The common 3-point safety belt usually has some anchor points on the car body. However, it is also possible to mount all anchor points on the seat structure. In general, different studies show some advantages with seat integrated safety belts. Thus, further investigations are motivated. One safety advantage appears in the case of so-called small overlap crashes. Also, the ride-down distance of the occupant may be increased by allowing controlled energy absorbing deformation of the seat structure. Further, methods that can be used to minimize the weight of seat structures with integrated safety belts are of interest. A complement to full scale crash tests is the use of numerical models and numerical simulation, typically finite element (FE) analysis. Research and development of numerical models are constantly improved. In general, any type of numerical model needs to be evaluated to physical tests in order to make it behave as realistic as possible. The purpose of the present thesis was to study seat structures with integrated safety belts with a design that may intentionally deform and absorb energy during a crash. The approach was to use numerical models and numerical simulation and to investigate both biomechanical and mechanical responses. The aim is to create a basis for future research in the design of seat structures with integrated safety belts. In Paper A and B, parametric studies comparing integrated 3- and 4-point safety belt configurations relative to common 3-point configurations are presented. A number of mechanical parameters were varied. Biomechanical responses of the Hybrid III (HIII) FE-dummy model used as occupant were studied. In Paper C, the creation and evaluation of a human FE-model of a 50th percentile male is presented. The evaluation was made to results from studies with post mortem human subjects (PMHS). In Paper D, a conceptual methodology for mass minimization of a property based model (PBM) of a seat structure with an integrated 3-point safety belt configuration and with a HIII FE-dummy model used as occupant is presented. Both mechanical and biomechanical constraints were used as well as different start values of the design variables. In Paper E, the evaluation of FE-models of simplified seat structures with integrated 3-point safety belt configurations to a number of full scale experiments in the form of sled tests with a HIII crash test dummy used as occupant is presented. The studies in Paper A and B reveals that with an adequate combination of mechanical properties of the seat structure it should be possible to achieve equal or lower biomechanical responses of the occupant with a seat integrated safety belt configuration compared to a common. The seat integrated 4-point configurations in these studies performed poorer than the corresponding 3-point in general. An important issue is that belt- webbing distribution between lap and torso belt parts is allowed. The study in Paper C showed that the created and evaluated human FE-model could be used to further explore injury producing mechanisms. However, in order to achieve a fully evaluated human FE-model there is a need for both further development and more reference tests with PMHS. In Paper D, the study showed that the presented methodology may be used in a concept phase of a design process. The optimization runs with different start values of the design variables found a number of different local minima instead of one global minimum. The dynamics of the system was highly non-linear. To find an optimal combination of mechanical properties and biomechanical responses, a compromise appears to be needed. The evaluated FE-model in Paper E may be used in simulations that consider both biomechanical and mechanical responses. The majority of the simulated responses showed good agreement with or slightly underestimated the experimental responses. Some issues of the FE-model suggest areas for further development. The FE-model could be used as a base for further studies. / Godkänd; 2008; 20080404 (ysko)

Denna rapport skall ses som en genomförbarhetsstudie för ett 4.5kW kraftaggregat som är avsett att operera i mycket stränga industriella miljöer. På grund av detta är hela aggregatets inre volym tätat från yttre åverkan och problemen aggregatet utsätts för är alltså både mekanisk påverkan i form av vibrationer och chock samt termisk påfrestning då kylning via insugningsluft är uteslutet. Lösningen för detta var att dimensionera och fixera mekaniken på ett tillfredställande sätt och även att kyla aggregatets alla effektbärande komponenter via vätskekylning i kombination med intern temperaturfördelning med en eller två cirkulationsfläktar. Resultatet blev principerna för ett gediget kraftaggregat som är ytterst motståndskraftig mot vibrationer och inkluderar därmed ett kylningsförfarande som kan motstå de mycket stränga temperaturstegringarna aggregatet kan tänkas utsättas för. / This report could be summarized as a feasibility study for a 4.5kW power supply which shall operate in a very harsh industrial environment. All internal components of the power supply are sealed from external damage because of this fact. The problem the power supply has to endure are both mechanical in form of vibrations and shock but also thermal since external intakes for a standard “fan cooling” solution is impossible. The solution was to scale the dimensions and fix the construct in a way that would prevent this type of mechanical damage and also use a fluid cooling solution from an external source where the cooled air inside will circulate thanks to a couple of internal fans. The result is a sturdy power supply design resistant to vibrations and with a cooling solution that can withstand the very harsh temperature situations this construct could be exposed to. / Termisk och mekanisk idégenerering med hjälp av datorsimuleringar

Membrane structures are commonly used in many fields. The studies of these structures are of increasing interest. The projects in this thesis focus on the evaluations of equilibrium states for pressurized membranes under different problem settings, using finite element methods, and the corresponding instability behaviors. The first part of the current work discusses the instability behavior of a thin, planar, circular and initially horizontal membrane subjected to downwards or upwards fluid pressure. The membrane structures exhibit large deformations under pressure. The method for evaluating fluid pressure from gravity was developed in finite element context, and used in numerical simulations. Limit and bifurcation points have been detected for different loading parameters and conditions. The effects on instabilities of parameters, the initial states of the membrane, and the chosen mesh are discussed. The second part of the current work discusses instability behavior of a thin, spherical and closed membrane containing gas and fluid, when placed on a horizontal rigid and non-friction plane. A multi-parametric loading is described. By adding practically relevant controlling equations, different classes of equilibrium paths were followed using a generalized path following algorithm. Stability conclusions were made, according to the considered load parameters and the constraints. A generalized eigenvalue analysis was used to evaluate the stability behavior including the constraint effects. Fold line evaluations were performed to analyze the parametric dependence. A solution surface approach is used to visualize the mechanical response under this multi-parametric setting. The third part of the current work focuses on instability response of a truncated sphere, containing gas and fluid, and in contact with two vertical rigid and non-friction planes. Different penalty formulations were used and compared. The effects of contact implementations on instability behaviors were investigated. Bifurcation points induced by contacts have been observed. Multi-parametric problems were defined, and generalized paths were followed. The multi-parametric stability was evaluated using generalized eigenvalue analysis, based on the mass and total differential matrices. The effects of augmenting equations on bifurcation points and limit points are discussed. The fourth part of the current work analyses the instability response of a truncated sphere, completely filled with fluid, placed on a horizontal plane and spinning around the vertical axis. The loads from fluid pressure and the constraints, e.g., fluid volume, were formulated to generate a symmetric differential matrix. Several mesh patterns with different symmetries were used to simulate the model, and the obtained results are compared. Various problem settings were considered, and generalized paths were followed. The effects of symmetry aspects of the chosen meshes on instability behaviors are discussed, as are the effects of parameters. / <p>QC 20170616</p>

No description available.

There is a strongly increasing request of measuring systems for mechanical properties studies, for example in the paper industry. Paper research is today not only concentrated to flock studies, weight and quality controls of the paper but also focussing of mechanical behaviours in the fibre scale. For this purpose, an optical metrology system for measurements of mechanical response in the µm-range of loaded sub-mm objects is developed, but the system could also be used for materials like polymer composites, wood or steel. The system is full-field, non-touching and all-electronic. The main components in the system are a stereomicroscope and a speckle correlation technique called digital speckle photography. Either a random structure pattern exists naturally on the sample or a dot pattern must be attached on its surface. Using white light illumination, 2-D and 3-D deformation fields as well as velocity fields can be measured. The standard deviations are about 60 nm in plane and about 170 nm out of plane, depending on the magnification and quality of the pattern. Information of the topography of the sample is provided in the calibration routine for 3-D measurements. By using laser illumination, measurements of microstructural changes on the object surface are possible through a technique called laser speckle decorrelation. Examples of measurements of micro-flow, 3D deformations and microstructural changes in printing paper are given in this thesis. / Godkänd; 2002; 20070222 (ysko)

A method to study the response in materials exposed to high energy laser pulses has been developed in this thesis. The method is based on focused and defocused Speckle Correlation and uses an illumination cw laser and digital camera to acquire images of speckle patterns. These images were captured using a CCD camera before, during and after the laser drilling processing and were saved in a computer. All image processing was performed after the drilling process has been finished. By using this method the size of the affected zone, in-plane strain, surface tilt and surface deformations can be quantified with the temporal resolution limited by the frequency of the camera being used. This thesis comprises three papers. One conference paper was presented at the International Conference on Laser-Matter Interaction in St.Petersburg 2003, and two papers were submitted to Applied Optics. Results are shown from single shot interaction on sheets of Al2O3 and stainless steel as well as responses in sheets of copper and silver during percussion hole drilling. The results obtained during processing are also compared with SEM images. It is concluded that the method gives valuable information about the drilling process and that it is a robust and highly sensitive alternative to Interferometry for the study of laser-matter interaction processes. / Godkänd; 2004; 20070128 (ysko)

The welding process introduces residual stress originating from the heating, melting and cooling of the material. From the point of view of fatigue and stress corrosion cracking, the weld residual stress perpendicular to the weld axis is of particular interest. When qualifying weld parameters for welds in large cylinders having a ratio of radius to plate thickness larger than say approximately 100; reference to plane plates are often made for the sake of simplicity. However, the weld residual stress perpendicular to the weld axis is severely underestimated in the plane plate compared with the cylindrical structure. This observation is especially pronounced in connection with preheating. The source of the differences is probably due to the radial constraint of the cylinder, compared with that of a plane plate. A plane test specimen will underestimate the weld residual stress perpendicular to the weld axis in a cylinder, even if the radius of the cylinder is very large. However, a test specimen for an 8 m diameter cylinder with a plate thickness of 35 mm needs only to have a segment width of approximately 1.3 m to reflect the stress in the real structure. The weld residual stress perpendicular to the weld axis in the vicinity of the weld toe is governed by the depositing of the weld bead adjacent to the weld toe, neglecting the accumulated strain from the previous deposited weld beads in the multi-pass joint weld. Introducing tensile straining perpendicular to the weld axis during the entire welding procedure reduces the weld-induced residual stress after completed welding. The plastic zone of the weld area will be subjected to compressive strain after completed welding, which in turn will reduce the weld residual stress. This can be achieved by cooling the weld area, which in this case is not recommended since the material is sensitive to hydrogen cracking, or by pre-stretching or modifying the locations for preheating, all aimed to impose a tensile axial straining around the weld area during the entire welding process. / Godkänd; 2004; 20070131 (ysko)

The ever-growing demand for renewable energy leads to an increased need for innovation in the green energy sector. One of the available alternatives, wind power, have seen a global increase in usage with few signs of slowing down. To increase the efficiency of individual turbines, correct placement is crucial. One technology that uses sound to find optimal locations for wind turbines is Sonic Detection and Ranging, SODAR. AQ system manufacture and deliver SODAR-systems internationally. The size of the system created by AQs limit the locations which the system can measure wind. Occasionally this forces measurement to be made away from the location in question which potentially reduce the efficiency of the future wind turbine. This study aims to create a concept for a smaller version of the SODAR-system manufactured by AQs. A smaller system would allow wind measurement in more remote, hard to reach locations which in turn would increase precision of the measurements and potentially efficiency of wind turbines.   Tools from Ulrich &amp; Eppingers product development process was used to generate, screen, and evaluate concepts throughout the study. By changing the geometry and positioning of individual components in the system the height was reduced by 49,7% and width by 32,8%. An even smaller concept could be presented if more focus was put on the base of the product. Many factors that could impact the function of the product have been ignored in this study. Based on the specifications put up for this project the concept could theoretically perform as the original AQ510. Considering that relevant factors have been ignored, the function of the concept cannot be guaranteed. The tools and methods used in the product development process facilitated the development and made it possible to present a concept within the time frame. The conclusion is that, based on the specifications presented, the concept reached the goals put up for the project but to be able to guarantee the performance of the concept, measurements and tests are needed.

The main objective of the work presented in this Licentiate thesis is to investigate and model the cyclic behaviour of an additively manufactured ductile nickel-based superalloy, with special emphasis on modelling the stabilised material behaviour, which is of interest for fatigue life predictions. Cyclic fatigue tests at different temperatures have been performed to investigate the cyclic mechanical behaviour of the material, where specimens built in different orientations have been used to also study the anisotropic behaviour of the material. Based on the tests, a constitutive description has progressively been developed and implemented in a finite element context that incorporates the anisotropic behaviour under both elastic and inelastic deformations. In addition, the room temperature crack initiation behaviour has been studied and modelled. This thesis is divided into two parts. The first part gives an introduction and background to the research, while the second part consists of three included papers. / Det huvudsakliga målet med arbetet som presenteras i denna avhandling har varit att studera och modellera det cykliska beteendet hos en additivt tillverkad duktil nickelbaserad superlegering, med fokus på att modellera det stabiliserade materialbeteendet, vilket är av intresse vid livslängdprediktering. Cykliska utmattningsprov vid olika temperaturer har utförts för att studera det cykliska beteendet hos materialet, där provstavar byggda i olika riktningar har använts för att studera materialets anisotropi. Baserat på proven har en konstitutiv beskrivning av material progressivt utvecklats och implementerats i ett finita element-verktyg, där modellen tar hänsyn till det anisotropa materialbeteendet för både elastiska och plastiska deformationer. En modell för prediktering av sprickinitiering vid rumstemperatur har också tagits fram. Denna avhandling består av två delar. Den första delen ger en introduktion samt bakgrund till forskningen, medan den andra delen består av tre inkluderade artiklar. / <p>Ytterligare forskningsfinansiär: Siemens Industrial Turbomachinery AB</p>

The dynamics and wear of non-linear impact oscillators, comprising a single-degree of freedom system as well as continuous beam systems are analysed. The considered beams are of cantilever type with the lateral motion of the free end constrained by elastic supports. They are modelled as Bernoulli beams with Rayleigh damping. A finite-element method is used for discretisation in space and Newmark's method for time integration. Wear is quantified using the work-rate concept. The model calculations are compared with measurements of contact forces and displacements made on a loosely supported nuclear fuel rod span subject to both harmonic and random excitation. Details of the vibro-impact dynamics in the time domain are well reproduced in the digital simulations. Work-rates computed from measured and simulated quantities are also in good agreement. Furthermore, the dynamics of vibro-impacts are characterised through global and local stability and bifurcation analysis. Global analysis is made by extensive time integration for both harmonic and stochastic excitation. The local analysis is made by way of a Poincaré mapping method relating the states at subsequent impacts at the elastic supports for harmonically excited systems. The domains of stability are mapped out and the work-rate at stable periodic orbits is examined. / Godkänd; 2001; 20070225 (ysko)