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