：
2007-07-01
影响因子：
4.7
通讯作者：
Thompson, M. R.
中科院分区：
文献类型：
--
作者：
Moysey, P. A.;Thompson, M. R.
为了改进离散单元法(DEM)在聚合物加工应用中的应用，有必要对一些常用聚合物的接触力学进行评估。通过不同入射角度和不同冲击速度下球形聚合物粒子与钢砧座的碰撞实验，揭示了高密度聚乙烯(HDPE)、聚苯乙烯(PS)和聚碳酸酯(PC)的接触行为。恢复系数和摩擦系数是通过对个别碰撞的高速视频分析计算出来的。收集的数据被用来评估几个流行的法向接触力-位移模型的相关性，以确定它们对测试的半结晶和玻璃聚合物的适用性。所考虑的模型是沃尔顿和布劳恩[1986]提出的模型。非弹性摩擦圆盘剪切组件的粘度、颗粒温度和应力计算。流变学杂志30,949-980]，具有恒定(WBCE)和可变(WBVE)正常恢复系数，和桑顿[1997]。弹性-理想塑性球体共线碰撞的恢复系数。应用力学学报，，基于弹塑性碰撞理论。将碰撞数据与不同接触力-位移模型的DEM模拟结果进行比较，发现WBVE模型与HDPE的粘弹-全塑性行为具有最好的整体一致性，而PC和PS的几乎纯弹性性质与本文研究的所有三种模型都很好地吻合。根据冲击研究的结果，讨论了法向力-位移模型对挤出机固体传输区的影响。(C)2007爱思唯尔有限公司。保留所有权利。
To improve application of the distinct element method (DEM) to polymer processing applications it was necessary to evaluate the contact mechanics of a selection of commonly used polymers. The contact behaviors of high-density polyethylene (HDPE), polystyrene (PS) and polycarbonate (PC) were revealed in this paper from a series of impact studies where spherical polymeric particles struck a steel anvil at various angles of incidence and impact velocity. The coefficients of restitution and friction were calculated from high-speed video analysis of individual impacts. The collected data was used to evaluate the relevance of several popular normal contact force-displacement models to determine their suitability for the tested semi-crystalline and glassy polymers. The models considered were those proposed by Walton and Braun [1986. Viscosity, granular-temperature, and stress calculations for shearing assemblies of inelastic, frictional disks. Journal of Rheology 30, 949-980], with constant (WBCE) and variable (WBVE) normal restitution coefficient, and Thornton [1997. Coefficient of restitution for collinear collisions of elastic-perfectly plastic spheres. Journal of Applied Mechanics 64, 383-386], based on elastic-plastic collisions. Comparison of the impact data with DEM simulations using the various contact force-displacement models revealed that the WBVE model provides the best overall agreement with the viscoelastic-fully plastic behavior of HDPE, while the almost purely elastic nature of PC and PS agreed well with all three models studied in this paper. The influence of the normal force-displacement models on the solids transport zone of an extruder was subsequently discussed based on the findings from the impact study. (c) 2007 Elsevier Ltd. All rights reserved.