Operational Modal Analysis for Simulated Flight Flutter Test of an Unconventional Aircraft (original) (raw)

Abstract

Abstract: The framework of this research paper concerns a phenomenon called ”flutter” which is a well-known dynamic aeroelastic instability caused by an interaction between structural vibrations and unsteady aerodynamic forces, whereby the level of vibration may trigger large amplitudes, eventually leading to catastrophic failure of the aircraft within a couple of seconds. Flutter prediction and flutter clearance are major issues in the design, development and certification process of an aircraft. Hence, it is mandatory for certification to guarantee that the aircraft is free from flutter throughout the entire flight envelope. Within the framework of the FLEXOP (Flutter Free FLight Envelope eXpansion for ecOnomic Performance improvement) project, an output-only operational modal parameter estimation algorithm in frequency domain has been implemented for monitoring the evolution of the aeroelastic modes for the nearly real-time surveillance of flutter. Therefore an integrated aeroela...

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What is the PolyMAX method and its significance in flutter analysis?add

The PolyMAX method enables output-only operational modal analysis by extracting eigenfrequencies and mode shapes from simulated data. Its application has enhanced real-time surveillance of flutter, notably used in the FLEXOP project.

How does the µ-V method improve the robustness of flutter velocity predictions?add

The µ-V method accounts for uncertainties in structural dynamics and aerodynamic coefficients, computing the worst-case flutter velocity. It demonstrated a reduction in flutter speed by approximately 6.7% due to modeled uncertainties in the FLEXOP aircraft.

What assumptions are made in the equations of motion for the aeroelastic system?add

Key assumptions include neglecting earth rotation and ensuring small deformations using Hooke's Law. The model relies on a decoupled description of rigid and flexible body motions based on linear elastic theory.

How are uncertainties represented in the aerodynamic modal participation model?add

Uncertainties in aerodynamic modal participation are quantified by varying aerodynamic influence coefficients with defined limits. For instance, a 5% variability in the first mode's contribution was illustrated, affecting overall flutter predictions.

What role does the Dryden Wind Turbulence Model play in this research?add

The Dryden Wind Turbulence Model simulates atmospheric turbulence, providing realistic operational excitations for the aircraft during testing. This model is critical for assessing structural response and enhancing the fidelity of flutter analysis.

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