Abdominal aortic aneurysms (AAA) occurs due to local enlargement of the abdominal aorta and affects about 1-2 % of the elderly Swedish population. At admission, AAA patients receive a Computed Tomography-Angiography (CT-A) scanning, and later they are followed-up by 2D ultrasound examinations. There is a need to know if an adequate geometry can be constructed from the baseline CT-A scan and follow-up 2D ultrasounds. To test our hypothesis only CT-A images have been used from six patients and hypothetical ultrasound cross-sections (HUCS) were extracted from the follow-up CT-A scans. The baseline AAA surface was expanded in a mechanical model by applying pressure inside of it until it reached the HUCS. The obtained morphed geometries were then compared with the CT-A-based geometries. The discrepancy between them were calculated by distance measurements. Also, the rupture risk indicators volumes and stresses were compared. Finally, a sensitivity analysis studied the effect of HUCS positioning on the volumes and stresses. The results show that an adequate geometry can be constructed by the investigated concept of morphing. The average distances between the morphed and CT-A-based geometries are 2-4 mm. The average volume difference for the six patients are between 3.8-16.2 %. The wall stress for the morphed and CT-A-based geometries are close only for the first follow-up. / Bukaortaaneurysm (AAA) uppstår på grund av lokal förstoring av bukaortan och drabbar 1-2 % av den äldre svenska befolkningen. Vid antagning får bukaortaaneurysm-patienterna en datortomografscanning (CT-A) och senare påföljs av 2D ultraljudsscanningar. Det finns ett behov att veta om en adekvat geometri kan konstrueras från datortomografiscanningen och 2D ultraljudsbilderna. För att testa vår hypotes har endast datortomografibilder från sex patienter använts med hypotetiska ultraljudstvärsnitt (HUCS) tagna från CT-A uppföljningarna. AAA-ytan vid baslinjen expanderades i en strukturmekanisk modell genom inre övertryck tills den nådde de hypotetiska ultraljudstvärsnitten. Därefter jämfördes de morfade geometrierna med de CT-A-baserade geometrierna. Geometriavvikelsen mellan de beräknades genom avståndsmätningar. Även, rupturriskindikatorerna volymer och spänningar jämfördes. Slutligen, genom en känslighetsanalys undersöktes effekten av positioneringen av hypotetiska ultraljudstvärsnitten på volymerna och spänningarna. Resultaten visar att en adekvat geometri kan konstrueras genom den undersökta koncepten av morfning. De genomsnittliga avstånden mellan de morfade och CT-A-baserade geometrierna är 2-4 mm. Genomsnittliga volymskillnaderna för de sex patienterna är mellan 3.8-16.2 %. Väggspänningarna för de morfade och CT-A-baserade geometrierna är nära enbart för den första uppföljningen.

Cleavage fracture is one of the most severe failure modes in low alloy ferritic steel structures and the fracture toughness is strongly dependent on the size of the specimen, crack depth and temperature. This thesis investigates how the fracture toughness is affected under conditions that relates to size and constraint effects through a fracture mechanical experiment test series. Furthermore, modeling the experiment with a non-local weakest link model to investigate the importance of the stress measure and how the model parameters can be determined for yielding the best result. The experiment is divided into two sets of testing, a pre-test series to determine an appropriate testing temperature for the main test series. The second set consists of four groups with different sizes and crack depth with 12 specimens in each group. The testing temperature was determined to be -155 ◦C. For the large sized test specimen with a shallow crack, the master curve fails to accurately predict the probability of failure by overestimating the fracture toughness. This is not the case for the small test specimens which indicates that the size effects exceeds the low constraint effects for larger sized test specimens and development of the master curve method is needed. When evaluating the stress state in front of the crack tip in the non-local weakest link model, the results yields the least residual error was obtained when using a large sized specimen with high constraint together with a small sized specimen with low constraint for prediction of the probability of failure.

The objective of this thesis has been to investigate the effect a liquid shim has on the bearing strength of a composite bolted joint. The shim is necessary to close gaps that occur during the assembly of the joints, preventing the structural parts from being fastened correctly. The shim however increases the load eccentricity of the joint and will have a negative effect on the joint strength, but the significance of this weakening is not well understood.This thesis primarily focuses on a parametric finite element study on the effect the liquid shim has on the bearing of both a homogenised carbon fibre/epoxy model and a fully detailed laminate model based upon the same material. Parameters studied were the plate and shim thicknesses, lateral support, number of fasteners, bolt pre-tension and bolt diameter and the relative strength decreases were documented.A literature study was also conducted to consider previous results concering the strength change due to the inclusion of a shim. It was found that the results show a large spread dependent on material system, geometry and assumptions regarding numerical behaviour. The finite element simulation was compared with the results from these studies, showing fairly good agreement.The analysis conducted has shown that there is a major increase in stress and strain on the bearing surface because of the shim. Moreover, it is shown that this strength reduction is dependent on both model and parameters studied, which necessitates experimental testing in order to verify which is the more applicable for future methodology.

Bending stiness is one of the most important mechanical properties in paperboard making,giving rigidity to panels and boxes. This property is currently only possible to measure bydestructive measure o the production line. The current quality control method is decient byassuming a non-realistic consistency of the paperboard properties along the machine direction.The objective of this thesis is to predict the thickness and bending stiness of the nal boardsfrom process data.Two modelling approaches are used: the rst model calculates the bending stiness from acalculated thickness, while the other one uses the measured baseboard thickness. Both modelsuse common inputs such as material properties and grammage measurement. The grammage istaken from the online baseboard measurement. The material properties come from laboratorymeasurements and assumptions. It is assumed that the density ratio between the outer andmiddle plies is constant for all product lines, at all times. The TSI of each ply is dened fromtensile testing experiments and nominal bending stiness. It is also assumed that the coatingdoes not contribute to bending stiness. The two models use equations based on laminatetheory assuming orthotropic layers and neglecting the interlaminar shear forces. The modelsuse data of two dierent natures: i.e. laboratory data and online data. Laboratory data is usedas a comparative to evaluate the models' performance of calculated values from online data.The results show various levels of prediction accuracy for dierent paperboard grades. Theaverage thickness predictions are all underestimations within a 5% error while the bendingstiness estimations vary much more from product to product; varying from 9% underestimationto 32% overestimation. The bending stiness prediction for CD is consistently higher thanfor MD for both models. Most product lines have better results with the calculated thickness,approach 1. The calculated thickness is always underestimated and bending stiness is overestimated,hence the better results with the rst approach.The most important conclusion from the models' results is the spread of laboratory measurements,when compared to the predicted values. The large variation most likely comes fromproduction, implying inconsistencies in the manufacturing process that are not accounted forby the models. These modelling approaches have failed to capture the production variationsbecause of the lack of input parameters.

It is only a matter of time before components working in high temperature environments fail due to creep. Design for creep is therefore of vital importance to maximize the lifetime of components and reduce costs that may arise from maintenance and replacement of components. This thesis aims to use metallographical methods and finite element modeling to assess creep damage in a hydrogen reformer. The decommissioned reformer, made of Fe-Ni-Cr alloys, was investigated thoroughly via replica testing, hardness measurements as well as finite element modeling of the welds. An extended literature review was performed to gain a better understanding of creep in Fe-Ni-Cr alloys, welds and the modeling of creep generally. The microstructures of samples from the reformer were analyzed and mapped out in terms of creep damage which were then compared to a creep analysis of the welds with a simulation time of 100 000 h. The FE results yielded high stresses and creep strains with a maximum of 0.95% in the boundaries of the welds which gave realistic representations of strain distributions when compared to the metallographical results. Hardness measurement indicated that a relatively narrow zone with altered mechanical properties is present along the weld boundaries. This area, called the heat affected zone, was found to be most affected by creep with microcracks reaching maximum lengths of 2 mm. The creep strains obtained from simulation did not fall in line with the observed creep damage, it was thus concluded that a material model that considers tertiary creep would yield a more realistic representation in FEM for Fe-Ni-Cr alloys. / Det är bara en tidsfråga innan komponenter som arbetar i högtemperaturförhållanden misslyckas pga kryp. Att designa med avseende på kryp är därmed viktigt för att maximera livslängden och reducera kostnader som kan komma från underhåll och från utbyte av komponenter. I detta examensarbete används metallografiska metoder och finita element modellering för att bedöma krypskador i en vätgasreformer. Vätgasreformern, som är tillverkad i Fe-Ni-Cr legeringar, togs ur drift och undersöktes metallografiskt med hjälp av replikprovning och hårdhetsprovning samt med finita element modellering av svetsar. En djupgående litteraturstudie utfördes för att öka förståelsen av kryp, specifikt i Fe-Ni-Cr legeringar och även modellering av kryp generellt. Mikrostrukturen från utvalda provbitar undersöktes och krypskador kartläggdes för att sedan jämföra med en krypanalys av svetsarna där 100 000 timmars kryp simulerades. Krypanalysen resulterade i höga spänningar och kryptöjningar upp till maximalt 0.95% i svetsgränserna vilket gav realistiska representationer av töjningsdistributionen jämfört med metallografiska resultaten. Hårdhetsmätningar indikerade att ett smalt område med förändrade mekaniska egenskaper fanns utmed svetsgränserna. Detta område, den värmepåverkade zonen, var mest utsatt för krypskador med mikrosprickor uppemåt 2 mm i längd. Kryptöjningar som erhölls från simuleringen gav inte en tillräckligt bra uppskattning av kryptöjningarna – de krypskador som observerades motsvarar lokalt högre töjning. Slutsatsen är att en materialmodell som tar hänsyn till tertiärkryp skulle i det här fallet ge en mer realistisk representation i FEM för Fe-Ni-Cr legeringar.

The optimization of case hardening depth for small gears was investigated with the use of Abaqus and the subroutine DANTE to simulate the formation of the microstructural phases, resulting in residual stresses and increased hardness. This was done with a step wise increment of the carburizing time, resulting in a theoretical maximum for compressive residual stresses at the surface. The heat treatment parameters were then used for case hardening two gears with different carburizing times. The heat treated gears were then tested for tooth root bending fatigue. The fatigue testing resulted in a fatigue limit increase, where the gear with largest simulated compressive stress showed the highest fatigue limit.   Both the heat treated gears were hardness tested and compared with the conducted simulations resulting in an underestimated hardness. An investigation to see whenever the simulations could predict the fatigue outcome beforehand with a probabilistic model was put into place. This resulted in an underestimated fatigue limit in relation to the raw fatigue data. / Optimering av sätthärdningsdjup för små kugghjul undersöktes med Abaqus och subrutinen DANTE, för att simulera uppkomsten av de mikrostrukturella faserna som resulterar i restspänningar. Detta genomfördes med en stegvis ökning av uppkolningstiden som resulterade i ett teoretiskt maximum för tryckspänningar i ytan. Härdningsparametrarna användes sedan för att sätthärda två serier med kugghjul med olika uppkolningstid. Båda kugghjulen testades sedan för kuggrotsböjning med avseende på utmattning. Utmattningsprovningen resulterade i en ökning av utmattningsgränsen, där kugghjulet med de största simulerade tryckspänningarna resulterade i den högsta utmattningsgränsen.   De härdade kugghjulen hårdhetstestades och jämfördes med genomförda simuleringar, vilket resulterade i en underskattad hårdhet. En undersökning för att se om det är möjligt att prediktera resultatet för en serie utmattningstester via en sannolikhetsmodell användes. Detta resulterade i ett lägre resultat gentemot de genomförda utmattningstesterna.

In a gas turbine rotor, the Blade-Disc attachment is often a critical part. This part needs to endure both high contact stress and high temperature. Thus, the prediction of the life of the attachment becomes important.  Furthermore, the refinement of the Blade-Disc attachment is worth to study, to extend the lifetime of the turbine rotor. In this work, the Blade-Disc attachment is belonging to the gas turbine section.    Geometry modifications based on a 2D FE-model of a blade-disc attachment are performed. Besides of flat contact surface, an alternative curved contact form which creates a barrel on the contact surface is studied. The effect of the different geometries, is studied with respect to high local stresses. The results are evaluated using different methods; deterministic LCF life using EVAL, probabilistic LCF life using ProbLCF and fretting damage parameter evaluation  using the Ruiz-Chen Model.    During this work, geometry modifications based on a 2D Blade-Disc attachment is performed first to study the effect of the different modification results. Then a fretting damage parameter evaluation is carried out, to discuss the crack initiation position of the models with respect to different modification cases. Finally, low cycle fatigue tests are performed to analyse the life cycle of the models.    The result of the work shows at manufactory tolerances can cause a maximum stress increase by at least 60% in the model, especially in the contact surfaces. Also, comparison results shows apply a barrel to the contact surface can effectively decrease the maximum stress in the model, and extend the cyclic life of the attachment. The most suitable barrel height for this work is between 0.05[mm] and 0.015 [mm].

To meet the need of lightweight chassis in the near future, a technological step of introducing anisotropic materials like Carbon Fibre Reinforced Plastics (CFRP) in structural parts of cars is a possible way ahead. Though there are commercially available tools to find suitability of Fibre Reinforced Plastics (FRPs) and their orientations, they depend on numerical optimization and complexity increases with the size of the model. Nevertheless, the user has a very limited control of intermediate steps. To understand the type of material system that can be used in different regions for a lightweight chassis, especially during the initial concept phase, a more simplified, yet reliable tool is desirable. The thesis aims to provide a framework for determining fibre orientations according to the most-ideal loading path to achieve maximum advantage from FRP-materials. This has been achieved by developing algorithms to find best-fit material orientations analytically, which uses principal stresses and their orientations in a finite element originating from multiple load cases. This thesis takes inspiration from the Durst criteria (2008) which upon implementation provides information on how individual elements must be modelled in a component subjected to multiple load cases. This analysis pre-evaluates the potential of FRP-suitable parts. Few modifications have been made to the existing formulations by the authors which have been explained in relevant sections. The study has been extended to develop additional MATLAB subroutines which finds the type of laminate design (uni-directional, bi-axial or quasi-isotropic) that is suitable for individual elements.  Several test cases have been run to check the validity of the developed algorithm. Finally, the algorithm has been implemented on a Body-In-White subjected to two load cases. The thesis gives an idea of how to divide the structure into sub-components along with the local fibre directions based on the fibre orientations and an appropriate laminate design based on classical laminate theory.

With today’s increase in rail traffic the impact of noise on the people near railway lines is increasing. To control this problem European Union regulations, including TSI (Technical Specifications for Interoperability) Noise, has come into force by implementing many strict norms on new railway vehicles put on the market. One TSI regulation is limiting the acceleration noise, which in turn calls for low noise solutions for drive systems which typically governs the vehicle noise at low speeds, up to around 80 Km/hr. This regulation on railway noise has become a major challenge for many train manufacturers. This calls for electromagnetic-Vibration-Acoustics multi physics analysis of the motor. The thesis mainly focuses on numerical modelling of the electromagnetic-vibro-acoustics system. Ideally such models can compute the audible magnetic sound power radiated from the motor as a function of its speed, PWM strategy applied and geometry. Here a pulse modulated permanent magnet traction motor was modelled with finite elements (FE), using a commercial software. Thereafter, the dynamic characteristics of the motor was analysed by FE modal analysis (eigen-frequencies and eigen-modes) as well as by point force frequency response analysis. The FE model was validated by comparing the Eigen-modes, Eigen-frequencies and point accelerance with the experimental modal analysis results. Thereafter, frequency response analysis was performed to calculate the vibration velocities on the surface of the stator frame using realistic electromagnetic forces. These forces were calculated with a dedicated motor analysis tool (FLUX). Moreover, the vibration velocities calculated were used in boundary element model to calculate the radiated sound power and the directivity. Finally the calculated vibration and sound power levels were compared with measurement results.

The acoustics in train compartments is an important part of the comfort when travelling. To improve the acoustics, active noise control (ANC) can be used to create local quiet zones at the passenger ear position. In this thesis the fundamental ANC theory is explained and the possibilities and limitations with the technique are identified. An ANC system which uses the virtual microphone technique is implemented and quiet zones are realized at a chair in a train compartment studio. The performance of the ANC system is evaluated with a Styrofoam head model with built in microphones that is used to produce contour plots of the quiet zone shape and attenuation level. The results show that the 10 dB quiet zone is relatively large covering more than a square decimeter in low frequencies and decreases with frequency. Head movements effects are also evaluated and the results show that the system is very sensitive to head movements, especially in higher frequencies. In order to find an optimal positioning of the system components, several experiments have been made. From these it is concluded that varying noise incidence is problematic to some extent. Ways of handling the problems are presented and if the problems were properly dealt with ANC could be an effective way of reducing noise in passenger train compartments.