Fatigue crack propagation at aeronautic engine vane guides using the extended finite element method (XFEM)

Abstract

This work presents the numerical modeling and validation of two different fatigue propagation tests that attempt to simulate the crack growth situation that takes place at aeronautic engine vane guides. These vanes, which are cylindrical skins of very thin thickness (few millimeters), are responsible for holding the static blades of both the compressor and the turbine. The union of discs and blades is a very conflictive zone due to high stresses and possible manufacturing defects. The first test designed for this work tries to reproduce crack growth at geometric discontinuities and sharp edges, such as the union between the disc and the blades. The second test tries to reproduce the crack growth situation that takes place in skins of very thin thickness, such as vane guides. First, the experimental set-ups as well as the experimental results are presented. Then, the numerical FE models and simulations -corresponding to the experimental tests that have been performed- are explained. Finally, the comparison between the experimental and numerical results is presented. Crack growth was controlled by optical microscopy and by progressive crack surface heat-tinting. For the numerical simulations, the Extended Finite Element Method (XFEM) implemented in Abaqus® 2017 software has been used. The comparison between the experimental and numerical results shows very good correlation regarding crack shape and number of cycles until failure. The capabilities of the XFEM-based LEFM approach to simulate fatigue crack growth in complex crack fronts are validated.

Keywords:

• Fracture
• fatigue crack growth modeling
• extended finite element method (XFEM)
• linear elastic fracture mechanics (LEFM)
• aerospace

Acknowledgment

The authors are grateful to ITP Aero for the funding received for this work as well as for the material supply.