Non-wind-induced nonlinear damping and stiffness on slender prisms: a forced vibration-pressure balance

The non-wind-induced additional nonlinear damping and stiffness of a spring-suspension system (under wind-off conditions) would significantly influence the prediction of aeroelastic response. This study proposes a forced vibration technique to identify the non-wind-induced nonlinear damping and stiffness of both vertical and inclined prisms. The forced vibration-pressure test was performed to observe the non-wind-induced pressure at first. It was observed that the pressure was remarkably affected by the amplitude of structural oscillation, and the corresponding non-wind-induced force is thus nonlinear. A procedure is then proposed to identify the non-wind-induced nonlinear damping and stiffness of the prisms from the tested nonlinear forces. The results yielded by the proposed procedure in terms of a vertical prism has been verified by comparing the response predicted by the unsteady aerodynamic force with/without the non-wind-induced nonlinearities with the measured response. Moreover, the non-wind-induced nonlinearities of inclined prisms have been tested by using the proposed forced vibration technique, which also suggests a mathematical model of the identified results for the purpose of convenience.