摘要
利用分离式Hopkinson压杆试验装置,开展了不同应变率下的磁铁矿石冲击实验。分析了磁铁矿石在动载下的力学特性和破坏裂纹演化过程,揭示了磁铁矿石块度分布规律。研究结果表明:磁铁矿石的动态弹性模量与动态强度的应变率效应显著,在不同应变率下,应力-应变曲线峰后卸载速率以及卸载方式存在差异。随应变率的提高,软化因子(K)减小,磁铁矿石软化程度加深。磁铁矿石强度比例因子λ与ε·1/3呈线性分布,比能量吸收与ε·呈线性分布。磁铁矿石破碎形态具有明显的自相似性,随着应变率提高,磁铁矿石平均块度减小,分形维数增大,磁铁矿石破碎程度加剧,分形维数与应变率、比能量吸收均呈线性分布。通过绘制全对数粒度特征曲线直观地表达了矿石碎块的粒度分布规律,结合块度分布系数(C),进而得出了实现矿石破碎的合理应变率范围。研究成果对于磁铁矿石动载破碎机理分析、破碎块度分布及能耗分析具有重要的参考价值。
The impact experiments of magnetite ore under different strain rates were carried out by a splitting Hopkinson pressure bar (SHPB) equipment.The mechanical properties and the crack propagation of the magnetite ore under dynamic load were analyzed to evaluate the distribution pattern of the fragmentation of the magnetite ore.Experiment results indicate that the strain rate effect of the dynamic elastic modulus and strength of the magnetite ore is obvious.The unloading rates and unloading modes in the post-peak of stress-strain curve are different under different strain rates.With strain rate increasing, the softening factor ( K ) of the magnetite ore decreases and the softening degree increases.Both the relations between the strength scale factor (λ) of the magnetite ore and ε· 1/3, and the specific energy absorption of the magnetite ore and ε· are linear distribution.The broken form of the magnetite ore is of distinct self-similarity that the mean fragment size of the magnetite ore decreases, fractal dimension increases and the magnetite ore is broken strongly with strain rate.The fractal dimension increases linearly both with the strain rate and the specific energy absorption of the magnetite ore.The distribution pattern of the fragmentation of the magnetite ore, which is clearly revealed by means of the total logarithmic curve of the cumulative particle size, combined with the block distribution coefficient ( C ), the reasonable range of the strain rate of the magnetite ore crushing is obtained.The study results provide significant references for the analysis of the crushing mechanism of magnetite ore under dynamic load, the distribution of the fragmentation and the energy consumption.
作者
李占金
郝家旺
甘德清
刘志义
LI Zhanjin;HAO Jiawang;GAN Deqing;LIU Zhiyi(College of Mining Engineering, North China University of Science and Technology, Tangshan 063009, China;School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing, 100083, China)
出处
《振动与冲击》
EI
CSCD
北大核心
2019年第12期231-238,245,共9页
Journal of Vibration and Shock
基金
国家自然科学基金(51374087)
河北省自然科学基金(E2015209176)
关键词
磁铁矿石
SHPB
力学特性
应变率
破坏模式
分形维数
magnetite ore
SHPB
mechanical properties
strain rate
failure mode
the fractal dimension
