1 Design and experimental study of a hybrid vibration absorber for global vibration control M.H. Tso, J. Yuan, W.O. Wong Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong ABSTRACT A simple and practical hybrid vibration absorber (HVA) is proposed for global vibration control of flexible structures under random stationary excitations. The HVA, regulated by a pole placement controller, uses a linear translational feedback signal to synthesize active moment via a moment actuator. It is shown, analytically and experimentally, capable of damping vibration in the entire primary structure. While the passive tuned mass damper (TMD) can suppress tonal vibration in the primary structure at the vicinity of the coupling point, it enhances vibration at other locations and other frequencies. The presented HVA, in contrast, can provide more than 48% extra broadband attenuation on vibrations at multiple points when compared with the passive TMD in experimental verification on a beam structure. Up to 85% extra broadband attenuation can be observed at the coupling point. The proposed HVA is a simple and economic alternative for engineers to retrofit the conventional TMD to a higher performance HVA for damping vibrations at multiple locations of the primary structure. Keywords: System identification, Global vibration control, Vibration absorber, Hybrid control 1. INTRODUCTION The viscous damper is a well-known, effective and economic device for attenuating vibrations in structures like frames [1, 2] and bridges [3-6]. Practically, a viscous damper may be mounted between two vibrating structures in order to damp relative motion [1-6]. It is also possible to mount a viscous damper between a vibrating structure and a relatively “fixed” base such as ceiling or ground to be a "hooked damper" [7, 8]. No matter which mounting method is used, a viscous damper needs a backed-up point at one end. This restriction may limit the applicability of viscous dampers in some mechanical structures with free-end boundaries, or some applications where it is impossible to find nearby rigid supports. The tuned mass dampers (TMD), on the other hand, are widely used for structural vibration control [9-13]. Figure 1 shows a TMD for vibration control in many skyscrapers, such as the "Taipei 101". It only requires a point of attachment instead of a point of rigid support. The vibration of the primary structure will cause the suspended mass to swing. As a result, tensions in the suspension This is the Pre-Published Version.