Experimental Identification of Modal Parameters in a Semi Aeroelastic Hinged Wing Demonstrator

Abstract

The introduction of a semi aeroelastic hinge (SAH) is motivated by the requirement for higher aspect-ratio wings with favourable aeroelastic characteristics. Variations in aerodynamic stiffness and coast angle across the flight envelope cause the system's modal parameters to shift significantly due to changing stiffness and mass distributions. While computational studies suggest potential flutter instabilities arising from the coupling of the first inner wing bending mode and the wingtip's rotational motion, experimental identification of such structures remains sparse in current literature due to the novelty of the concept. This paper presents the modal identification of a laboratory wing equipped with a spring-supported and actuated hinge designed to emulate SAH in-flight dynamics. By controlling the hinge fold angle and stiffness, the system's modal parameters are experimentally identified across a wide operational envelope and then compared against a computational model. The modes of interest were consistently identified and showed distinct dependence on the SAH demonstrator parameters. Agreement between the experimental and computational modes was limited for some modes and excellent for others. The results of this study serve as a basis for developing in-flight identification procedures and advancing gust-load alleviation technologies.