RESEARCH ON ROBUSTNESS ANALYSIS AND EVALUATION METHOD OF INTER-SHAFT BEARING-REAR JOURNAL OF LOW PRESS TURBINE SYSTEM

The bearing outer ring with a flange is often used in advanced aero-engines, for the purpose of reducing weight of the engine and improve impact resistance. Cons and pros, in the working process, the rotor is subjected to complex loads such as centrifugal forces, periodic impact excitation and lateral inertia forces caused by overload on rotor. When the bearing is operating under heavy loads, a relatively large deflection occurs in the outer ring, causing deformation incoordination between the outer ring and rear journal. As a result, damage accumulation and structural failure such as wear、sliding and fatigue may occur on the contact interface. This survey gives an insight to the deformation distribution and other contact characteristics of the interfaces in the Inter-shaft bearing outer ring - the low pressure turbine rotor system (ISBLPT) in detail, in order that stable contact in the connection structure is ensured with a reasonable structural design scheme. For typical ISBLPT, a dynamic model considering the interfacial contact characteristics of flange bolt was promoted. Then, based on possible failure modes, a contact damage assessment method and structural system robustness evaluation method is proposed. The results show that different loads in inter-shaft bearing-rear journal system will lead to different damage failure modes, leading to uncertain damage failure modes in engine operation. And the change of interface contact characteristics will also have a significant impact on the stiffness characteristic.