摘要
为研究玻璃球的宏细观冲击特性,该文开展了不同相对密实度玻璃球的一维霍普金森杆(SHPB)冲击试验和离散元-有限差分法耦合数值模拟研究。结果表明:一维冲击荷载下玻璃球经历初始弹性、屈服、颗粒间互锁硬化和颗粒破碎硬化四个阶段。基于耦合数值模拟发现,颗粒平均配位数随着冲击荷载时程不断增加,但增加的速率逐渐下降,其原因是配位数变化取决于孔隙压缩和以旋转为主的颗粒重排,随着试样压缩变形的发展,孔隙压缩和颗粒重排需要克服更大的颗粒间互锁效应,因此逐渐变缓。而试样孔隙率在弹性阶段基本不变,在屈服阶段和互锁硬化阶段近似线性下降,其原因是孔隙率变化受控于颗粒整体移动,弹性阶段颗粒整体移动尚未发展,屈服之后颗粒整体移动产生的孔隙压缩随荷载时程呈线性发展。冲击荷载下,颗粒位移以整体移动为主,相对位移为辅,因此,颗粒位移对试样的初始密实度不敏感。颗粒旋转需要克服周围颗粒的互锁效应,互锁效应取决于试样级配和颗粒粒径,对密实度较敏感。
In order to study the macro and micro impact behavior of glass beads,one-dimensional SHPB impact tests on glass balls with different relative densities were carried out.The coupled numerical model of SHPB impact test was established by discrete element and finite difference methods.The experimental and numerical results indicate that the glass ball experiences four specific phases under one-dimensional load,i.e.,initial elastic response,yielding,lock-up and particle crushing.The average coordination of particles increases with the applied impact load but the increasing rate decreases gradually.This is because the coordination number is determined by both pore compression and particle redistribution which is caused by particle rotation and relative movement.Particle rotation and relative movement become more than more difficult with the compression of granular sample.The porosity of sample remains almost constant in initial elastic response,but decreases approximately linearly in the yielding and lock-up phases(grain redistribution).This is because the porosity is mainly determined by the bulk movement of particles,which causes compression in pores.The bulk movement of particles has not been developed at the initial loading,but after yielding the pore compression caused by the bulk movement of the particles develops linearly with the load history.The particle displacement is dominated by bulk movement;thus it is not sensitive to initial density.The particle rotation and relative movement need to overcome the lock-up effects which are closely related to the particle size distribution,thus they are very sensitive to the relative density.
作者
吕亚茹
吴琳
王媛
张冬冬
黄文雄
苏宇宸
LYU Ya-ru;WU Lin;WANG Yuan;ZHANG Dong-dong;HUANG Wen-xiong;SU Yu-chen(College of Mechanics and Materials,Hohai University,Nanjing,Jiangsu 211100,China;College of Water Conservancy&Hydropower Engineering,Hohai University,Nanjing,Jiangsu 210098,China;College of Field Engineering,Army Engineering University of PLA,Nanjing,Jiangsu 210007,China)
出处
《工程力学》
EI
CSCD
北大核心
2023年第6期245-256,共12页
Engineering Mechanics
基金
国家自然科学基金项目(51779264,11772117)
中央高校科研业务费项目(B200202119)。
