Finite Element Analysis On Testing Dynamic Fracture Toughness Of Rock

The rock has been widely used for coal exploitation engineering,railway traffic engineering,civil construction and mine construction, so it is very imperious to explore an effective method of testing dynamic fracture toughness of rock. It has important theoretical significance, also has very high value of engineering application. However, because of the existence of massive cracks in rock material, it makes the question of rock dynamic fracture more complicated. So there is no uniform standard in studying method of rock dynamic fracture toughness, different testing methods have very different results.The paper gives a new method to test rock dynamic fracture toughness according as mechanic property of rock and the notable advantage of the central cracked circular disk specimen in testing dynamic fracture toughness of brittle materials. This method is using central cracked circular disk specimen in split hopkinson pressure bar. A three dimension dynamic finite element model is built up to simulate the whole experimental system for pure modeâ… dynamic loading. According to the numerical analysis, we can find the change rule of the dynamic stress intensity factors of crack tips, and validate the feasibility of this method. By comparing the near and far field solution of the stress intensity factors of the central cracked circular disk specimen, using the far field solution of the stress intensity factor to characterize dynamic fracture toughness of rock is valid. And then, compare the dispersion of dynamic stress intensity factors, find the appropriate size of specimen, including the diameter,thickness,chamfered edge of specimen and the relative crack length,the shape of crack,the width of crack et al. Consequently, it provides a credible method of testing dynamic fracture toughness of rock.