A Novel Semiactive Variable Stiffness Device and Its Application in a New Semiactive Tuned Vibration Absorber

An innovative design for a semiactive variable stiffness (SAVS) device is presented in this paper. This beamlike device is capable of altering its stiffness in a smooth manner between minimum and maximum levels by using the variations of moment of inertia of an area as it rotates around a normal axis passing through its centroid. Analytical expressions for the stiffness of the proposed device have been derived. As an application of the SAVS device in engineering, a semiactive tuned vibration absorber (SATVA) is developed that is capable of real-time retuning and operates effectively in broadband frequency excitations. A single-degree-of-freedom (SDOF) system coupled with the SATVA is considered. The excitation force is assumed to arise from a rotating unbalance whose frequency varies with a constant acceleration and then reaches a steady-state operating condition. The absorber stiffness is varied to tune the absorber's natural frequency to the forcing frequency in real time. The effectiveness of SATVA is evaluated by comparing the system's responses with those of the system with passive vibration absorber. The results show the salient features of the proposed SATVA in transient response reduction compared with the traditional passive vibration absorber. DOI: 10.1061/(ASCE)EM.1943-7889.0000235. (C) 2011 American Society of Civil Engineers.