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 引用本文: 熊迅, 李天密, 马棋棋, 方继松, 郑宇轩, 周风华. 石英玻璃圆环高速膨胀碎裂过程的离散元模拟[J]. 力学学报, 2018, 50(3): 622-632.
Xiong Xun, Li Tianmi, Ma Qiqi, Fang Jisong, Zheng Yuxuan, Zhou Fenghua. DISCRETE ELEMENT SIMULATIONS OF THE HIGH VELOCITY EXPANSION AND FRAGMENTATION OF QUARTZ GLASS RINGS[J]. Chinese Journal of Theoretical and Applied Mechanics, 2018, 50(3): 622-632.
 Citation: Xiong Xun, Li Tianmi, Ma Qiqi, Fang Jisong, Zheng Yuxuan, Zhou Fenghua. DISCRETE ELEMENT SIMULATIONS OF THE HIGH VELOCITY EXPANSION AND FRAGMENTATION OF QUARTZ GLASS RINGS[J]. Chinese Journal of Theoretical and Applied Mechanics, 2018, 50(3): 622-632.

## DISCRETE ELEMENT SIMULATIONS OF THE HIGH VELOCITY EXPANSION AND FRAGMENTATION OF QUARTZ GLASS RINGS

• 摘要: 采用离散元算法模拟了石英玻璃圆环受到外加动态载荷时的力学行为. 首先基于flat-jointed粘结模型,通过标准的单轴拉压、三点弯曲等数值实验来标定了石英玻璃的微观参数. 在此模型基础上,数值模拟再现了石英玻璃圆环在不同应变率下的膨胀碎裂过程. 为定量分析数值模拟结果,需要准确确定圆环的碎裂发生时刻. 模拟发现：伴随着石英玻璃圆环的断裂,圆环外表面粒子径向膨胀速度的时程曲线会发生突然升高然后下降的跳动;详细分析表明,这种跳动源自周向的脆性断裂诱发的卸载波(周向拉伸应力急剧下降)以及伴随而来的泊松膨胀,这种径向速度跳动现象为实验中检测脆性断裂发生时刻提供了可能. 进一步的数值研究表明：(1)石英玻璃圆环的断裂应变随着应变率的提高而增大,与韧性金属材料的膨胀环实验结果一致;(2)石英玻璃圆环的碎片平均质量随着应变率的增大而减小;(3)数值计算获得的碎片平均尺寸与已有的理论和实验结果比较吻合. 利用液压膨胀环实验装置对石英玻璃圆环进行了验证性实验,回收得到的碎片形貌及碎片个数与数值模拟的结果基本一致.

Abstract: The mechanical behavior of quartz glass rings under internal velocity impact is simulated by using discrete element method (DEM) based on the flat-jointed bond model. The microscopic mechanical parameters of the quartz glass ring were determined by comparing the standard uniaxial compressive/tensile and three-point bending numerical test results with the experimental results. Using these material parameters, the fragmentation processes of quartz glass rings under different impact velocities were numerically simulated. The numerical results showed that: the failure time of the quartz glass ring corresponded to a rebounding of the radial velocity, macroscopically this timing is coincident with the rapid drop of average stress. This radial velocity rebounding is attributed to the unloading waves incited from the brittle cracking of the tensile specimen, and can be used in the numerical analysis as the failure point. Detailed numerical tests and analysis showed that: (1) The fracture strain of quartz glass ring increases with the increase of strain rate, a phenomenon consistent with experimental observations for ductile materials; (2) The average mass of the quartz glass ring decreases with the increasing strain rate; (3) The average fragment size in the simulation was consistent with the theoretical and experimental data in other papers. An experiment device of liquid-driven expanding ring was used to conduct preliminary tests. The morphology and the number of fragments recovered from real tests are consistent with the numerical simulations.

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