Experimental and analytical investigation for fatigue crack growth characteristics of an aero-engine fan disc

Crack growth evaluation should be performed to certify that the fan disc is capable of maintaining adequate integrity in presence of cracks. The spin test was carried out using the pre-flawed fan disc to obtain a more intensive insight of crack growth characteristic in the bore area. The variation of the surface crack length was measured by the replication method, and then the crack surface fractography was observed with scanning electron microscope (SEM). Both 3D numerical simulation and rectangular plate model were utilized to predict growth behavior of this crack. The crack surface fractography revealed a typical striated transgranular fatigue fracture characteristic. The comparison of the spin test result and the predicted crack growth showed that the numerical and theoretical analysis provided a good prediction for crack growth behavior for the fan disc. Taking into account the effect of plasticity-induced crack closure, the crack growth disparity at the disk surface and interior was analyzed and as a result, the shape of crack propagation front can be described more realistically.