抄録
Crack bifurcation phenomena depend on loading condition and characteristic of material. Therefore, we try to observe simple crack bifurcation phenomena by the dual loading system. In this study, the method of caustics and a high-speed photography system are used to record the dynamic crack bifurcation phenomena.
At first, the experiments for dynamic crack propagation are carried out under various loads. Occurrence of crack bifurcation depends on load balance in the dual loading system. For the cases of dynamic crack bifurcation and nonbifurcation, the fracture mechanics parameters are evaluated based on the experimental results. For all crack bifurcation cases, the energy flux values at the crack bifurcation moment are almost constant, which indicates an existence of critical material value governing the dynamic crack bifurcation.
Next, the special cases of crack bifurcation are discussed. The asymmetric crack bifurcation is occurred under thesame governing low for dynamic crack bifurcation. Also the fracture mechanics parameters at each crack tip have different values. In one more special case, single crack bifurcates to three propagating cracks. These three cracks start propagating from same material point.
