Anders Karlsson, Ulf Ringertz
DOI Number: N/A
Conference number: IFASD-2017-105
In a recently finished project the ability to design and manufacture advanced wind tunnel models have been addressed as well as the development of tools for analysis of nonlinear aeroelastic phenomena. Experimental static tests of a real aircraft pylon-store test asset indicated a nonlinear behaviour in the sway brace and store interface for low preload cases. This characteristics was then replicated in a model scale with a detailed hardware realisation. A fairly extensive low speed wind tunnel program was performed with different store configurations as well as parameter variations of the sway brace preload and mass properties of the external stores. A failure case with a free-play between the wing tip missile and pylon was also investigated. Small differences were found in flutter speed and amplitude at the neutrally stable condition depending on the preload or introduced free-play. However, when the preload is reduced to half nominal value there was more of a constant amplitude (LCO) behaviour at the critical speed. This could be due to an amplitude dependent structural damping, something which numerically is shown to have a quenching effect.