| The research of rock dynamic question is a frontal topic in rock mechanics, up to now, there are many difficulties in testing the dynamic mechanics properties of rock not only in theory but also in measure technique. So finding or establishing new methods for testing rock dynamic properties becomes an urgently question to be resolved in the rock engineering.In this paper, the flattened Brazilian disc samples were first used in the dynamic split tests. The dynamic split tests of marble using both ordinary Brazilian disc and flattened Brazilian disc were performed at wide range of strain rate(14.6s-1 —163s-1) with split Hopkins pressure bar(SHPB) of 100mm diameter. With the analysis of finite element method we deduced and got the dynamic tension strength for different sizes of marble and gained the typical failure mode of the Brazilian disc and the flattened Brazilian disc. The paper also researched the dynamic tension strength influenced by the flat ends of the sample, strain rate, projectile speed, pressure, and temperature. It is a simple, effective and ideal method to stick strain gages on the center of the sample in order to gain the dynamic tensile strength for brittle materials. In addition, from a series of electrical resistance strain gauges stuck on the sample surfaces along the loading diameter to record the strain histories, we could detect the initiation strain, the time and position of the crack initiation, and infer the consequence and the velocity of the crack propagation.In addition, based on analysis of finite element method, the superposition integral method was also introduced to calculate the dynamic stress concentration factor.
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