Prediction analyses of stress uniformity time in rock SHPB test
PING Qi1,2, MA Qin-yong1,2 , YUAN Pu1
1. Ministry of Education’s Engineering Research Center of Mine Underground Projects, Anhui University of Science and Technology, Huainan, Anhui 232001, China; 2. Key Laboratory Being Built by Anhui Province and Ministry of Education for Coal Mine Safety and Efficient Exploitation; Anhui University of Science and Technology, Huainan, Anhui 232001, China
Abstract：According to one-dimensional stress wave theory, the calculation formula for stress distribution in rock specimen was obtained by analyzing the propagation of elastic stress wave in split Hopkinson pressure bar (SHPB) test and some influence factors or rulers of time for stress equilibrium in specimen were also investigated. For three kinds of mine rock specimens loaded by variable cross-section SHPB apparatus, its stress uniformity and time for stress equilibrium were discussed under smoothed actual incident wave or theoretical trapezoidal incident wave which had same rise time with actual incident wave. It was found that using variable cross-section input bar could ensure specimens achieve stress equilibrium before reaching stress peak and meet the valid requirements in the assumption of stress uniformity. Results showed that when rise time was same, theoretical trapezoidal incident wave could replace the actual incident wave to forecast stress uniformity and time for stress equilibrium in rock specimens. The results would give some references in SHPB test for similar brittle materials.
2013, Vol. 32 
