Life Prediction of a Turbine Engine Blade to Disk Attachment Under Coupled Thermo-Mechanical Fatigue

Abstract

Life prediction of turbine engines is crucial part of the management and sustainment plan to aircraft jet engine. Fretting is one of the primary phenomena that leads to damage or failure of blade-disk attachments. Fretting is often the root cause of nucleation of cracks at attachment of structural components at or in the vicinity of the contact surfaces. It occurs when the blade and disk are pressed together in contact and experience a small oscillating relative displacement due to variations in engine speed and vibratory loading. It is a significant driver of fatigue damage and failure risk of disk blade attachments. Fretting is a complex phenomenon that depends on geometry, loading conditions, residual stresses, and surface roughness, among other factors. These complexities also go beyond the physics of material interactions and into the computational domain. This is an ongoing effort, and the Author has been working on computationally modeling the fretting fatigue phenomenon and damage in blade-disk attachment. The model has been evolving in the past few years, and it has been addressing various fretting conditions. The present effort includes the thermal effect and temperature fluctuation during engine operation, and it models the effects of blade to disk attachment’s thermal conditions and its influence on fretting fatigue damage. It further extends the earlier model to include a coupled fatigue damage model. It allows modeling higher speeds and longer durability associated with blade disk attachments. Finally, to demonstrate its capabilities and taking advantage of experimental validation model, the most recent numerical simulations will be presented.