To continue improving both performance and durability of gas turbine engines, a better understanding of the structural behavior of components is essential. Though structural capability of all engine componentry is assessed with rigor, critical components such as airfoils, disks, and integrally bladed disks (IBDs) are scrutinized more heavily than others. With advanced, sixth-generation engines requiring novel design concepts and non-conventional manufacturing methods to meet performance demands, the framework for structural assessment must be updated to define acceptable sustainment criteria for critical components. This research opportunity aims to address the need for improved structural characterization that will reduce the likelihood of legacy and developmental gas turbine engine components failing, Structural characterization requiring attention is based on vibration suppression, fatigue behavior analysis, and strength assessment.

Computational and experimental research to understand structural behavior of turbomachinery components is being conducted by the Turbine Engine Integrity Branch (RQTI) in the Aerospace Systems Directorate of AFRL. The research areas include mistuning, nonlinear vibration, applied damping prediction, system identification, damage detection, probabilistic analysis, fatigue life and crack growth predictions, additive manufacturing, thermomechanical fatigue, multiphysics lifing, and development of new structural design approaches. Within these areas are several key research topics that require the integration of experimentation and analysis. Ongoing work consists of modal characterization via finite element methods and bench experimentation, standard fatigue and fracture characterization using mechanical testing and physics-based modeling, novel component and material testing development leveraging reduced order modeling (ROM) and surrogate response prediction, and uncertainty quantification in analysis and experimental methods.

To support the aforementioned research, both experimental and computational facilities are available within RQTI. The Turbine Engine Fatigue Facility (TEFF) is a state-of-the-art research facility that performs structural and dynamic experimentation. The TEFF directly supports Air Force legacy fleets, as well as developmental programs through basic research in the areas of material characterization, vibratory assessment, life prediction modeling, and qualification of advanced measurement techniques. Experimental capabilities in the TEFF include scanning laser vibrometry, advanced geometric optical scanner, digital microscopy, triangulation displacement sensor, ping dynamic frequency analysis, large-to-small scale electrodynamic shakers, high-frequency/ultrasonic shakers, high-temperature induction and resistance ovens, single- and multi-axial servo-hydraulic load frames, traveling wave excitation system, and vacuum spin chamber for small IBDs. The Structural Analysis Group (SAG) is the high-performance computational research area leveraging physics-based understandings from finite element methods and computational fluid dynamics. The integrated work conducted by the SAG utilizes finite element software ANSYS, mathematical programming language MATLAB, executable programming languages Python and LabVIEW, computational fluid dynamics software STAR-CCM, mistuning ROM algorithm MAGMA, and digital twin solid model algorithm MORPH.

 

key words

Turbine engine; Structural dynamics; Additive manufacturing; Fatigue; Mistuning; Damping; Prediction models; Airfoil; Material properties;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral and Senior applicants