Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: thermomechanical, SMAs, NiTiNOL, ACES, OEH. Includes bibliographical references.

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006. / Gall, Kenneth, Committee Member ; Leon, Roberto, Committee Member ; Kurtis, Kimberly, Committee Member ; Jacobs, Laurence, Committee Member ; DesRoches, Reginald, Committee Chair.

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xi, 87 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 86-87).

Thesis (DTech (Mechanical Engineering))--Peninsula Technikon, 2004. / Engineers and Technologists have always been identified as those individuals that put into practice the theories developed by scientists and physicists to enhance the lives of human beings. In the same spirit as those that came before, this thesis describes the development of a computational engineering tool that will aid Engineers and Technologists to design smart or intelligent structures comprising of NiTi shape memory alloy rods for actuation purposes. The design of smart actuators consisting of NiTi shape memory alloy structural members will be beneficial to industries where light weight, compactness, reliability and failure tolerance is of utmost importance. This is mainly due to the unique material responses exhibited by this smart material. The shape memory effect, one of these material responses consists out of two stages: a low temperature load induced phase transformation causing a macroscopic deformation (either extension, contraction, etc.) also known as quasi-plasticity; and a high temperature phase transformation that erases the low temperature macroscopic deformation and reverts the material to some predefined geometry. When designing actuators consisting of this smart material, the quasi-plastic material response produces the actuation stroke while the high temperature phase transformation produces the actuation force. The successful engineering design of smart structures and devices particularly suited for applications where they operate in a capacity, as actuators harnessing the shape memory effect are dependent on a few important factors. These include the engineers familiarity with the type of smart material used, the availability of sound experimental data pertaining to the complex material responses exhibited by the smart material, the engineers level of proficiency with existing constitutive models available to simulates these material responses, and the engineers knowledge of simulation tools consisting of a suitable control algorithm fo~ the modeling of not only the device or structure itself but also the actuator involved in the design.

No description available.

Fiber optic sensors have been utilized as corrosion sensors by depositing metal coatings to the surface of the sensors. Three types of fiber optic sensors were investigated as candidates for corrosion detection: the extrinsic Fabry-Perot interferometer (EFPI), the absolute extrinsic Fabry-Perot interferometer (AEFPI), and the long period grating (LPG) fiber optic sensor. The corrosion monitoring technique used with the EFPI and AEFPI sensors exploits the ability of a thick coating of metal to maintain strain information in fiber optic strain sensors. The sensors are placed under tensile stress, and while in the resulting strained position, a thick coating of metal is applied. Due to an increase in the quantity of material, the sensor does not return to its original position upon release, and strain is maintained within the sensor element. As the metal thickness decreases due to corrosion, this residual strain is released, providing the sensing mechanism for corrosion detection. LPG fiber optic sensors have demonstrated their ability as bandstop filters, by coupling the fundamental guided mode to circularly symmetric cladding modes. The cladding modes are extremely lossy due to the fiber jacket and bending along the fiber. Losses at discrete wavelengths can be monitored to determine the onset and progress of metal corrosion. Background theory and experimental results are discussed and reported for EFPI, AEFPI, and LPG fiber optic corrosion sensors. The study is preceded with an overview of different corrosion sensor designs and methods which are used in the area of non-destructive evaluation. / Master of Science

A computational model is presented which predicts the force, stroke, and energy needed to overcome aerodynamic loads encountered by morphing wings during aircraft maneuvers. This low-cost model generates wing section shapes needed to follow a desired flight path, computes the resulting aerodynamic forces using a unique combination of conformal mapping and the vortex panel method, computes the longitudinal motion of the simulated aircraft, and closes the loop with a zero-error control law. The aerodynamic force prediction method has been verified against two more expensive codes. This overall model will be used to predict the performance of morphing wings and the requirements for the active material actuators in the wings. / Master of Science

Yes / Engineered Cementitious Composites (ECC) is a material which possesses advanced self-healing properties. Although the self-healing performance of ECC has been revealed in numerous studies, only small-scale, laboratory-size specimens have been used to assess it under fixed laboratory conditions and curing techniques. In order to evaluate the effect of intrinsic self-healing ability of ECC on the properties of structural-size, large-scale reinforced-beam members, specimens with four different shear span to effective depth (a/d) ratios, ranging from 1 to 4, were prepared to evaluate the effects of shear and flexural deformation. To ensure a realistic assessment, beams were cured using wet burlap, similar to on-site curing. Each beam was tested for mechanical properties including load-carrying capacity, deflection capacity, ductility ratio, yield stiffness, energy absorption capacity, and the influence of self-healing, by comparing types of failure and cracking. Self-healed test beams showed higher strength, energy absorption capacity and ductility ratio than damaged test beams. In test beams with an a/d ratio of 4 in which flexural behavior was prominent, self-healing application was highly successful; the strength, energy absorption capacity and ductility ratios of these beams achieved the level of undamaged beams. In addition, flexural cracks healed better, helping recover the properties of beams with predominantly flexural cracks rather than shear cracks. / The authors gratefully acknowledge the financial assistance of the Scientific and Technical Research Council (TUBITAK) of Turkey provided under Project: MAG-112M876 and the Turkish Academy of Sciences, Young Scientist Award program. The second author would also like to acknowledge the financial support of TÜBITAK for the 2219 Scholarship.

Doctor of Philosophy / Department of Chemistry / Christopher T. Culbertson / During the last five years, great advancements in microfluidics have been achieved with the development of “sample-in-answer-out” systems. Such systems have begun to realize the true potential of analytical miniaturization since the concept of the “micro-Total Analysis System” was first envisioned. These systems are characterized by the elegant integration of multiple fluid-handling channel architectures that enable serial execution of sample preparation, separation and detection techniques on a single device. While miniaturization and portability are often identified as key advantages for microfluidics, these highly integrated systems are heavily reliant upon large off-chip equipment, i.e. the microchip is often tethered to the laboratory via multiple syringe pumps, vacuum pumps, solenoid valves, gas cylinders and high voltage power supplies. In this dissertation, a procedure for the facile integration of dielectric elastomer (DE) actuators (called IDEAs) onto microfluidic devices is described. Poly(dimethylsiloxane) (PDMS) is commonly used as a microchip substrate because it is cheap and easy to fabricate, mechanically robust and optically transparent. The operation of an IDEA exploits the ability of PDMS to behave as a smart material and deform in the presence of an electric field. In Chapter 2, the fabrication of IDEA units on a standard microchip electrophoresis device is described. IDEA-derived injections were used to evaluate the physical performance of this novel actuator configuration. In Chapter 3, the analytical merits of IDEA-derived injections were evaluated. Sampling bias caused by electokinetic injection techniques has been problematic for conventional microchip electrophoresis systems due to the lack of fluid access. The hydrodynamic injections created by IDEA operation were found to be highly reproducible, efficient, and possess a negligible degree of sampling bias. In Chapter 4, the spatial characteristics of microchannel deformation due to IDEA actuation have been investigated using fluorescence microscopy. It was determined that the DE compresses more along the edge of the channel than in the middle of the channel. This information can be used to design a new generation of more efficient IDEAs.

Orientador: João Antonio Pereira / Banca: Luiz de Paula do Nascimento / Banca: Roberto Gil Annes da Silva / Resumo: Esse trabalho discute o uso dos materiais piezelétricos, mais especificamente, o Polyvinylidene Fluoride (PVDF) e o Lead Zirconate Titatane (PZT) na análise modal experimental (AME) de estruturas mecânicas. Materiais piezelétricos, também chamados de materiais inteligentes, têm se consolidado como uma nova tecnologia que mostra um grande potencial de aplicação em diferentes áreas da engenharia. Esse tipo de material exibe um acoplamento entre multi-domínios físicos, como por exemplo o acoplamento eletro-mecânico, o térmo-magnético, etc. O acoplamento eletro-mecânico produz um deslocamento elétrico quando o material é sujeito a uma tensão mecânica (efeito direto) e um deformação mecânica quando esse material é submetido a um campo elétrico (efeito inverso). Assim, principalmente por conta desses efeitos, seu uso no campo da análise modal experimental torna-se uma interessante questão a ser investigada. A incorporação de novas tecnologias nos testes estruturais pode agregar novos conhecimentos e avanços tanto na análise modal baseada na relação entrada-saída da estrutura, quanto na mais recente técnica, a análise modal baseada apenas na resposta das mesmas. Os conceitos teóricos para o desenvolvimento são apresentados e discutidos neste trabalho, onde é mostrada a análise modal de uma viga utilizando tanto sensores e atuadores convencionais quanto os produzidos com materiais inteligentes. Os testes de análise modal da viga foram feitos utilizando diferentes combinações de sensores e atuadores e isso pode mostrar as diferenças da estimativa de modos utilizando materiais piezelétricos. Também é apresentada a formulação da relação entre os modos em deslocamento e os modos com diferença de inclinação obtidos com materiais piezelétricos e, finalmente, uma comparação dos resultados obtidos pelas diferentes técnicas. Os testes apresentados mostram... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work discusses the use of piezoelectric materials, more specifically, Polyvinylidene Fluoride (PVDF) and Lead Zirconate Titanate (PZT) for experimental modal analysis (EMA) of mechanical structures. Piezoelectric materials also called smart materials have becoming a consolidated new technology that shows a large potential of application for different engineering areas. These materials exhibit a multi physics domain field coupling like mechanical and electrical coupling domains, thermal and magnetic coupling and etc. The electro-mechanical coupling domains of the material produces an electric displacement when the material is subject to a mechanical stress (direct-effect) and a mechanical strain when the material is submitted to an electric field (inverse effect). So, mainly due to these effects, the use in the experimental modal analysis field appears to be an interesting issue to be investigated. The incorporation of this new technology in the structural tests might aggregate new acknowledgments and advances in the well consolidated input-output based modal analysis techniques as well as in the more recent output only-based modal analysis. This work aims to present some contribution in this area by using piezoelectric sensors, instead of the conventional ones like accelerometers for modal analysis of mechanical structures. The theoretical concepts and background for the developing of the work are presented and discussed, it is also presented the modal analysis of a beam like structure using conventional sensors/actuators and piezoelectric materials. The modal analysis tests of the beam are conducted using different kinds of sensors/actuator and they give some insight of the difference of the estimated modes shapes by using piezoelectric materials. It is also presented a formulation that shows the relation between... (Complete abstract click electronic access below) / Mestre