Experimental Amplitude-Dependent Characterization of the TiltRotor Aeroelastic Stability Testbed

This paper investigates the amplitude-dependent characteristics of the TiltRotor Aeroelastic Stability Testbed. The recovery rate, MultiProny, and Stockwell transform methods are employed to measure nonlinear effects in the system, overcoming the limitations of conventional methods like logarithmic decrement, moving-block analysis, and Prony series that assume linear (amplitude-independent) behavior. The proposed methods reveal amplitude-dependent trends that conventional methods obfuscate, providing deeper insights into tiltrotor dynamics. A comprehensive study of ground vibration and wind tunnel test data highlights reduced local damping and frequency at larger response amplitudes for various blade materials, rotor speeds, and pitch-flap coupling parameters. This study offers novel analysis capabilities to support design and advances the understanding of tiltrotor nonlinear dynamics.