Development of a System Framework for Optimal Design of Tuned Mass Dampers
Date Issued
2012
Date
2012
Author(s)
Yang, Chu-Hsien
Abstract
In recent years, tuned mass dampers have been widely used in structures to reduce the discomfort induced by vibration. However, the optimization of design variables for tuned mass dampers is very significant. There are some design formulas or closed form solutions for the structure without inherent damping, and simplified the structure as an one-degree-of freedom mass system. But in real structures, it is no possible for a structure without any damping and only one-degree-of freedom existed. Therefore, this thesis uses finite element package as the analysis engine to model and analyze the structure and then use the optimization tool to find the optimization variables in order to find a better solution to design tuned mass damper for any objective function.
In this thesis, we derive the motion equation of the system with TMDs first, including different type of TMDs or system with different degree of freedom. While analyzing the response of system with TMD, transfer functions are always used. From transfer functions, we can understand the response of system in the frequency domain.
Then we will introduce the design variables of TMD, for example, mass ratio, damping ratio, tuning frequency ratio and any variable needed like location of TMD. And introduce the objective function of TMD design problem. The root mean square of displacement or the peak value of response in frequency domain is often chosen.
Then the system framework is developed in chapter 4.
First of all, the optimal framework is verified by using a SDOF system without damping and validated the result of system with damping by iterative method and the proposed result in the reference paper. Secondly, make some discussion about series type tuned mass damper. Even if series type tuned mass damper is more effective than classic TMD, it will lose efficiency while the mistake in frequency ratio. So we adjust the form of objective function in order to improve the robustness of series type tuned mass damper. And then ,if we take force into account , we can get better result under the force we considered. Except SDOF system, MDOF systems like plate and beam are designed, too. At last, a ten-DOF system with a TMD or two TMDs is to make sure the feasibility of framework.
According to the aforementioned, the framework constructed is performance well in TMD design problem.
Subjects
tuned mass damper
optimization problem
finite element analysis
Type
thesis
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