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La necesidad de refuerzo estructural en una infraestructura existente puede venir motivada por la aparición de nuevos condicionantes de uso o por la degradación de los materiales. Desde finales de los años sesenta, la técnica del refuerzo mediante la adhesión de platabandas metálicas se ha llevado a la práctica como alternativa a otros métodos de refuerzo tradicionales. Sin embargo, las platabandas metálicas presentan algunas desventajas, como son su peso y su posible corrosión por agentes atmosféricos, que pueden solventarse sustituyéndolas por laminados de polímeros reforzados con fibras (FRP). Estos materiales poseen relaciones resistencia/peso y rigidez/peso mayores que el acero, facilitando su colocación, reduciendo costes y plazos de ejecución.En numerosos estudios empíricos se observa como la aplicación de laminados encolados puede resultar en una rotura frágil que conduce al desprendimiento prematuro del refuerzo antes de alcanzar la carga última.El principal objetivo de este trabajo es el desarrollo de un método simple y efectivo para dimensionar y comprobar el refuerzo de estructuras existentes con laminados adheridos de tal forma que se eviten los modos prematuros de rotura que conducen al desprendimiento del laminado. Se ha dedicado especial atención a la transferencia de tensiones de laminado a hormigón que resulta el punto clave del correcto comportamiento de este tipo de refuerzo.En el Capítulo 2, tras una revisión histórica de las líneas de investigación existentes, experimentales y teóricas, se ha evaluado mediante una base de datos experimental la fiabilidad de los modelos teóricos existentes para pronosticar y prevenir los modos de rotura prematuros antes mencionados. Esta base de datos experimental incluye resultados de la literatura existente y de una campaña experimental llevada a cabo por el autor en el Laboratorio de Tecnología de Estructuras de la Universidad Politécnica de Cataluña.Para resolver las deficiencias de los modelos teóricos existentes, en el Capítulo 3, se ha aplicado la teoría de la Mecánica de Fractura No Lineal a un caso de corte puro para modelizar el comportamiento de la interfase y sus roturas prematuras. Se han obtenido las distribuciones de tensiones en la interfase y en el laminado junto a la fuerza máxima transferida en función de tres parámetros (energía de fractura, máxima tensión tangencial y deslizamiento asociado a dicha tensión).La formulación de un caso de corte puro se ha extendido a un caso general de una viga bajo cargas transversales en el Capítulo 4. Se ha estudiado la evolución del desprendimiento del laminado en dos casos específicos: un elemento entre dos fisuras contiguas, y un elemento entre el extremo del laminado y la siguiente fisura. Se han obtenido las distribuciones de tensiones para las distintas fases del proceso. Cabe mencionar que la fuerza transferida entre dos fisuras alcanza su máximo valor cuando la tensión tangencial máxima llega a la fisura menos cargada. En este instante, ya se puede haber iniciado o no la formación de una macrofisura. El elemento entre el extremo del laminado y la siguiente fisura es similar al caso de corte puro.Las distribuciones de tensiones presentadas en el Capítulo 4 nos ayudan a comprender el comportamiento de un elemento reforzado con laminados adheridos en su cara traccionada, sin embargo, resultan complejas en la práctica. En el Capítulo 5 se describe un nuevo método de dimensionamiento y verificación basado en la obtención de una relación entre el máximo cortante antes de que se produzca el desprendimiento prematuro del refuerzo y el momento aplicado. Esta relación está asociada a la fuerza máxima transferida entre fisuras. A partir de la predicción del valor máximo de cortante, se verifica el desprendimiento del extremo del laminado evaluando la fuerza transferida entre dicho punto y la siguiente fisura. Se ha verificado la fiabilidad de esta propuesta mediante la base de datos de ensayos a flexión.Finalmente, en el Capítulo 6 se resumen las principales conclusiones del trabajo presentado en esta tesis y se sugieren futuras líneas de investigación. / The strengthening of aging infrastructures is in most cases required because of the necessity for increased levels of service loads or because of the degradation of structural materials. The technique of strengthening by externally bonding steel plates has been in practice since the late 1960's. However, steel plates present some disadvantages in terms of weight and corrosion that can be solved by replacing them with fiber reinforced polymer (FRP) laminates. FRP laminates provide benefits such as high strength-to-weight and stiffness-to-weight ratios, corrosion resistance as well as reduced installation costs due to their easy-handling.Existing experimental work has shown that the application of externally bonded laminates can result in a catastrophic brittle failure in the form of a premature debonding of the laminate before reaching the design load.The main aim of this research has been the development of a simple effective method to design and verify the strengthening of an existing structure with an externally bonded plate while preventing the premature peeling failure that causes the laminate to debond. Special attention has been drawn on to transfer of stresses from laminate to concrete through the interface, which is the main key in the correct performance of externally reinforced concrete structures.After a historical overview of the existing experimental and theoretical lines of research, the suitability of using existing theoretical models to forecast and prevent peeling failures is evaluated in Chapter 2 by means of an experimental bending test database. This database includes results from the existing literature and results from an experimental program conducted by the author at the Structural Technology Laboratory of the Technical University of Catalonia.To solve the weaknesses of the existing theoretical models, in Chapter 3, Non-Linear Fracture Mechanics theory is applied in a pure shear case to model the interface behavior and its premature failures. The stress distributions, together with the maximum transferred force are obtained as a function of three model parameters (the fracture energy, the maximum shear stress and the sliding associated to this stress).The formulae of a pure shear specimen are then extended to a general case of a beam under transverse loads in Chapter 4. For this purpose, the evolution of the debonding process is studied for two specific cases: a beam element between two cracks, and a beam element between the laminate end and the nearest crack. The stress distributions are obtained for the different stages observed in the debonding process. A specific highlight observed was that the transferred force between cracks is at maximum when the maximum shear stress reaches the less-loaded crack. In this instance, a macrocrack may or may not have already initiated. Another point observed is related to the beam element between the laminate end and the nearest crack, which is similar to the pure shear specimen.The stress distributions derived in Chapter 4 allow us to understand the behavior of an externally reinforced element, but are awkward for design purposes. Chapter 5 describes both a new design and verification method based on a maximum shear force-bending moment relationship associated to the theoretical maximum transferred force between two consecutive cracks before peeling occurs. After calculating the predicted value for the maximum shear force from the peeling relationship, the developed method verifies the debonding at the laminate end by checking the transferred force between the laminate end and the first crack in the laminate. The reliability of this proposal is verified by means of the assembled bending test database.Finally, the main conclusions drawn from the work presented in this dissertation are summarized in Chapter 6. Future work and research lines are suggested as well.

This research focuses on developing new techniques and designs for highly con- trollable microactuating systems with large force-stroke outputs. A fixed-fixed mi- crobeam is the actuating element in the introduced techniques. Either buckling of a microbridge by thermal stress, lateral deflection of a microbridge by electro- magnetic force, or combined effects of both can be employed for microactuation. The proposed method here is MicroElectroThermoMagnetic Actuation (METMA), which uses the combined techniques of electrical or electro-thermal driving of a mi- crobridge in the presence of a magnetic field. The electrically controllable magnetic field actuates and controls the electrically or electrothermally driven microstruc- tures. METMA provides control with two electrical inputs, the currents driving the microbridge and the current driving the external magnetic field. This method enables a more controllable actuating system. Different designs of microactuators have been implemented by using MEMS Pro as the design software and MUMPs as the standard MEMS fabrication technology. In these designs, a variety of out-of- plane buckling or displacement of fixed-fixed microbeams have been developed and employed as the actuating elements. This paper also introduces a novel actuating technique for larger displacements that uses a two-layer buckling microbridge actu- ated by METMA. Heat transfer principles are applied to investigate temperature distribution in a microbeam, electrothermal heating, and the resulting thermoelas- tic effects. Furthermore, a method for driving microactuators by applying powerful electrical pulses is proposed. The integrated electromagnetic and electrothermal microactuation technique is also studied. A clamped-clamped microbeam carry- ing electrical current has been modeled and simulated in ANSYS. The simulations include electrothermal, thermoelastic, electromagnetic, and electrothermomagnetic effects. The contributions are highlighted, the results are discussed, the research and design limitations are reported, and future works are proposed.

This thesis develops strain and kinetic energy functions and a finite beam element useful for analyzing curved beams which go through large deflections, such as a hockey stick being swung and bent substantially as it hits the ice. The resulting beam model is demonstrated to be rotation invariant and capable of computing the correct strain energy and reaction forces for a specified deformation. A method is also described by which the model could be used to perform static or dynamic simulations of a beam.

Scanned proton beams offer the possibility to take full advantage of the dose deposition properties of proton beams, i.e. the limited range and sharp peak at the end of the range, the Bragg peak. By actively scanning the proton beam, laterally by scanning magnets and longitudinally by shifting the energy, the position of the Bragg peak can be controlled in all three dimensions, thereby enabling high dose delivery to the target volume only. A typical scanned proton beam line consists of a pair of scanning magnets to perform the lateral beam scanning and possibly a range shifter and a multi-leaf collimator (MLC). Part of this thesis deals with the development of control, supervision and verification methods for the scanned proton beam line at the The Svedberg laboratory in Uppsala, Sweden. Radiotherapy is preceded by treatment planning, where one of the main objectives is predicting the dose to the patient. The dose is calculated by a dose calculation engine and the accuracy of the results is of course dependent on the accuracy and sophistication of the transport and interaction models of the dose engine itself. But, for the dose distribution calculation to have any bearing on the reality, it needs to be started with relevant input in accordance with the beam that is emitted from the treatment machine. This input is provided by the beam model. As such, the beam model is the link between the reality (the treatment machine) and the treatment planning system. The beam model contains methods to characterise the treatment machine and provides the dose calculation with the reconstructed beam phase space, in some convenient representation. In order for a beam model to be applicable in a treatment planning system, its methods have to be general. In this thesis, a beam model for a scanned proton beam is developed. The beam model contains models and descriptions of the beam modifying elements of a scanned proton beam line. Based on a well-defined set of generally applicable characterisation measurements, ten beam model parameters are extracted, describing the basic properties of the beam, i.e. the energy spectrum, the radial and the angular distributions and the nominal direction. Optional beam modifying elements such as a range shifter and an MLC are modelled by dedicated Monte Carlo calculation algorithms. The algorithm that describes the MLC contains a parameterisation of collimator scatter, in which the rather complex phase space of collimator scattered protons has been parameterised by a set of analytical functions. Dose calculations based on the phase space reconstructed by the beam model are in good agreement with experimental data. This holds both for the dose distribution of the elementary pencil beam, reflecting the modelling of the basic properties of the scanned beam, as well as for complete calculations of collimated scanned fields.

Newbeam Sweden AB är ett ganska ungt företag som genom deras patent har börjat kunna pressa unika träkompositer i 3 dimensioner. Företaget ligger i startgroparna med sin första tillverkningslina som skall öppnas i Söderhamn, Hälsingland. De själva har satsat mycket mot byggnadsindustrin. Min uppgift i detta arbete har varit att undersöka andra marknader med deras profi lpressade träkompositer som grund. Inriktningen blev butiksinredningar som ett resultat av researcharbetet som gjordes. Intervjuer och undersökningar gav en bild av hur viktigt det är med användarvänlighet samt enkelhet och de två orden blev mitt motto arbetet igenom. Resultatet av detta kom att bli lite mer än bara butiksinredningar. / Newbeam Sweden AB is a fairly young company which with their new patent are able to press unique wood composite in 3 dimensions. The company are about to start thier fi rst manufacturing line in Söderhamn, Hälsingland. Their main target is to make components for house-constructions. My objective in this project has been to investigate other fi elds of interest with their 3 dimensional wood composite beams as buildingblocks. From the research that was made, a focus towards stores and their furnish equipment came to be the concentration. Interviews and investigations gave a good picture of how important it is to off er easy-to-use and simplicity in constructions. Theese words became my motto during this project. The result of my work came to be a little more than furnish equipment for stores.

The work describes the development of a reliable device for profiling anion beam in the intensity cross section. A sensor head consisting of a Faradaycup in combination with a Channel Electron Multiplier was designedand built together with electronics including power supply and front endelectronics. The design was chosen considering financial and long term lifeaspects. Testing, first calibration and error analysis were done using the ionbeam facilities where the unit is supposed to be installed permanently. Theprofiling system performed as designed and the profile of the ion beam couldbe measured reliably with an accuracy down to the femto ampere range.

Phased arrays eliminate the problems of mechanical steering by using fast and reliable electronic components for steering the main beam. Modeling and simulation of beam steering for 1D and 2D arrays is the aspect that is considered in this thesis. A 1D array with 4 elements and a 2D array with 16 elements are studied in the X-band (8-12 GHz). The RF front-end of a phased array radar is modeled by means of ADS Momentum (Advanced design system).

Some products share one or two modules and while developing these products, structural optimization with stiffness as the objective function can be a useful tool. There might be no or very little CAD-data available in the pre-development phase and it is not certain that existing designs can be, or is desirable to use as a reference. The main objective of this thesis is to establish an accurate and fast-to-use methodology which can be utilized while developing new cars. In this thesis, the Volvo products S40, V50 and C70 serve as a basis for this case study. All the models are beam structures and the masses of components are added as point and line masses. Several optimization analyses are performed on one or three products exposed to seven load cases. Additional analyses with shell elements, more simplified models and changed load case balance achieved by normalization of the different load case compliances are also studied to investigate how these factors influence the results. Analyses show that front crash to a great extent dominates the results while normalization increases the influence of the remaining load cases. Since front crash is dominating and the front area is shared in all products, the performance is remarkably similar when three products are optimized compared to separate analyses of one product. Analysis of models without added point or line masses gives a result which greatly differs from previous results and therefore shows that added masses are required. The methodology is applicable to develop products and detect new load paths through the car.