This diploma thesis deals with the measurement of the torsion stabilizer characteristics. The beginning of the thesis explains the function of a torsion stabilizer in a vehicle and introduces various technical options of stabilization. Next part is focused on computational simulation of representative stabilizers. Next parts are devoted to proposition of measuring device for torsion stabilizers in the laboratory and execution of the experiment. In the final part multibody model is created to demonstrate achieved results.

This master's thesis focuses on cranktrain of two-cylinder spark ignition engine. Aim of this thesis is the following sequence. Comparing various construction configurations, choosing the best concept, balancing inertial forces of reciprocating and revolving masses and theirs moments within this concept and finally checking the torsion stress.

The purpose of this thesis is design of five-cylinder in-line diesel engine with rubber dumper, with given main parameters, powerstrain design, balancing inertia forces and its moments, modal analysis, calculation of torsion vibrations and design of rubber dumper.

The purpose of this work is design of a five-cylinder in-line diesel engine with the given initial parameters. The work will be analyzed by balancing the engine, remove the effects of unbalanced masses by the unbalance of the crankshaft and separate balancing unit. It will also be analyzed driveline torsion vibration, followed by reducing the effects of torsion vibration by using rubber torsion vibration dampers. At the conclusion will be modal and stress analysis of the crankshaft using the FEM program.

This master’s thesis is focused on a design of the formula student’s anti-roll bar. The beginning of the thesis is devoted to the introduction of the anti-roll bar function and the explanation of its effect on a vehicle including the analysis of various constructions. Second part deals with the Formula Student competition. There is the analysis of the formula Ford’s anti-roll bar as a starting point for our own design. In the section which deals with the anti-roll bar design several alternatives are designed, the stress analysis of components are made and multi body system models are developed for final solutions. These models serve for further analyses of driving characteristics of the vehicle.

The purpose of this thesis is two-cylinder in-line four stroke petrol engine design based on input parameters. The work consists of different variations of designed crankshaft balancing and balancing unit. Calculation method of torsion vibration and crankshaft fatigue failure solution based on stress analysis are included.

The main aim of this master’s thesis is to design the powertrain of turbocharged threecylinder in-line gasoline engine based on given parameters. The work introduces three variants of balancing of inertia moment of rotating masses and balancer unit of first order moment of inertia of reciprocating parts. The thesis also presents calculation of torsion vibration of the powertrain and structural design of the rubber damper. In conclusion a stress analysis of the crankshaft is submitted with and without torsion vibration damper.

Hauptziel dieser Arbeit ist die Klärung der in der Praxis oft getroffenen Annahme, dass die statischen Torsionseffekte eines Windturbinenrotorblatts keinen Einfluss auf die aerodynamische Leistungsbilanz nehmen. Auf dem Markt findet sich ein breites Angebot an Software, mit der die Aeroelastizität von Windturbinenblättern und deren dynamische Stabilität berechnet und geprüft werden kann. Mit diesen Programmen können üblicherweise Schwingungsformen, die dazugehörigen Frequenzen sowie die Überlagerung der Schwingungen, das Flattern und die Stabilität des Rotorblattes berechnet werden [1, 2, 3 und 4]. Konstruktive Maßnahmen in diesem Zusammenhang sind auf die Schwingungstechnik fokussiert [5]. Die dynamische Stabilität ist jedoch nicht maßgebend für die statische Deformation des Windturbinenblattes, bei deren Auslegung auf die Vermeidung von Kollisionen mit dem Turm geachtet werden muss. In diesem Zusammenhang gewinnt die statische Aeroelastizität der Windturbinenblätter an Wichtigkeit. Die zur Verfügung stehenden Berechnungsprogramme ziehen zwar sowohl die dynamische als auch die statische Aeroelastizität in Betracht. Da jedoch in der Regel die dynamischen Torsionsschwingungen der Windturbinenblätter wesentlich höhere Frequenzwerte aufweisen als die Schlag- und Schwenkschwingungen, wird als plausibel angenommen, dass die Rotorblätter grundsätzlich torsionssteif sind. Daher werden bei den handelsüblichen Berechnungsprogrammen sowohl für die Aerodynamik als auch für die Strukturmechanik Vereinfachungen vorgenommen, in denen die statischen Torsionsberechnungen wegfallen. Als Stand der Technik bei den kommerziell erhältlichen Programmen wird die Aerodynamik des Rotors zunächst an einem Modell untersucht, in welchem der Rotor in viele zweidimensionale Profilpolare (mit angenommenen Interpolationsmöglichkeiten) unterteilt ist, wobei die Profilpolare 2DWindkanalmessungen entnommen werden. Die Strukturmechanik bezieht sich in der Regel auf eindimensionale Balkenelemente, die für Biege- und Zuglasten, aber nicht für Torsionsbetrachtungen um die Rotorlängsachse berechnet werden, da die Torsionseffekte als sehr gering und vernachlässigbar eingeschätzt werden. Beim torsionselastischen Windturbinenblatt ist zu erwarten, dass die Last der lokalen Auftriebskräfte und Nickmomente das Rotorblatt um die eigene Längsachse tordieren lässt [6]. Durch den Torsionswinkel nimmt der Auftrieb und somit die Schubkraft des Rotorblattes zu. Da der Torsionswinkel an der Windturbinenblattspitze am größten ist, wird folglich die größte Schlagdeformation ebenfalls im äußeren Bereich des Rotorblattes auftreten. Mit zunehmender Größe des Rotordurchmessers von der Größenordnung 100 m wird erwartet, 10 dass die Torsionslasten einen zunehmenden, nicht mehr vernachlässigbaren Einfluss auf die Wechselwirkung der Aerodynamik und Strukturmechanik einnehmen und somit die Zunahme der Schlagdeformation begünstigen. Daher ist die Aufgabe dieser Arbeit die Klärung der Annahme, dass die statischen Torsionseffekte eines Windturbinenrotorblatts Einfluss auf die aerodynamische Leistungsbilanz nehmen. In den Kapiteln 4 und 5 dieser Arbeit werden daher die Größenordnung der Drehwinkel und die sich daraus ergebende Schlagdeformation mit einem besonderen Augenmerk auf die Torsionseffekte des Rotorblattes ermittelt. Weiterhin werden in der aeroelastischen Berechnung dieser Arbeit die lokalen Deformationen berücksichtigt, da die flexible Haut des Windturbinenprofils durch die aerodynamischen Lasten eine Verformung erfährt, die einen beachtenswerten Einfluss auf die Aerodynamik des Windturbinenprofils hat. Bei immer größer werdenden Profiltiefen wird die Zunahme der lokalen Deformationen der flexiblen Haut des Windturbinenprofils begünstigt, welche durch die aerodynamischen Lasten und Torsion verursacht wird, die ihrerseits die Aerodynamik beeinflussen. Da der Fokus auf den lokalen Deformationen und Torsionseffekten liegt, wird hier auf sonst wichtige Parameter wie z.B. Windgeschwindigkeitsgradient, und Rotorebenenneigung verzichtet und somit eine stationäre Strömung angenommen. In einem iterativen Verfahren wird zunächst die aerodynamische Lastverteilung des Rotorblatts ermittelt. Die Ergebnisse werden in einem strukturmechanischen Programm auf das Rotorblattmodell übertragen. Die aerodynamischen Lasten und die Zentrifugalkräfte erzeugen einen Gleichgewichtszustand und eine neue Deformation des Rotorblattes. Der neue Gleichgewichtszustand wird für die Ermittlung der Aerodynamik für den nächsten Berechnungsschritt benutzt. Das iterative Verfahren wird so lange fortgesetzt, bis sich eine Konvergenz eingestellt hat. Hierzu sollen die Konvergenzkriterien berücksichtigt und dokumentiert werden, um somit die Berechnungsgenauigkeit des Antriebsmoments der Turbinenwelle beurteilen zu können. Für die Untersuchungen werden sowohl ein Balkenmodell als auch ein Schalenmodell benutzt.

Modern turbomachinery design is characterized by a tendency towards thinner, lighter and highly loaded blades, which in turn gives rise to increased sensitivity to flow induced vibration such as flutter. Flutter is a self-excited and self-sustained instability phenomenon that may lead to structural failure due to High Cycle Fatigue (HCF) or material overload. In order to be able to predict potential flutter situations, it is necessary to accurately assess the unsteady aerodynamics during flutter and to understand the physics behind its driving mechanisms. Current numerical tools used for predicting unsteady aerodynamics of vibrating turbomachinery components are capable of modeling the flow field at high level of detail, but may fail in predicting the correct unsteady aerodynamics under certain conditions. Continuous validation of numerical models against experimental data therefore plays significant role in improving the prediction accuracy and reliability of the models.   In flutter investigations, it is common to consider aerodynamically symmetric (tuned) setups. Due to manufacturing tolerances, assembly inaccuracies as well as in-service wear, the aerodynamic properties in a blade row may become asymmetric. Such asymmetries can be observed both in terms of steady as well as unsteady aerodynamic properties, and it is of great interest to understand the effects this may have on the aeroelastic stability of the system.   Under certain conditions vibratory modes of realistic blade profiles tend to be coupled i.e. the contents of a given mode of vibration include displacements perpendicular and parallel to the chord as well as torsion of the profile. Current design trends for compressor blades that are resulting in low aspect ratio blades potentially reduce the frequency spacing between certain modes (i.e. 2F &amp; 1T). Combined modes are also likely to occur in case of the vibration of a bladed disk with a comparatively soft disk and rigid blades or due to tying blades together in sectors (e.g. in turbines).   The present investigation focuses on two areas that are of importance for improving the understanding of aeroelastic behavior of oscillating blade rows. Firstly, aeroelastic properties of combined mode shapes in an oscillating Low Pressure Turbine (LPT) cascade were studied and validity of the mode superposition principle was assessed. Secondly, the effects of aerodynamic mistuning on the aeroelastic properties of the cascade were addressed. The aerodynamic mistuning considered here is caused by blade-to-blade stagger angle variations   The work has been carried out as compound experimental and numerical investigation, where numerical results are validated against test data. On the experimental side a test facility comprising an annular sector of seven free-standing LPT blades is used. The aeroelastic response phenomena were studied in the influence coefficient domain where one of the blades is made to oscillate in three-dimensional pure or combined modes, while the unsteady blade surface pressure is acquired on the oscillating blade itself and on the non-oscillating neighbor blades. On the numerical side, a series of numerical simulations were carried out using a commercial CFD code on a full-scale time-marching 3D viscous model. In accordance with the experimental part the simulations are performed using the influence coefficient approach, with only one blade oscillating.   The results of combined modes studies suggest the validity of combining the aeroelastic properties of two modes over the investigated range of operating parameters. Quality parameters, indicating differences in mean absolute and imaginary values of the unsteady response between combined mode data and superposed data, feature values that are well below measurement accuracy of the setup.   The findings of aerodynamic mistuning investigations indicate that the effect of de-staggering a single blade on steady aerodynamics in the cascade seem to be predominantly an effect of the change in passage throat. The changes in steady aerodynamics are thereby observed on the unsteady aerodynamics where distinctive effects on flow velocity lead to changes in the local unsteady pressure coefficients. In order to assess the overall aeroelastic stability of a randomly mistuned blade row, a Reduced Order Model (ROM) model is introduced, allowing for probabilistic analyses. From the analyses, an effect of destabilization due to aero-asymmetries was observed. However the observed effect was of moderate magnitude. / <p>QC 20130610</p> / Turbokraft

Today’s bridge design work in many cases demands a trustworthy dynamic analysis instead of using the traditional dynamic amplification factors. In this thesis a reliable 3D Bernoulli-Euler beam finite element model of the New Årsta Railway Bridge was prepared for thorough dynamic analysis using in situ bridge monitoring for correlation. The bridge is of the concrete box girder type with a heavily reinforced and prestressed bridge deck. The monitoring system was designed for long term monitoring with strain transducers embedded in the concrete and accelerometers mounted inside the edge beams and at the lower edge of the track slab. The global finite element model used the exact bridge geometry but was simplified regarding prestressing cables and the two railway tracks. The prestressing cables and the tracks were consequently not included and an equivalent pure concrete model was identified. A static macadam train load was eccentrically placed on one of the bridge’s two tracks. By using Vlasov’s torsional theory and thereby including constrained warping a realistic modulus of elasticity for the concrete without prestressing cables and stiffness contribution from the railway tracks was found. This was allowed by comparing measured strain from strain transducers with the linear elastic finite element model’s axial stresses. Mainly three monitoring bridge sections were used, each of which was modelled with plane strain finite elements subjected to sectional forces/moments from a static macadam train load and a separately calculated torsional curvature. From the identified modulus of elasticity the global finite element model was updated for Poisson’s ratio and material density (mass) to correspond with natural frequencies from the performed signal analysis of accelerometer signals. The influence of warping on the natural frequencies of the global finite element model was assumed small and the bridge’s torsional behaviour was modelled to follow Saint-Venant’s torsional theory. A first preliminary estimation of modal damping ratios was included. The results indicated that natural frequencies were in accordance between modelling and signal analysis results, especially concerning high energy modes. Estimated damping ratios for the first vibration modes far exceeded the lower limit value specified in bridge design codes and railway bridge dynamic analysis recommendations. / QC 20101124