59996 - An Understanding of Stress and Pretension Behaviour of Aero Engine Rotor Bolted Joint 

Bolted joints in gas turbines are used commonly to connect the parts of dissimilar materials, facilitate assembly, dis-assembly, and also to achieve modular concept adopted for advanced aero engines. In gas turbine engine, there are many rotating and stationary parts that are subjected to an extreme working environment. Bolted joints should have sufficient strength to support the mating parts such as safety critical fan/turbine discs, drums, and shaft assembly. Bolted joints are designed to avoid flanges separation and slippage. This paper attempts to understand the challenges faced in designing typical fan disc rotor plain flange type bolted assembly and structural integrity aspects under various thermo-mechanical operating loads. The understanding of stiffness of the bolt and joint members is necessary to evaluate the performance of the joint assembly. Based on the literature, different approaches are used for estimating member stiffness to compare with finite element results. The effect of external loads such as thermo-mechanical loads on pretension behavior of bolted joint is studied with the help of standard commercial software platform ANSYS. Bolted joint preload loss has been assessed via the standard analytical method and validated with 3D finite element approach. This paper enables designer a quick understanding of rotor bolted joint behavior and finalization of gas turbine rotor layout before going into complex time consuming 3D finite element modelling and nonlinear stress analysis.