Abstract

The overall aim of this dissertation is to conduct a comprehensive investigation on the design optimization for passive and semi-active vibration suppression of beam-type structures utilizing the Tuned Mass Damper (TMD) and Semi-Active Mass Damper (SAMD) to prevent discomfort, damage or outright structural failure through dissipating the vibratory energy effectively. The finite element model for general curved beams with variable curvatures under different assumptions (including/excluding the effects of the axial extensibility, shear deformation and rotary inertia) are developed and then utilized to solve the governing differential equations of motion for beam-type structures with the attached TMD system. The developed equations of motion in finite element form are then solved through the random vibration state-space analysis method to effectively find the variance of response under stationary random loading. A hybrid optimization methodology, which combines the global optimization method based on Genetic Algorithm (GA) and the powerful local optimization method based on Sequential Quadratic Programming (SQP), is developed and then utilized to find the optimal design parameters (damping, stiffness and position) of the attached single and multiple TMD systems. Based on the extensive numerical investigation, a design framework for vibration suppression of beam-type structures using TMD technology is then presented. An in-house experimental set-up is designed to demonstrate the effectiveness of the developed optimal design approach for vibration suppression of beam-type structures using TMD technology. Next, the Magneto-Rheological (MR) fluid damper is utilized to design the SAMD system. A new hysteresis model based on the LuGre friction model is developed to analyze the dynamic behavior of large-scale MR-damper (MR-9000 type) accurately and efficiently. The gradient based optimization technique and least square estimation method have been utilized to identify the characteristic parameters of MR-damper. Moreover, based on the developed hysteresis model, an effective inverse MR-damper model has also been proposed, which can be readily used in the design of semi-active vibration suppression devices. The controller for SAMD system using MR-damper is designed based on the proposed inverse MR-damper model and H2 /LQG controller design methodology. The developed SAMD system along with the MR-damper model is then implemented to beam-type structures to suppress the vibration. It has been shown that the designed SAMD system using MR-damper can effectively suppress the vibration in a robust and fail-safe manner.