洪俊^1,2, 李建兴¹, 沈月¹, 王潇¹
AuthorsHTML:洪俊^1,2, 李建兴¹, 沈月¹, 王潇¹
AuthorsListE:Hong Jun^1,2, Li Jianxing¹, Shen Yue¹, Wang Xiao¹
AuthorsHTMLE:Hong Jun^1,2, Li Jianxing¹, Shen Yue¹, Wang Xiao¹
Unit:1. 东南大学土木工程学院，南京 211189；2. 东南大学江苏省工程力学分析重点实验室，南京 211189
Unit_EngLish:1. School of Civil Engineering, Southeast University, Nanjing 211189, China
2. Jiangsu Key Laboratory of Engineering Mechanics, Southeast University, Nanjing 211189, China
Abstract_Chinese:为了模拟颗粒的破碎过程, 反映颗粒破碎后碎片的真实形状, 改进了多面体的接触识别算法, 提出了一种基于离散元法的精细化弹簧-四面体单元破碎模型．将多面体颗粒用弹簧-四面体单元离散后, 利用连接线性目录法建立可能接触颗粒对的邻居目录, 采用改进的射线穿透法判断邻居目录中颗粒对是否真正接触．两种算法共用边界盒, 讨论了接触识别算法中特殊的接触类型, 并计算接触力．通过最大拉力准则判断弹簧断裂, 最终获得多面体颗粒的破碎情况, 并对六棱柱颗粒高速冲击刚性边界的破碎过程进行了数值模拟, 研究了不同速度下颗粒高速冲击刚性边界的破碎程度．模拟结果表明, 建立的弹簧-四面体单元破碎模型可以模拟多面体颗粒的破碎过程, 连接线性目录法能够快速建立颗粒系统的邻居目录, 改进的射线穿透法能有效地识别颗粒间各种复杂的接触情况．研究结果表明, 颗粒破碎是从未破碎-快速发展-缓慢发展的过程, 并且速度越大, 初始破碎时刻越早, 破碎发展速度越快, 破碎程度也越严重．数值模拟结果与颗粒冲击破碎实验的结果趋势相符, 计算模型反映了真实情况下颗粒的破碎趋势．改进了的多面体接触识别算法和提出的弹簧-四面体单元破碎模型可以有效地模拟颗粒的破碎过程, 解决颗粒破碎后碎片的真实形状问题．
Abstract_English:To simulate the fracture process of polyhedron particle and to reproduce the real shape of the fragments once the fracture process is completed，the contact detection algorithm of polyhedron is improved，and a fine fracture model of a spring-tetrahedron element is proposed based on the discrete element method. The polyhedron particle was discretized by the spring-tetrahedron element. The linked linear list method was used to establish the neighbor list of the adjacent particle pairs that may be in contact with each other. The improved ray crossing method was applied to determine whether the particle pairs in the neighbor list were actually in contact. Both the algorithms shared the same bounding boxes. Special contact types in the contact detection algorithm were discussed，and the particle-particle contact force was calculated. Spring failure was determined by the maximum tension criterion，and then the fracture process of the particle was obtained. The fracture process of a hexagonal particle impacting rigid wall with high velocity was simulated，and the fracture degrees of these particles at different speeds were studied. The simulation results showed that the fracture model of the spring-tetrahedron element could simulate the fracture process of the particle. Additionally，the linked linear list method could establish the neighbor list of the particle system with a high efficiency，and the improved ray crossing method could efficiently detect various complex contacts between the polyhedral particles. The results indicate that the particle fracture is a process of no fracture-rapid development-slow development. Since，the time required for the initial fracture to occur decreases with an increase in the impacting speed，the fracture develops faster and the fracture degree is more serious. The simulation results are in agreement with the results obtained for particle impact fracture experiment，and the calculation model reflects the fracture development of particles under real conditions. The improved contact detection algorithm and the fracture model of the spring-tetrahedron element can effectively simulate the particle fracture process and solve the real shape problem of the fragments after particle fracture.
Keyword_Chinese:破碎模型; 离散元; 接触识别; 断裂准则
Keywords_English:fracture model; discrete element method(DEM); contact detection; fracture rule

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