based in shape-memory alloy (SMA)

133 Pages·2016·13.31 MB·English

João Miguel Matos Nunes
Licenciado em Ciências da Engenharia Civil
Adaptive Tuned Mass Damper (ATMD)
based in shape-memory alloy
(SMA) elements.
Dissertação para obtenção do Grau de Mestre
em Engenharia Civil - Perfil de Estruturas
Orientador: Professor Doutor Filipe Amarante dos Santos
Professor Auxiliar, FCT/UNL
Júri:
Presidente: Prof. Doutora Zuzana Dimitrovová
Arguente: Prof. Doutor Corneliu Cismasiu
Vogal: Prof. Doutor Filipe Amarante dos Santos
Março de 2016

“Copyright” João Miguel Matos Nunes, FCT/UNL e UNL
A Faculdade de Ciências e Tecnologia e a Universidade Nova de Lisboa têm o direito, per-
pétuo e sem limites geográficos, de arquivar e publicar esta dissertação através de exemplares
impressos reproduzidos em papel ou de forma digital, ou por qualquer outro meio conhecido
ou que venha a ser inventado, e de a divulgar através de repositórios científicos e de admitir a
sua cópia e distribuição com objetivos educacionais ou de investigação, não comerciais, desde
que seja dado crédito ao autor e editor.
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To my grandfather, Prof. Rogério Sanches de Matos
"Só devemos fazer aquilo que realmente
enche o nosso coração de entusiasmo.
Se deixamos isso de lado, se adiamos o
momento de viver aquilo que sonhamos,
perdemos a energia necessária para
qualquer transformação importante na
nossa vida."
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Acknowledgments
The present dissertation arises, not only from extensive hours of study, hard work and dedica-
tion, butalsoastheresultofalongacademicjourney, thatwouldnothavebeenaccomplished
without the support and assistance from many people who have either helped me or encour-
aged me.
Iwouldliketoexpressmydeepestandheartfeltrecognitiontomyadviser,ProfessorFilipe
Amarante dos Santos for the support, knowledge transmission and availability demonstrated
throughout the development of this thesis.
I would like to thank Engineer Mirko Maraldi and Professor Luisa Molari, not only for
their academic support, but also for the availability and quality care provided during my
abroad study experience in Italy.
I would also like to thank Mr. Alberto Cambalacho for the assistance in the preparation
of the supports used in the experimental campaign.
I leave words of appreciation to my colleagues, Inês de Carvalho, Pedro Castanho, Bruno
Alcobia, Daniel Ferreira, Filipe Loureiro and André Taveira, with whom I had the pleasure
of working with and share true friendship moments along the way.
I am also indebted to my comrades André Martins, Nuno Cabral, André Jorge, Diogo
Canelas, Pedro Palma, Rafael Silva, Tiago Gonçalves, André Palminha, Tomás Campos and
all those omitted by mistake or forgetfulness, for their support and contribute to my growth
as an engineer and mainly as human being.
A special thanks to Mafalda Aquino for the unconditional support in the good and bad
times, throughout my entire academic career.
Finally, I must express my gratitude towards my dear mother Teresa Matos, my father
CarlosCoito, mysisterJoanaNunesandtherestofmyfamilyfortheirlove, unfailingsupport
and inspiration.
I hope this thesis may be an encouragement for the younger members of my family (Fran-
cisco and Mariana), and for all the people who read or work with it.
João Miguel Matos Nunes, March 2016
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Abstract
The unique features of shape memory alloys (SMA) gives them an unmatched ability to be
implemented in several fields of engineering. Considering their phase shift capacity, when
thermoelectrically driven, SMAs assume an elastic modulus variation predicated upon two
key parameters - stress and temperature.
Based on the above statement, the present dissertation aims to develop a new vibration
control system, which makes use of SMAs in order to extend and improve its operational
domain.
Initially,anexperimentalcampaignisdevelopedinordertodesignamappingoftheelastic
modulus of a FLEXINOL (cid:13)R SMA sample.This mapping seeks to explore and an optimize the
inclusion of shape memory alloys in vibration control systems.
In a second step, two types of ATMDs (Suppressor and TMD) are mathematically studied
in order to comprise the insertion of a SMA element in the control system.
Considering the main purpose of this thesis, a particular case study structure was chosen
to carry out the implementation of the new vibration control system. The selected structure
consists in a footbridge built over an important highway located in the Lisbon city center,
Portugal. At this stage, both the design of the SMA element and the subsequent operational
limits are presented.
Afterwards, a numerical model computed in MATLAB (The Mathworks, 2014) is devel-
oped to simulate the behavior of a two degrees of freedom (TDOF) system. This one provides
thesystem’sbehavior(structure+ATMD)towardsapredefinedharmonicrequest,evaluating
the effects of the implementation of the new vibration control system.
Usingthe abovementionednumerical model, aninfluence analysis ofbothcontrol systems
was carried out. Several comparisons between the variants of each ATMD (Suppressor and
TMD) where drawn, showing the positive and negative aspects of their action. In the end, a
single numerical model, with the ability to excite the structure, read its behavior, identify the
vibration frequencies and properly tune the control system in real time, performed a complete
structural analysis.
Finally, a concluding chapter is presented, where the obtained results are discussed. This
chapter also mentions the main future development prospects, that may be considered in
studies conducted by other researchers.
Dissertation produced in LATEXsoftware.
Keywords:
Shape memory alloys, Elastic modulus, Vibration control systems, Suppressor, Tuned mass
damper, Variable stiffness.
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