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Smart Vibration Control of Fluid Storage Tanks via Magnetorheological Dampers

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Thesis(38.45 MB)

Date

2025

Authors

Aghakouchaki Hosseini, Seyed Ehsan

Supervisor

Beskhyroun, Sherif
Tookey, John

Item type

Thesis

Degree name

Doctor of Philosophy

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Publisher

Auckland University of Technology

Abstract

Fluid storage tanks play a pivotal role in strategic industries, and hence their dynamic behaviour and damage possibilities have been the focus of attention of research communities for decades. Water supply and storage systems, wineries and dairy products industries, refineries, hospitals, and petrochemical industries are among the most important industries in which these structures are employed. The dynamic behaviour of these structures is very complicated in that it is involved with the fluid-structure interaction phenomenon. The simplified mechanical model is the most used technique for defining this complicated behaviour that has widely been utilised in the seismic design codes of many countries for the analysis and design of these tanks. This method provides the lowest computational cost at the expense of inflicting some inaccuracies on the structural response estimation of the fluid tank. Many different energy-dissipating and seismic protection devices have been investigated in the literature by many researchers for fluid storage tanks. However, the focus of all of these devices has been on the application of passive control devices such as base isolators or baffles, to name but a few. The volume of experimental investigations done in this field is not comparable to the theoretical research work. Also, compared to the amount of theoretical research on passive systems, less has been done on the application of active control systems for these structures. On the other hand, passive and active systems face some drawbacks in terms of adaptability, robustness, and reliability in the event of power failure during severe seismic occurrences. Semi-active control mechanisms combine the advantages of both of these systems and remove their drawbacks. Among different semi-active control systems innovated in the literature, magnetorheological (MR) dampers, due to their special characteristics, have found successful applications in various industries. These dampers require a very low power source ($0-3\; or\; 5 V$), are fail-safe in that in the absence of a power source they turn into passive control systems and continue dissipating the external energy, having a wide operational temperature make them suitable for both internal and external applications. Applications of these dampers include civil structures and infrastructures, the automotive industry, prosthetic applications, and robotics, among others. Nonetheless, for the nonlinear hysteretic nature of these dampers, analysing their dynamics is more complicated than other control mechanisms. In this research, first, a series of experimental investigations were conducted on a highly flexible full-scale flat-based stainless steel fluid tank to understand the dynamic behaviour of these structures. Then, a series of numerical investigations were applied to a legged flexible cylindrical stainless steel fluid tank equipped with an MR damper using different semi-active control designs. Finally, a series of numerical and comprehensive experimental tests were conducted over a rigid legged cylindrical stainless steel fluid tank with and without the application of MR dampers. Numerical and experimental tests were applied using seismic records of real ground motions that occurred in the past in different countries with different frequency contents. In the case of the rigid legged cylindrical tank, a new set of equations representing the dynamics of the rocking tank was developed to analyse its dynamic behaviour and control the fluid-tank system. Two software platforms were developed based on MATLAB and SIMULINK. The first software can be used for signal processing of the experimental results using the sensory system and extracting the natural frequencies of the system. The second software can perform data acquisition and control system design over the system using the sensory system. To control the fluid-tank-MR system, different model-based designs optimised with Hunger Game Search as a new metaheuristic search tool were employed. However, real-world phenomena can hardly be put into precise closed-form formulae. Moreover, the complex behaviour of the dynamical system, time-varying characteristics and degradation of the system over time, and stochastic nature of the external excitations diminish the application of model-based control system designs. Here is when the data-driven control systems come into play. Online real-time semi-active data-driven adaptive control techniques have been developed and applied to these systems to make the application of MR dampers for making seismic-resilient fluid tanks as optimal as possible. Results of numerical and experimental investigations of equipping the fluid tank with MR dampers demonstrate the promising potential of these dampers over other systems for seismic response mitigation, retrofitting, and enhancing the structural responses of fluid tanks under the base excitations. Developed methods and techniques in this research have a low computational cost, reasonable accuracy, and proper performance, which makes them suitable for deployment on micro-controllers for making autonomous control devices to be applied to practical applications.

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http://hdl.handle.net/10292/19102

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