Ankylosing Spondylitis (AS), or Bechterew’s disease, is an inflammatory rheumaticdisease that through the formation of additional bone tissue in the spine eventuallyleads to the complete fusion of the vertebrae, in effect turning the spine into one longbone. Due to the reduced flexibility of the spine with the long lever arms, spinalfractures in AS-patients are relatively common even after minor trauma. The aim of this thesis was to use an existing finite element model of a healthy spineand adapt it to the conditions of AS, thus gaining some insight into the effects ofsurgical stabilization of cervical fractures, using posterior screws and rods. Althoughthis type of surgery is often performed, it has not been previously investigated in abiomechanical model. This thesis should be considered as a starting point for how afinite element model of the spine could be used to investigate the effect of spinalimplants in the case of a fracture in the ankylosed spine. An existing FE-model was modified to some of the conditions of AS: The vertebraewere fused by adding ossifications at the intervertebral discs (with the Head-C1 andC1-C2 joints left mobile). A fracture was simulated at the C6C7 disc level. Fourdifferent implant configurations were tested: Short instrumentation C6C7, mediuminstrumentation C5toT1, long instrumentation C3toT3, and a long instrumentationC3C6C7T3 with skipped intermediate levels. Three loads (1.5g, 3.0g, 4.5g) wereapplied according to a specific load curve. Kinematic data such as the gap distance inthe fracture site were obtained. Furthermore the stresses in the ossified parts of thediscs were evaluated. It was shown that the chosen methods of adapting the model to the AS conditions, andmodeling the fracture and implant, changed the kinematics so that less movementoccurred between the vertebra, which is typical for AS. Measured as fracture gap, alltested implant configurations were equally good at stabilizing the fracture, althoughthey all allowed more movement than the non-fractured AS-model did. All implantconfigurations were also able to stabilize the fracture in terms of the horizontal translation in the fracture. The disc ossifications were somewhat shielded from stress for those ossifications that were within the range of the implant. This was so for all implant configurations. No increased stress was observed in the ossifications immediately outside the range for the implants, relative the non-fractured AS-model. For the C6C7 and C5toT1 implant configurations as well as the non-fractured ASmodel,the stresses were highest at the T1T2 level. Stresses in the ossifications in the thoracic spine were generally low, apart from the T1T2 level. The results show that the chosen AS-adaptations and the modeled implant seem reasonable for testing some of the considerations of cervical fractures in the ankylosed spine as well as for some implant configurations. The results also make it possible to speculate about the optimal type of implant. The effects of screw placement and anchoring, osteoporosis, muscle activation and possible spinal deformity on the implant stability were not investigated, and should be a matter for further studies. / Ankyloserande Spondylit (AS), eller Bechterew’s sjukdom, är en inflammatorisk, reumatisk sjukdom som innebär att ny benvävnad formas i ryggraden. Detta leder till att kotorna slutligen smälter samma. I praktiken leder detta till att ryggraden fogas samman till ett enda långt ben. Vid en reducerad flexibilitet med långa hävstänger är frakturer i kotpelaren relativt vanliga för patienter med AS även vid mindre trauma. Syftet med denna uppsats var att använda en existerande FE-modell av en frisk rygg och nacke, och anpassa den till det tillstånd som är typiskt för AS. Vidare var syftet att erhålla insikt om hur kirurgisk stabilisering med skruvar och stänger av en fraktur i nacken beter sig. Trots att denna typ av operation utförs förhållandevis ofta, så har detta inte tidigare undersökts i någon biomekanisk modell. Denna uppsats kan ses som en utgångspunkt för hur en FE-modell av ryggraden kan användas för att undersöka effekten av stabiliserande implantat av en fraktur vid AS. En existerande FE-modell modifierades för att överensstämma med några av de villkor som gäller vid AS: Kotorna fogades samman via förbeningar i diskarna. (Huvud-C1 och C1-C2-lederna lämnades rörliga). En fraktur simulerades i C6C7- nivån. Fyra olika konfigurationer av implantat provades: Kort implantat C6C7, mellanlångt implantat: C5tillT1, långt implantat C3tillT3 och ett långt implantat C3C6C7T3 där mellanliggande kotor hoppades över. Tre lastfall (1.5g, 3.0g, 4.5g) applicerades enligt en specifik lastkurva. Kinematisk data såsom “fracture gap distance” i frakturen registrerades. Vidare registrerades också spänningarna i de förbenade delarna av diskarna. Det var möjligt att, genom att anpassa modellen till AS och modellera fraktur och implantat, påverka nackens kinematik så att mindre rörelse skedde mellan kotorna, vilket är typiskt för AS. Med utgångspunkt i mätningarna av “fracture gap distance”, var det möjligt för alla konfigurationer av implantat att stabilisera frakturen, även om implantaten tillät mer rörelse än AS-modellen som saknade fraktur. Detta gällde även för horisontell translation i frakturen. Vad gällde spänningarna i förbeningarna så avlastades dessa för de förbeningar som var belägna inom implantatets räckvidd. Detta gällde för alla implantatkonfigurationer. Inga spänningskoncentrationer observerades i förbeningarna precis utanför implantatens räckvidd i förhållande till AS-modellen utan fraktur. Vad gällde C6C7 och C5toT1 implantaten, liksom ASmodellen utan fraktur, så registrerades de högsta spänningarna i T1T2-nivån. Spänningarna i förbeningarna i bröstryggen var generellt låga, bortsett från T1T2- nivån. Resultaten visade att de valda anpassningarna till AS och sättet att modellera implantaten verkade vettiga för att undersöka några av de överväganden som uppstår vid nackfrakturer i en ankyloserad kotpelare, samt ett par implantatvarianter.  Resultaten möjliggör även spekulationer kring vilken typ av implantat som är optimal. Huruvida implantatstabiliteten påverkades av placeringen av skruvar, infästningen i benvävnaden, osteoporos, muskelaktivering och möjlig missbildning av ryggen undersöktes inte. Detta kan undersökas i framtida studier.

This thesis describes a comparative study between two calculations methods for life estimates of a welding joint. The two studied methods are the Effective Notch and Linear Elastic Fracture Mechanics (LEFM). The effective notch method is today used at GKN and gives an equitable accuracy relative the work effort for the method. The use of LEFM is more accurate, but on the expense of calculation time and complexity. The aim with this thesis was to investigate if the LEFM method is feasible for the day-to-day work at GKN Driveline. In the effective notch method, inaccuracies and the stress concentration in the weld are collected in a fictional notch with a radius of 0.05 mm. The stress amplitude is evaluated in the notch and the relation between stress and fatigue cycles is collected in an S-N curve for the weld. In the LEFM method a small crack is introduced in the weld and a few number of fatigue cycles are performed to simulate crack growth. The real numbers of fatigue cycle necessary to fracture the weld are calculated by integrating Paris Law. The accuracy of the methods was measured with correlation between simulations and results from experiments. The accuracy for the effective notch was widely spread between different designs, indicating sensitivity to the notch configuration and location. The LEFM method gave better accuracy but at the cost of increased computational time. The LEFM method was not feasible to conduct on two of three investigated weld designs and to implement LEFM in GKN’s daily work requires that the method is developed to work on all design solution the company offers.

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De två fysiologiska egenskaper som har störst betydelse för en individs uthållighet är maximalsyreupptagningsförmåga och den så kallade övre laktattröskeln. Dessa egenskaper tas bäst fram genomett så kallat tröskeltest och ett maxtest, vilket en litteraturstudie och en intervju av en expert i ämnethar visat. Egenskaperna skulle sedan kopplas till en Matlabmodell utvecklad för att simulera bland annatutmattning för en individ på en given bana. För att åstadkomma detta genomfördes ett tröskeltest ochett maxtest på två individer för att mäta den övre laktattröskeln och den maximalasyreupptagningsförmågan. Testerna utfördes på Aktivitus i Solna. Därefter simulerades maxtesternaför varje individ i denna Matlabmodell. Det visade sig att den övre laktatröskeln hade en ganska direkt koppling till Matlabmodellen vilketinnebär att man kan föra in uppmätta värden direkt i modellen medan den maximalasyreupptagningsförmågan koppling till modellen behöver undersökas närmare. Experimenten har genomförts som en del av ett projekt som drivs av professor Anders Eriksson påKTH och hans kollegor från Karolinska Institutet och Mittuniversitetet. Teknik/arbetsekonomi somhar betydelse för uthålligheten har i detta arbete förbisetts. För att få bättre och säkrare resultatbehöver fler tester utföras. / The two most important physiological properties to determine an individuals endurance are maximumoxygen uptake and the anaerobic threshold. These properties can be obtained with a threshold test anda max test, which literature and an interview with an expert in the field showed. The properties would then be linked to a Matlab model developed to simulate exhaustion for anindividual on a given track. To achieve this, a threshold test and a max test were performed on twoindividuals to measure the maximum oxygen uptake and the anaerobic threshold. The tests wereperformed in Solna by Aktivitus. Afterwards the max tests were simulated in the Matlab model for thetwo individuals. It turned out that the anaerobic threshold is directly linked to the Matlab model which means that youcan put measured values directly into the model while the maximum oxygen uptake need furtherinvestigation. The experiments have been performed as part of a project lead by Professor Anders Eriksson fromKTH and his colleagues from Karolinska Institutet and Mittuniversitetet. Technique which is animportant factor in endurance has been overlooked. To obtain better and more accurate results moretests should be performed.

Gas turbines overall theoretical performance analysis can be performed by using several thermodynamic theories and equations with the help of design parameters. However, limited availability of the design parameters will complicate the analysis. The turbines manufactures published a limited amount of data, while important parameters remain hidden and this available information is not enough for overall gas turbine cycle analysis. A theoretical model based on Mathcad software is already available in literature to reveal such hidden gas turbine parameters nevertheless requires improvements in various facets.Five main parameters commonly published by the gas turbine manufactures in the catalogue are exhaust temperature of flue gas, exhaust mass flow rate, overall efficiency, electrical output and compression ratio of the compressor. Theoretical model was developed to obtain all the hidden thermodynamic parameters by using available catalogue data with realistic assumptions. The engineering equation solver (EES) program has been used as a platform to rebuild the theoretical model and the graphical user interface of the new programme. After obtaining the hidden thermodynamic parameters, an exergy analysis has been carried out for the gas turbine. The developed EES programme is expected to be used in the learning laboratory at the Department of Energy Technology, The Royal Institute of Technology (KTH), Stockholm, incorporated into CompEdu learning platform.

The ventilation systems are becoming more compact so as to save buildings space. In return, the velocity, in ventilation units, is increased and the air flows are also more turbulent. The hotwire investigation aims to correlate this increase of turbulence with the increase of the noise level. The investigation was done for industrials purposes and is based on empirical researches completed with theoretical knowledge. For the investigation, the hotwire sensor is chosen for its ability to detect small velocity fluctuations at high frequency. Two different prototypes are designed in order to highlight the influence of the turbulence level in the sound generation, especially at ventilation outlets. A procedure is also introduced, in which the hotwire is used for the turbulence measures and a reverberation room for the sound measurement. General conclusions are finally identified and explain the influence of the turbulence in the sound generation mechanisms. The influence of the prototypes geometries, on both the sound and the turbulence, is analyzed and the master thesis describes how the air flow velocity in ducts and the static pressure could modify both the turbulence and the sound levels. The stated conclusions imply that the designers of new ventilation systems should take into account the turbulence generated by their experimental product if they want to conserve good sound properties.

Rotary machinery systems are widely used in different industries. As they have rotational movements, the resonances will be the function of rotational speed. Nowadays, there are different CAE (Computer Aided Engineering ) softwares that use finite element method to solve complex problems by simplifying the model to a limited DOF (Degree Of Freedom) system. Some of the CAE software have built-in module for rotary machinery to solve eigenvalue problems, unbalance response, stability, etc. COMSOL multiphysics 1 is a CAE software that can deal with structural mechanics. There is not any specific module for the rotor dynamics analysis in COMSOL multiphysics version 4.2a; however, It is possible to make a model based on 1D beam elements or even structural mechanics elements and solve the problem by using equivalent gyroscopic moment and unbalance force terms. The scope of this thesis is based on 1D beam element solution. Moreover, the result of the COMSOL solution has been compared with ANSYS based on 3D element 2. In this thesis, the main purpose is implementing rotor dynamics concepts in COMSOL multiphysics based on beam element 3 . Second chapter is focused on the theory part of the rotordynamics where the equations in the stationary cases are derived which measn the rotational speed of the rotor does not change by time; moreover, a brief overview of finite element method has been mentioned. The third chapter covers the implementation of the rotor dynamics in COMSOL where a very brief overview of different COMSOL’s sections that are used in this thesis are described; Moreover, load implementation , 3D mapping based on extrusion integration and comparison a result data with ANSYS are mentioned. In the fourth chapter rotordynamics analysis is described based on Campbell plot 4, stability analysis and harmonic response from a model that is made in COMSOL. Final chapter is the conclusion part about this thesis based on the results that have been shown.

In ABB, Soundplan is the usually used software to predict the industrial noise for power transmission plants. However, the sound sources in Soundplan are modeled as point sources between which there are no sound reflections. For the real situation, the sound sources are very big and can be regarded as noise barriers. So it is important to take the reflections between sound sources into consideration.COMSOL Multiphysics is Finite Element Method (FEM) software which can model acoustic object with sound-reflective boundaries. First, the COMSOL model for single component inside the power transmission plant will be discussed. Then the COMSOL model for the whole plant will be calculated at different frequencies. The total sound pressure level at different receivers will be compared between COMSOL and Soundplan results. COMSOL can be used to predict the sound propagation of the power transmission plant and it can give different results when the outline of the plant is changed.

Direct numerical simulation (DNS) of steady flow, with Re = 750 at inlet, through stenosed pipe has been done to study transition and turbulence of the flow in the post-stenosis area. The pipe has 75% constriction by area reduction and 5% eccentricity of the main pipe diameter at the throat. A sinusoidal Gaussian force is implemented to keep turbulent in the domain. The result shows acceptable agreement with previous study has  been done by Fischer et al. [4]. We simulated the case by NEK5000 which benefits from the spectral element method (SEM) as a higher order accurate method. To have a better understanding of the turbulent flow, we have done the modal decomposition to obtain coherent structures. Among several methods for modal decomposition, we considered Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) for current study. The methods have been implemented in Fortran, accelerated using OpenMP and is potentially settled for computation of large data sets. DMD implementation shows 2.5 speed up. The stuctures correspond to the implementation force are extracted by POD however they have not been recognised by dynamic decomposition.

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