Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 128-132). Also available in electronic version.

Thesis (M.Sc.)--City University of Hong Kong, 2006. / "Master of Science in Materials Engineering & Nanotechnology dissertation." Title from title screen (viewed on Nov. 23, 2006) Includes bibliographical references.

Thesis (M.Sc.)--City University of Hong Kong, 2005. / At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.

Thesis (M.Sc.)--City University of Hong Kong, 2005. / At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 101-106). Also available in electronic version.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 249-257).

[pt] Motivado por aplicações na àrea de materiais e estruturas inteligentes, este trabalho apresenta resultados de um estudo sobre a resposta dinâmica de sistemas mecânicos contendo elementos com memória de forma Inicialmente é realizada uma revisão crítica de algumas teorias formenológicas que procuram descrever os efeitos de memória de forma e pseudoelasticidade associados a transformações martensíticas tamoelásticas. Duas destas teorias são utilizadas na modelagem de uma mola helicoidal. O comportamento dinâmico de um oscilador com memória de forma é investigado. Verifica-se que o sistema pode responder caoticamente sob determinadas condições. É também apresentado um método, baseado na técnica dos Elementos Finitos, para a análise estática e dinâmica não-linear de estruturas reticuladas com memória de forma. Resultados de simulações numéricas ilustram a complexidade do comportamento destas estruturas. / [en] Motivated by recent developments in the field of intelligent structures and materials, the present work reports results from an investigation on the dynamical behavior of mechanical systems containing elements with shape memory. Initially, three phenomenologieal theories that attempt to describe shape memory and pseudoelastic effects in metallic alloys that undergo thermoelastic martensitic transfomations are reviewed. Two of these theories are used to model and helical spring. The dynamic response of an oscillator with shape memory spring is investigated. It is shown tlm the system may behave chaotically under certain conditions. A method based on the Finite Element techinique, which can be applied to model the non-linear static and dynamic behavior of adaptive trusses with shape memory elements is also presented. Results of numerical simulations illustrate the complex behavior of these structures.

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Submitted by FREDERIC CONRAD JANZEN null (fcjanzen@utfpr.edu.br) on 2016-11-13T01:59:49Z No. of bitstreams: 1 Positioning and vibration control of a flexible structure in slewing motion by applying Shape Memory Alloys.pdf: 10393447 bytes, checksum: 905f7c805c63133af1f576ad7ebbfd4b (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-11-17T18:09:27Z (GMT) No. of bitstreams: 1 janzen_fc_dr_bauru.pdf: 10393447 bytes, checksum: 905f7c805c63133af1f576ad7ebbfd4b (MD5) / Made available in DSpace on 2016-11-17T18:09:27Z (GMT). No. of bitstreams: 1 janzen_fc_dr_bauru.pdf: 10393447 bytes, checksum: 905f7c805c63133af1f576ad7ebbfd4b (MD5) Previous issue date: 2016-09-19 / Estruturas flexíveis com movimento de rastreamento tem sido encontradas com frequência cada vez maior em diversos tipos de aplicações, por serem mais eficientes do que suas concorrentes rígidas. O estudo desses sistemas é importante por conta das vibrações advindas da redução de massa das estruturas. Muitos trabalhos têm sido publicados apresentado técnicas de controle aplicadas na redução dos efeitos dessas vibrações. Vários trabalhos demonstram a aplicação de materiais inteligentes como atuadores para esse tipo de aplicação. Sendo assim, o presente trabalho apresenta uma proposta para o controle do posicionamento angular e da vibração de uma estrutura flexível em movimento de rastreamento. Para tal, atuadores compostos de um material inteligente conhecido como Liga com Memoria de Forma são empregados para o controle da vibração da estrutura flexível. Com relação ao controle, a técnica de controle conhecida como Equações de Ricatti Dependentes dos Estados (SDRE) é aplicada para o controle. Com o objetivo de analisar a dinâmica do sistema com o controle proposto considera-se a modelagem matemática do sistema e sua validação através do desenvolvido de um protótipo experimental. Simulações numéricas são realizadas para analisar a viabilidade do controle proposto e testes experimentais são realizados com a finalidade de validar o modelo teórico e a proposta de controle. / Flexible structures with slewing motion has been found with increasing frequency in various types of applications, because they are more efficient than their rigid competitors. The study of these systems is important because of the vibrations coming from the mass reduction of structures. Many works have been published presenting control techniques applied in reducing the effects of these vibrations. Several studies demonstrate the application of intelligent materials as actuators for this application. This paper presents a proposal for controlling the angular positioning and vibration of a flexible structure in slewing motion. For such compounds an intelligent actuator materials known as Shape Memory Alloy is employed to control the vibration of the flexible structure. To control the system, the control technique known as State Dependent Ricatti Equation (SDRE), is applied to the control. In order to analyse the dynamics of the system with the proposed control the mathematical modelling of the system is considered and its validation by developed an experimental prototype. Numerical simulations are carried out to analyse the viability of the control and experimental tests are performed in order to validate the theoretical model and the proposed control.

Thesis submitted in fulfilment of the requirements for the degree Magister Technologiae: Mechanical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2008 / The increasing requirement for light weight constructions and the unsatisfactory performances of traditional metals and conventional engineering materials, especially in their failure to positively respond to environmental stimuli, in a demanding environment have made the search for the development of alternative materials inevitable. Such alternative materials being sought, which are the so-called adaptive, multifunctional, smart or intelligent composites would facilitate the realization of some engineering applications that are simply difficult to achieve with the existing conventional materials. Composite materials have found increasing applications in construction, aerospace and automotive industries due to their good characteristics of light weight, improved strength, corrosion resistance, controlled anisotropic properties, and reduced manufacturing and maintenance costs. However, there is a growing demand to improve on composite materials to have “smart" capabilities so as to be able to sense, actuate and respond to the surrounding environment. Shape memory alloys (SMAs) are metallic alloys that can undergo martensitic phase transformations as a result of applied thermomechanical loads and are capable of recovering permanent strains when heated above a certain transformation temperature. SMAs possess sensing and actuating functions and have the potential to control the mechanical properties and responses of their hosts due to their inherent unique characteristics: shape memory effect (SME) and pseudoelasticity. When integrated into structural components, they perform sensing, diagnosing, actuating and repair or healing functions, thereby enhancing improved performance characteristics of their hosts. Amongst the commercially available SMAs, NiTi (Nickel-Titanium) alloys in forms of wires, ribbons, bars, particles and porous bulks are the most widely used because of their excellent mechanical properties and superior material characteristics. Embedding SMAs into composite materials can create smart or intelligent hybridized composites. This thesis details an investigation of the mechanical properties and behaviour of the hybridized composites formed by embedding NiTi SMA wires into 60D polyurethane. The composites were produced by the vacuum process of manufacturing. The properties of the implanted SMA wires were enhanced by ageing and pre-straining. Uniaxial tensile and four point bending tests were conducted to ascertain the significance of embedding SMA wires into the polyurethane host matrix. It was found that the embedded SMA results in an increasing in elastic modulus, tensile strength and bending stiffness. It was found that these improvements in the properties can not be sustained at high temperature owing to degradation of interfacial strength between the SMA and polyurethane as a result of the high recovery stress generated by the SMA upon activation. Some measures that can ameliorate the interfacial breakdown were suggested.