Permanent magnets are today widely used in electrical machines of all sorts. With their increase in popularity, the amount of research has increased as well. In the wind power project at Uppsala University permanent magnet synchronous generators have been studied for over a decade. However, a tool for studying demagnetization has not been available. This Ph.D. thesis covers the development of a simulation model in a commercial finite element method software capable of studying demagnetization. Further, the model is also capable of simulating the connected electrical circuit of the generator. The simulation model has continuously been developed throughout the project. The simulation model showed good agreement compared to experiment, see paper IV, and has in paper III and V successfully been utilized in case studies. The main focus of these case studies has been different types of short-circuit faults in the electrical system of the generator, at normal or at an elevated temperature. Paper I includes a case study with the latest version of the model capable of handling multiple short-circuits events, which was not possible in earlier versions of the simulation model. The influence of the electrical system on the working point ripple of the permanent magnets was evaluated in paper II. In paper III and VI, an evaluation study of the possibility of creating a generator with an interchangeable rotor is presented.  A Neodymium-Iron-Boron (Nd-Fe-B) rotor was exchanged for a ferrite rotor with the electrical properties almost maintained.

The overall goal of this research is to develop methods and algorithms to investigate the severity of Traumatic brain injury (TBI) and to estimate the intracranial pressure (ICP) level non-invasively. Brain x-ray computed tomography (CT) images and artificial intelligence methods are employed to estimate the level of ICP. Fully anisotropic complex wavelet transform features are proposed to extract directional textural features from brain images. Different feature selection and classification methods are tested to find the optimal feature vector and estimate the ICP using support vector regression. By using systematic feature extraction, selection and classification, promising results on ICP estimation are achieved. The results also indicate the reliability of the proposed algorithm. In the following, case-based finite element (FE) models are extracted from CT images using Matlab, Solidworks, and Ansys software tools. The ICP estimation obtained from image analysis is used as an input to the FE modeling to obtain stress/strain distribution over the tissue. Three in-plane modeling approaches are proposed to investigate the effect of ICP elevation on brain tissue stress/strain distribution. Moreover, the effect of intracranial bleeding on ICP elevation is studied in 2-D modeling. A mathematical relationship between the intracranial pressure and the maximum strain/stress over the brain tissue is obtained using linear regression method. In the following, a 3-D model is constructed using 3 slices of brain CT images. The effect of increased ICP on the tissue deformation is studied. The results show the proposed framework can accurately simulate the injury and provides an accurate ICP estimation non-invasively. The results from this study may be used as a base for developing a non-invasive procedure for evaluating ICP using FE methods.

The effects of lime treatment on the mechanical properties of soils are usually not accounted for in the design of geotechnical structures. As a result the potential of lime treatment has not been fully exploited. In this thesis, a comprehensive experimental program has been carried out to identity the key features of the mechanical behaviour of structured materials. The chemical modifications arising from lime treatment were quantified using thermal analysis methods. From these results a non-linear chemo-mechanical coupling was established between the concentration of cementitious compounds and the yield stress. Using these results, a new formulation to model the degradation of the structure at yield has been developed and implemented in a constitutive model for structured materials. This new model, developed in the framework of the Modified Cam Clay model, requires a limited number of additional parameters that all have a physical meaning and can all be determined from a single isotropic compression test. The model has proven to be successful in reproducing the key features of structured materials and for the modelling of the mechanical behaviour of lime treated specimens under various stress paths. Due to similarities in behaviour, it is shown that the formulation is also suitable for naturally structured soils. To account for a structured material in the design of geotechnical structures, a fully functional finite element program for elasto-plastic problems was developed including the pre- and post-processing of the results. A thorough validation has confirmed the good implementation of the finite element method and its suitability for the modelling of complex geometries involving structured materials.

Osseointegration is defined as the direct physical and practical relation between the living tissue and implant surface. Although, success rate of dental implants is high, implant failure occurs. Overloading implants from occlusal forces are known as one of the main reasons. In order to have successful implant, a dynamic balance must be provided between mechanical and biological elements (Isidor, Flemming 1996). Şimşek et al. reported bone quality, oral sanitation, host medical condition and biomechanical parameters as the main reasons for implants failure. Also, implant fixture micromotion and inappropriate stress in the bone implant interface is known as the potential reasons for early bone loss and implant failure (Şimşek, Barış 2006). Even so, implant position in jawbone, bone density; biomaterial properties of implant surface, treatment technique, loading history and patient clinical status are the influential factors in implant success (Brunski, J.B. 1999). Although there are many studies on stress distribution of implants in bone-implant interface, majority are limited to current implants in the market. However, current designs have been developed by marketing purposes rather than scientific considerations. Therefore, there is need to introduce and analyse new designs in order to optimize implant structure. Recent investigations have shown reliability of FEA method in simulating human jawbone situation. This research aims to develop a new dental implant with better life expectancies and introduce an optimized implant based on FEA stress analyses and experimental tests. Therefore, based on literature recommendations a series of new design factors are defined and analysed. In this study, a primary design is created in AutoCAD and yields to 3 different implants developed in SolidWorks. Branemark MK IV was selected as the bench model to play role of control group. Then, CT-scan images of human jawbone are imported to MIMICS to create a host bone model. Implant and jawbone models are assembled in 3-Matic and exported to Abaqus for final analyses. A series of loadings are defined to examine implant performance in different conditions. Branemark and C-3 implants are manufactured from Titanium for experimental analyses. Mechanical tests on sawbone foam blocks and cadavers are targeted to portray realistic performance. This research demonstrates C-3 model as the optimized dental implant, which presents a new design profile and better performance in low bone densities. The FEA and experimental results validate the benefit of the new design compare to the conventional ones. Furthermore, results can provide a basis for future designers to develop further optimizations.

Les travaux de thèse portent sur l'évaluation et la robustesse des stratégies adaptées pour la simulation de grandes structures avec non-linéarités non équitablement réparties, tels le flambage local, et des non-linéarités globales dans les structures aéronautiques. La stratégie dite de « relocalisation non-linéaire » permet l'introduction de schémas de résolution non-linéaire par sous-structure au sein des méthodes de décomposition de domaine classiques.Dans un premier temps, les performances et la robustesse de la méthode sont présentées sur des exemples de structures représentatives des cas industriels. Dans un second temps, la stratégie est complètement parallélisée et des études de « speed-up » et de « extensibilité » sont menées. Enfin, la méthode est testée sur des structures réalistes et de grandes tailles. / The thesis work focus on the evaluation and the robustness of adapted strategies for the simulation of large structures with not equitably distributed nonlinearities, like local buckling, and global nonlinearities on aeronautical structures. The nonlinear relocalization strategy allows the introduction of nonlinear solving schemes in the sub-structures of the classical domain decomposition methods.At a first step, the performances and the robustness of the method are analysed on academic examples. Then, the strategy is parallelized and studies of speed-up and extensibility are carried out. Finally, the method is tested on larger and more realistic structures.

M.Ing. / Optical fibre Bragg gratings are a periodic variation of the refractive index in the core of an optical fibre andmay be formed by exposure to intense UV laser light under specific conditions. Light at a certain wavelength, called the Bragg wavelength, is reflected back when illuminating the grating with a light source. Bragg gratings can relatively easily be employed as strain and temperature sensors, but have small sensitivity for pressure. Special transducers are required to increase the sensitivity. A pressure sensor was manufactured by coating a fibre Bragg grating with a polymer. The polymer coating converts transverse pressure into longitudinal strain through the Poisson effect inside the polymer coating. This thesis investigates the sensitivity of themanufactured Bragg grating pressure sensor, by using the method of finite element analysis. An account of the experimental setup, whereby the Bragg grating is written with a frequency tripled Nd:YAG laser, is given. The process whereby the fibre is coated with the polymer is described. The sensor is characterized through experimental results and a comparison is made between theoretical and experimental results. Uses for this sensor and ways with which the sensitivity may be increased are suggested as future work.

A chassis is known as the carrying unit of an automobile, like the engine, transmission shaft and other parts are mounted on it. Ladder chassis has longitudinal rails which are connected along the length with crossmembers through welding or mechanical fasteners. Rectangular box section is chosen for the longitudinal rails of ladder chassis. Design modifications are done in HyperMesh to improve torsional and bending stiffness of the chassis designed in steel and CFRP. Adding of the X- bracing cross-member and ribs are few of the techniques used to provide strength to chassis. This thesis aims to produce a light-weight chassis. A combination chassis of both steel and CFRP components is created by replacing heavy steel cross-members with CFRP cross-members, which resulted in the reduction of weight by 14.6%. Crash analysis is performed to all the chassis using Radioss. Depending on the result obtained from crash analysis and values of torsional and bending stiffness, the combination chassis is selected. Thickness optimization is performed to the combination chassis. It is observed that 7.91% of weight is further reduced in the combination chassis.

Underground mining equipment is required by the Mine Safety and Health Administration to have certified overhead protective structure, referred to here as a canopy. By reviewing previous works in the area of protective canopies and utilizing their findings to

The atomic force microscopy (AFM) has been widely used for the investigation of the surface topography and high precision force measurements at the nano-scale. Researchers have utilized AFM to quantify the viscosity of the cell membrane in the vertical direction, which is a primary indicator of a cell's functionality and health condition. A modified lateral force microscopy (LFM) to quantify viscosity through lateral force measurements applied on the sidewall of cell membranes. The resulting twist of the cantilever in mLFM is induced by the contact between sidewalls of the tip and features on the sample. However, the measurement sensitivity of the mLFM requires improvement. This thesis focused on optimizing probe geometries and materials to improve the measurement sensitivity. <div>Probes (cantilevers and tips) with different geometries and materials properties were proposed and their deformations in the mLFM force measurement were studied. The force measurement process, in which the tip contacted the sidewall of control samples, including a hard sample and a soft sample, was modeled by finite element analysis (FEA). This study calculated torsional spring constants and measurement sensitivities according to the data produced from FEA. The impact of various geometric parameters on the torsional spring constant and measurement sensitivity were presented and discussed. The optimal probe configuration and material for measurement sensitivity was found from the parameters tested in this research. For the hard sample, the cantilever with a "T-shape" cross section and a tetrahedral tip made from graphite had optimum measurement sensitivity. For the soft sample, the cantilever with a "T-shape" cross section and a conical tip with a 600nm-radius sphere tip apex had the optimum measurement sensitivity. The reason for the difference in optimum probe combination for hard and soft sample was that the measurement sensitivity for hard sample was more susceptible to change in lever arm distance and measurement sensitivity for soft sample was more susceptible to the change in tip radius. The measurement sensitivity has been improved significantly on both hard sample and soft sample compared to a DNP V-shaped probe. </div>

<p></p><p>Granular material blending plays an important role in many industries ranging from those that manufacture pharmaceuticals to those producing agrochemicals. The ability to create homogeneous powder blends can be critical to the final product quality. For example, insufficient blending of a pharmaceutical formulation may have serious consequences on product efficacy and safety. Unfortunately, tools for quantitatively predicting particulate blending processes are lacking. Most often, parameters that produce an acceptable degree of blending are determined empirically.</p> <p> </p> <p>The objective of this work was to develop a validated model for predicting the magnitude and rate of granular material mixing and segregation for binary mixtures of granular material in systems of industrial interest. The model utilizes finite element method simulations to determine the bulk-level granular velocity field, which is then combined with particle-level diffusion and segregation correlations using the advection-diffusion-segregation equation. </p> <p> </p> <p>An important factor to the success of the finite element method simulation used in the current work is the material constitutive model used to represent the granular flow behavior. In this work, the Mohr-Coulomb elastoplastic (MCEP) model was used. The MCEP model parameters were calibrated both numerically and experimentally and the procedure is described in the current work. Additionally, the particle-level diffusion and segregation correlations are important to the accurate prediction of mixing and segregation rates. The current work derived the diffusion and segregation correlations from published literature and determined a methodology for obtaining the particle diffusion and segregation parameters from experiments.</p> <p> </p> <p>The utility of this modelling approach is demonstrated by predicting mixing patterns in a rotating drum and Tote blender as well as segregation patterns in a rotating drum and during the discharge of conical hoppers. Indeed, a significant advantage of the current modeling approach compared to previously published models is that arbitrary system geometries can be modeled.</p> <p> </p> <p>The model predictions were compared with both DEM simulation and experiment results. The model is able to quantitatively predict the magnitude and rate of powder mixing and segregation in two- and three-dimensional geometries and is computationally faster than DEM simulations. Since the numerical approach does not directly model individual particles, this new modeling approach is well suited for predicting mixing and segregation in large industrial-scale systems.</p><br><p></p>