The thesis deals with design magnetorheological strut of vibration isolation adapter for cosmonautics. For its optimization is necessary to create several virtual models. The dynamic model of the mechanism - the Stewart platform, rheological model for determining the damping force of MR damper and model of the magnetic circuit to guarantee the required intensity in the gap. These models, along with controls models that are primarily concerned with strength calculations, will help with design. Designing using virtual models requires constant monitoring and verification. It is a rather broad topic including eliminate vibration also kinematics, dynamics, hydraulics, pneumatics and last but not least electronics and magnetism. It is necessary to communicate with experts in their field and use their knowledge and experience to create, but also to control of the individual models. The thesis was created in cooperation with Honeywell Aerospace Division (ESA).

The aim of this thesis is to undertake simplified design and assessment of cofferdam under vertical surcharge in the form of virtual project. Cofferdam constructed on the sea shore must be able to withstand all loads to enable construction of cut and cover tunnel. As a part of the design it is required to assess ground conditions and it is necessary to review feasibility of the structure on the sea. The construction will be described in construction phases and graphically demonstrated in construction sequence drawing. Because the structure is designed for life time of five years, temperature load on struts is studied in the thesis and further considered in structural analysis. Furthermore, it is required to compare analytical models from GEO5 and PLAXIS. Horizontal frame is analysed separately in Scia Engineer. Structural members – cofferdam wall, waler beam and strut are checked in this thesis. For the design of the cofferdam wall second order theory is considered. All mentioned requirements were accomplished with help of corresponding Eurocodes, books and technical advice. Results of this work are feasible and it was possible to design all members to enable construction of the cut and cover tunnel. The phasing was designed such that deformation of the cofferdam is minimalized and use of machinery is limited to machines on temporary platforms. Comparison of two different analytical models showed that different soil modelling has great effect on internal forces, even though the shape of the bending curve is very similar, values obtained from PLAXIS software are much higher. Assessment of the structural members is done according to Eurocode 3, and horizontal frame is checked also against disproportionate collapse.

<p>U disertaciji su analizirani armiranobetonski ravanski nosači<br />primenom metode pritisnutih štapova i zatega. Optimizacija nosača<br />urađena je diskretnom topološkom otimizacijom kojom se pun nosač<br />zamenjuje ekvivalentnim rešetkastim. Dat je predlog algoritamskog<br />dobijanja Strut-and-Tie modela koji je implementiran u program sopstvene<br />izrade pod nazivom &bdquo;ST method&ldquo;. Provera pouzdanosti predloženog<br />algoritma utvrđena je primerima iz referentne literature, sopstvenim<br />eksperimentalnim ispitivanjem i numeričkom analizom u komercijalnim<br />programima. Rezulatati analiza su pokazali da se predloženi algoritam u<br />programu &bdquo;ST method&ldquo; može koristiti za dobijanje Strut-and-Tie modela i<br />njihovo dimenzionisanje i da se pri odabiru nekih modela mora koristiti<br />inženjersko iskustvo.</p> / <p>In dissertation thesis, reinforced concrete plane members have been analyzed by<br />the Strut-and-Tie method. Optimizing of the members is made by discrete<br />topological otimization which replaces full member with equivalent truss system.<br />Algorithmic manner of Strut-and-Tie model obtaining has been suggested, which<br />is implemented in the program of an own creation called &quot;ST method&quot;. The<br />reliability of the proposed algorithm is determined by the examples from reference<br />literature, an own experimental test and numerical analysis in commercial<br />programs. The results of the analysis showed that the proposed algorithm in the<br />&quot;ST method&quot; can be used to obtain Strut-and-tie models and their dimensioning<br />and that in certain models, the engineering experience must be used.</p>

In the automobile industry, there is a big push for the automotive car manufacturers to base engineering decisions on the results of Computer Aided Engineering (CAE) solutions, and to transform the prototyping and testing, from a costly iterative process to a final verification and validation step. The variability in components material properties and environmental conditions together with the lack of knowledge about the underlying physics of complex systems often make it impractical to make reliable predictions based on only deterministic CAE models. One such area is the CAE modelling of cast aluminium components. These cast aluminium components have gained a huge relevance in the automobile industries due to their commendable mechanical properties. The advantage of the cast aluminium alloys are being a well-established alloy system in manufacturing processes, their functional integrity and relatively low weight. However, the presence of pores and micro-voids obtained during the manufacturing process constitutes a specific material behaviour and establishes a challenge in modelling of the cast materials. Furthermore, the low ductility of the materialdemands for the advanced numerical model to predict the failure. The main focus of this master thesis work is to investigate modelling technique of a cast aluminium alloy component, a spring tower, for a drop tower test and validate the predicted behaviour with the physical test results. Volvo Car Corporation currently uses a material model provided by MATFEM for cast aluminium parts which are explored in this thesis work, to validate the material model for component level testing. The methodology used to achieve this objective was to develop a boundary condition to perform component level tests in the drop tower and to correlate these with the obtained results found by using various modelling techniques in the explicit solver LS-DYNA. Therefore, precise and realistic modelling of the drop tower is crucial because the simulation results can be influenced by major design changes. A detailed finite element model for the spring tower has been developed from the observations made during the physical testing. The refined model showed good agreement with the existing model for the spring tower and observations from physical tests.

In this paper, we present a new compact hydraulic linear actuator. The concept is developed to change the rolling piston diameter of an active air spring during usage. By doing so, the air spring can actively apply pressure and tension forces. The actuator is designed for small movements at high forces. It is insensitive to side forces, which are introduced by the bellows rolling on the rolling piston of the air spring. A diaphragm sealing is used to minimize friction. Hence a precise adjustment of small displacements at high dynamics is possible and the system is completely leakage-free. We describe the design and development of this actuator and show first measurement results from preliminary tests to show its functionality.

Detta examensarbete vid Luleå tekniska universitet har utförts i samarbete med avdelningen för byggkonstruktionvid det nordiska konsultföretaget Norconsult AB. Arbetet bygger på en önskan från Norconsultatt ta fram en beräkningsmodell för höga balkar i överensstämmelse med Eurokod 2 motsvarande densom finns i BBK 04. Eurokod 2 har endast en knapphändig beskrivning av hur höga balkar bör dimensioneras.Detta skapar frustration och osäkerhet hos konstruktörer. Den tidigare svenska betongnormen,BBK 04, innehöll en tydlig och enkel mer empirisk beräkningsmetod för höga balkar, vilket gav en störresäkerhet vid projekteringen. Arbetet begränsas till att studera enkelt upplagda och kontinuerliga balkar i två spann belastade med enpunktlast mitt i vartdera spannet. Geometrin är densamma för samtliga balkar och armeringsmängdenvarieras tillsammans med brottlasten. Initialt utfördes en litteraturstudie för att erhålla en fördjupad kunskap om området samt att bygga uppen förståelse för teorin för höga balkar och den fackverksmodell som används i Eurokod 2. Vidare presenterasen försöksrapport, Rogowsky et al. (1983), som redovisar en experimentell laboratoriestudie därhöga balkar belastas till brott. Resultaten som presenteras är brottlast, töjning i betong och armering,sprickmönster samt nedböjning. Fyra enkelt upplagda och fyra kontinuerliga balkar väljs ut för vidarejämförelse och analys. Härvid används det ickelinjära beräkningsprogrammet ATENA 2D, där studeradebalkar modelleras. Handberäkningar enligt EK2 och BBK 04 utförs för respektive balk och tillhörandearmeringsmängd beräknas. En maximal brottlast itereras fram för respektive balk och beräkningsmetod (EK2 eller BBK 04). Armeringsmängdensom ges av denna beräkning modelleras i ATENA 2D och motsvarande balk analyseras.Resultaten jämförs sedan. Erhållna resultat sammanställs och jämförs med varandra: Rogowsky et al. (1983), ATENA 2D och handberäkningarnaenligt både Eurokod 2 och BBK 04. Jämförelsen visar att det finns få likheter mellan EK2och BKK 04, med avseende på erhållen armeringsmängd. BBK kräver generellt större armeringsmängdän Eurokod 2. Studien visar att beräkningarna med ATENA 2D stämmer väl överens med laboratorieförsöken.Resultaten visar även att antaganden enligt Eurokod 2 stämmer väl överens med hur de studeradebalkarna beter sig i verkligheten. En enkel beräkningsmodell som motsvarar BBKs konservativa modell är inte möjlig att ta fram inom deramar och begränsningar som finns för detta examensarbete. Istället sammanställs en modell i form av enpunktlista som förtydligar, sammanfattar och exemplifierar den mer verklighetstrogna beräkningsgångenför höga balkar enligt Eurokod 2.

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No description available.

Multidisciplinary design optimization (MDO) requires many designs to be evaluated while searching for an optimum. As a result, the calculations done to evaluate the designs must be quick and simple to have a reasonable turn-around time. This makes aerodynamic calculations in the transonic regime difficult. Running computational fluid dynamics (CFD) calculations within the MDO code would be too computationally expensive. Instead, CFD is used outside the MDO to find two-dimensional aerodynamic properties of a chosen airfoil shape, BACJ, at a number of points over a range of thickness-to-chord ratios, free-stream Mach numbers, and lift coefficients. These points are used to generate surrogate models which can be used for the two-dimensional aerodynamic calculations required by the MDO computational design environment. Strip theory is used to relate these two-dimensional results to the three-dimensional wing. Models are developed for the center of pressure location, the lift curve slope, the wave drag, and the maximum allowable lift coefficient before buffet. These models have good agreement with the original CFD results for the airfoil. The models are integrated into the aerodynamic and aeroelastic sections of the MDO code. / Master of Science

Abstract : Deep reinforced concrete beams are commonly used as transfer girders or bridge bents, at which its safety is often crucial for the stability of the whole structure. Such elements are exposed to the aggressive environment in northern climates causing steel-corrosion problems due to the excessive use of de-icing salts. Fiber-reinforced polymers (FRP) emerged as non-corroded reinforcing materials to overcome such problems in RC elements. The present study aims to address the applicability of concrete deep beams totally reinforced with FRP bars. Ten full-scale deep beams with dimensions of 1200 × 300 × 5000 mm were constructed and tested to failure under two-point loading. Test variables were shear-span depth ratio (equal to 1.47, 1.13, and 0.83) and different configurations of web reinforcement (including vertical and/or horizontal web reinforcement). Failure of all specimens was preceded by crushing in the concrete diagonal strut, which is the typical failure of deep beams. The test results indicated that, all web reinforcement configurations employed in the tested specimens yielded insignificant effects on the ultimate strength. However, strength of specimens containing horizontal-only web reinforcement were unexpectedly lower than that of specimens without web reinforcement. The web reinforcement’s main contribution was significant crack-width control. The tested specimens exhibited reasonable deflection levels compared to the available steel-reinforced deep beams in the literature. The development of arch action was confirmed through the nearly uniform strain distribution along the length of the longitudinal reinforcement in all specimens. Additionally, the basic assumption of the strut-and-tie model (STM) was adequately used to predict the strain distribution along the longitudinal reinforcement, confirming the applicability of the STM for FRP-reinforced deep beams. Hence, a STM based model was proposed to predict the strength of FRP-reinforced deep beams using the experimental data, in addition to the available experimentally tested FRP-reinforced deep beams in the literature. Assessment of the available STMs in code provisions was conducted identifying the important parameters affecting the strut efficiency factor. The tendency of each parameter (concrete compressive strength, shear span-depth ratio, and strain in longitudinal reinforcement) was individually evaluated against the efficiency factor. Strain energy based calculations were performed to identify the appropriate truss model for detailing FRP-reinforced deep beams, hence, only four specimens with vertical web reinforcement exhibited the formation of two-panel truss model. The proposed model was capable to predict the ultimate capacity of the tested deep beams. The model was also verified against a compilation of a data-base of 172 steel-reinforced deep beams resulting in acceptable level of adequacy. The ultimate capacity and performance of the tested deep beams were also adequately predicted employing a 2D finite element program (VecTor2), which provide a powerful tool to predict the behavior of FRP-reinforced deep beams. The nonlinear finite element analysis was used to confirm some hypotheses associated with the experimental investigations. / Résumé : Les poutres profondes en béton armé (BA) sont couramment utilisées comme poutre de transfert ou coude de pont, comme quoi sa sécurité est souvent cruciale pour la sécurité de l’ensemble de la structure. Ces éléments sont exposés à un environnement agressif dans les climats nordiques causant des problèmes de corrosion de l’acier en raison de l’utilisation excessive de sels de déglaçage. Les polymères renforcés de fibres (PRF) sont apparus comme des matériaux de renforcement non corrodant pour surmonter ces problèmes dans les BA. La présente étude vise à examiner la question de l'applicabilité des poutres profondes en béton complètement renforcées de barres en PRF. Dix poutres profondes à grande échelle avec des dimensions de 1200 × 300 × 5000 mm ont été construites et testées jusqu’à la rupture sous chargement en deux points. Les variables testées comprenaient différents ratios de cisaillement porté/profondeur (égal à 1.47, 1.13 et 0.83) ainsi que différentes configurations d’armature dans l’âme (incluant un renforcement vertical avec ou sans renforcement horizontal). La rupture de tous les spécimens a été précédée par l’écrasement du béton dans le mât diagonal, ce qui est la rupture typique pour les poutres profondes en BA. Les résultats ont révélé que toutes les configurations de renforcement de l’âme employées dans les spécimens d'essais avaient un effet négligeable sur la résistance ultime. Toutefois, la résistance des spécimens contenant uniquement un renforcement horizontal était étonnamment inférieure à celle des spécimens sans renforcement. La contribution principale du renforcement de l’âme était dans le contrôle de la largeur de fissuration. Les spécimens examinés présentaient une déflexion raisonnable par rapport à ce qui est disponible pour les poutres profondes renforcées en acier dans la littérature. Le développement de l'effet d'arche a été confirmé par la distribution quasi uniforme des déformations le long du renforcement longitudinal dans tous les spécimens. En outre, l'hypothèse de base du modèle des bielles et tirants (MBT) a été utilisée adéquatement pour prédire la distribution de déformation le long du renforcement longitudinal, confirmant l'applicabilité du MBT pour les poutres profondes armées de PRF. Par conséquent, un modèle basé sur un MBT a été proposé afin de prédire la résistance des poutres profondes renforcées de PRF en utilisant les données expérimentales en plus de la mise à l'épreuve expérimentalement des poutres profondes renforcées de PRF trouvées dans la littérature. Une évaluation des MTB disponibles dans les dispositions des codes a été menée afin de déterminer les paramètres importants affectant le facteur d'efficacité de la bielle. La tendance de chaque paramètre (la résistance à la compression du béton, le ratio de cisaillement porté/profondeur, et la déformation dans le renforcement longitudinal) a été évaluée individuellement contre le facteur d'efficacité. Des calculs basés sur l’énergie des déformations ont été effectués pour identifier le modèle de treillis approprié afin de détailler les poutres profondes renforcées de PRF. Par conséquent, seulement quatre spécimens avec un renforcement vertical dans l’âme présentaient la formation de modèles avec deux panneaux de treillis. Le modèle proposé a été capable de prédire la capacité ultime des poutres profondes testées. Le modèle a également été vérifié contre une base de données de 172 poutres profondes renforcées en acier aboutissant en un niveau acceptable de pertinence. La capacité ultime et la performance des poutres profondes testées ont été également adéquatement prédites employant un programme d'éléments finis en 2D (VecTor2), ce qui fournira un puissant outil pour prédire le comportement des poutres profondes renforcées de PRF. L'analyse non linéaire par éléments finis a été utilisée afin de confirmer certaines hypothèses associées à l'étude expérimentale.