A Study on Frictional Effect at Contact Interfaces of Aero-Engine Bolted Joints

Bolted flange joints are extensively used in the aero-engine assembly, for fastening static components, rotors, external accessories, etc. The core functional requirements of bolted joints are to assemble the different parts, prevent the leakages at the assembly interfaces, maintain proper alignment and fit, and to meet the structural integrity requirements. The critical structural integrity requirements could be a load transfer, provide required stiffness and strength, and meet the design life, etc., depending on location of bolted joint deployment. Bolted joint in aero-engine also need to be custom designed with different design configurations and for optimal number bolts, for an assembly interface for minimal weight and to accommodate within the space constraints of aero-engine design, unlike bolted joint applications in conventional industry.  This necessitates the design of different bolted joint configuration like back to back flange, stepped flange joint etc.  It is essential to study the behaviour of load transfer, contact pressure distribution, deformation, and slip at the bolted joint interface to make an effective design of a specific configuration. The objective of present study is to study influence of friction on the load transfer behaviour, contact stress distribution, contact openings, and slip at the bolted jointed interfaces.  Finite element study is carried out at on back to back and stepped flange configurations using ANSYS contact modelling