마찰 감쇠기를 이용한 트러스 구조물 진동제어 시 감쇠기의 마찰 특성에 따른 최적모드감쇠제어 성능 평가

Abstract

Space truss structures are likely to subject to transient vibrations in low frequencies, which need to be reduced as quickly as possible for stable mission of space equipments. Friction damping is one of the attractive vibration control methods owing to simple mechanism and large damping capacity. However, passive approach has a limitation because energy is no longer dissipated once sticking occurs. This limitation can be overcome by semi-active control, in which the normal force is adjusted. Although various studies have been carried out on the semi-active friction approaches, global damping characteristic of the friction damper-test structure was not investigated. In this study, the optimal modal damping(OMD) control is applied to damp the first bending mode of truss structure. The key concept is to represent the equivalent damping ratio of the friction damper-truss structure system in terms of normal force and vibration amplitude and, then, to control the normal force for maximum damping ratio as the amplitude decreases. Since, however, the equivalent damping is derived based on elasto-plastic model, control performance would be worsen as difference between the model and the real friction becomes larger. Dependence of the OMD control on characteristics of the friction damper is presented through numerical simulations.