Effect of a Micro-crack on the Edge Macro-crack Propagation Rate and Path Under Mixed Loads

The solution of a half-plane containing a micro-crack and an edge macro-crack under mixed loads is presented based on the distributed dislocation technique. The complete stress field and stress intensity factors are obtained. The finite element model is established to simulate the macro-crack propagation path. The effect of a micro-crack on the macro-crack propagation is analyzed comprehensively. The results show that the shielding effect region is like two 'petals' under uniaxial tensile load and rotates with the change in micro-crack angle. For mixed loads, the shielding effect region rotates clockwise with the increasing ratio of applied loads tau(infinity) /sigma(infinity). It is like two 'petals' at tau(infinity) /sigma(infinity) <= 2 and divides into two parts from the macro-crack tip at tau(infinity)/sigma(infinity) >= 5. The micro-crack has the attraction effect on the macro-crack propagation path. These results are useful for predicting the fracture or fatigue behaviors of materials containing micro-cracks.