DYNAMIC FRACTURE CHARACTERISTICS OF HIGHLY BRITTLE MATERIALS BY USINGINSTRUMENTED CHARPY IMPACT TEST

In This study we investigate the dynamic fracture characteristics of a tungsten carbide cobalt (WC-6wt%Co) composite material. The dynamic f racture initiation toughness and some of the dynamic fracturing charac teristics are evaluated by using the Instrumented Charpy Impact Testin g (ICIT) procedure. The dependence of measured time-to-fracture on the tup impact velocity and the dynamic fracture toughness for the WC-6wt %Co composite material are obtained by using ICIT. The effect of the l oading rate on fracture initiation toughness is found to be negligible when the time-to-fracture is on the order of 50 mu sec. At significan tly higher rates of loading it is impossible to determine the apparent dynamic fracture initiation toughness because of the influence of the inertia force on fracture loading. It is found that the impact veloci ties affect the time-to-fracture significantly at lower impact velocit ies for various engineering materials. It is shown that with the decre ase of tup impact velocities the time-to-fracture is increased and the dynamic fracture initiation toughness converges to static fracture to ughness.