Amplitude Frequency Characteristics of 'Smart'-Pin Frame System

Abstract

The use of adjustable Amplitude Frequency Characteristics (AFC) approach is a new concept in vibration mitigation, which is developed from frequency detuning technique used in vibration protection against resonance. This non-constant APC can be generated by Magnetorheological (MR) fluid-based pins, so called 'smart pins', which are mounted at beam-column connections. The paper presents a preliminary investigation of a 'smart' -pin-frame system, a single-storey, one bay, steel plane frame with a traditional pin and a 'smart' pin mounted at each beam-column end, whose frequencies can be adjusted by partially 'locking' or 'releasing' the smart pin. To do so, a maximum or zero DC current level is supplied to the smart pin, which respectively transforms the system into either pin-rigid (P-R) or pin-pin (P-P) beam in a frame structure. Experiments, conducted in the Structure Laboratory of the University of Technology, Sydney (UTS) using both a sudden release technique and a shake table, were used to investigate the non-linear dynamic properties and the system AFC prior to their 'proof-of-concept' testings. Preliminary AFC results showed the potential use of the system subjected to harmonic forced vibrations.