[Article Information]

Dynamic Properties and Failure Modes Analysis of Magnetite Ore under Dynamic Loading



LIU Hao-shan ,ZHANG Zhi-yu ,LI Xiang-long ,HUANG Yong-hui ,WANG Jian-guo




Abstract


Abstract: In view of the problem that mining and crushing of magnetite ore require huge energy consumption, the split Hopkinson pressure bar( SHPB) is used to test and analyze the dynamic mechanical properties and energy dissipation characteristics of magnetite ore during crushing process under different strain rates. Meanwhile,the complete dynamic failure process of the sample is simulated by ANSYS /LS-DYNA software. The results show that the dynamic compressive strength of the magnetite ore samples has a significant strain rate correlation,and increases from 126. 77 MPa to 220. 62 MPa when the strain rate ranges from 43. 94 s - 1 to 147. 75 s - 1 . Besides,The analysis of energy transfer law shows that the increase trend of reflected energy become more obvious with the increase of incident energy,and the maximum proportion accounts for about 22% of the total incident energy. However,The increase trend of transmission energy become weaker,and the proportion of transmission energy decreases from 78% at low incident energy to 38% at high incident energy. At the same time,the dissipated energy used for specimen crushing increases gradually,which has a linear relationship with the incident energy. The failure mode changes from the splitting failure at low and medium strain rates to crushing failure at a high strain rate. In terms of the crushing scale, most of the fragments at low and medium strain rates are large,while the fragments at high strain rates are small and mostly fine-grained and needle shaped. Numerical simulation results indicate that the initial failure is caused by the " cross" shaped reflected tensile waves on the incident end of the specimen. The results of this study can provide a reference for judging the difficulty of dynamic crushing of magnetite ore and improving the efficiency of rock breaking by impact.



Key words: hopkinson pressure bar; magnetite ore; dynamic characteristics; failure modes; numerical simulation





Chinese Information


标题: 动载下磁铁矿石的动力学特性及破坏模式分析



作者: 刘浩杉,张智宇 ,李祥龙 ,黄永辉 ,王建国



摘要: 针对磁铁矿石在采选和破碎过程中耗能巨大的问题,借助分离式霍普金森压杆( SHPB) 试验装置, 对磁铁矿石进行不同应变率条件下的冲击压缩试验,分析磁铁矿石的动态力学特性及其破坏过程中的能量 耗散特征,并借助 ANSYS /LS-DYNA 软件模拟试样完整动态破坏过程。研究结果表明: 磁铁矿石试样的动态 抗压强度具有显著的应变率相关性,应变率从 43. 94 ~ 147. 75 s - 1 ,其动态抗压强度从 126. 77 MPa 提高到 220. 62 MPa。能量传递规律分析表明,随着入射能的增大,反射能增长趋势增大,最大占比约占总入射能的 22%; 而透射能增长趋势减小,且透射能占比从低入射能下的 78%降低至高入射能下的 38%,用于试件破碎 的耗散能量逐步增多,与入射能呈线性关系。其破坏模式从中低应变率下的劈裂破坏转为高应变率下的压 碎破坏,从破碎尺度来看,中低应变率下碎块多为大块状,而高应变率下碎块尺度较小且多呈细粒状及针状。 数值仿真计算表明试件最开始发生破坏是由试件入射杆端面的“十字”反射拉伸波引起的。研究结果可为 判断磁铁矿石动力破碎的难易程度以及提高冲击破岩效率提供参考。



关键词: 霍普金森压杆; 磁铁矿石; 动力学特性; 破坏模式; 数值模拟



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