Performance-Based Inspection Techniques for Turbine Engine Blades and Rotors

HCF is one of the leading causes of engine failure in aircraft. Preventing HCF failures requires accurate determination and avoidance of resonant frequencies in design. Designers use a combination of finite element structural analysis and modal frequency testing to identify the natural frequencies at which components resonate. However, these analyses are typically performed on nominal geometries. While each of the blades in a blade row is designed to the same nominal dimensions with close tolerances, the actual dimensions (and therefore resonant frequencies) of manufactured parts will vary a small amount from blade to blade. Methods for acquiring digital 3D dimensional data of manufactured parts are now available but the process to characterize stress from 3D scans is complex and time-consuming. Each blade requires it own mesh for computational fluid dynamics (CFD) analysis to predict aerodynamic loading, and finite element analysis (FEA) to calculate the blade frequency and stress. The goal herein is to develop methods for streamlining the process for calculating blade vibratory stress for measured airfoils. We propose to develop the techniques to efficiently manipulate the geometry and finite element meshes in order to permit multiple blade stress calculations in much less time than it takes today.