Safety design method of fan rotor system in aeroengine due to extreme loadings

Fan blade loss is the most serious condition of typical extreme working conditions in turbofan engines. The transient huge unbalance force leads to the complicated and destructive vibration response of the rotor system. The paper proposed a set of safety design method for the rotor system, which ensured the engine to stop safely after the fan blade lost. The variable stiffness supporting structure at the rear of the fan was presented and its parameters were optimized through dynamic characteristics calculation. The results revealed that the vibration response of the rotor system could be suppressed during the speed reduction process. The spherical matching surface between the bearing ring and the rotation shaft could reduce the impact of the large shaft deformation, and enhanced the bearing´s safety.