This thesis describes a project of a mobile stage device that will be used for a concert tour of Lucie. The first part characterizes the given task and expounds description and function of the device itself. The second part focuses on the design concept of supporting frames. This is followed by design and calculation of all mechanisms, actuators and construction of individual moving parts of a sliding and lifting platform. The last part verifies stability of the whole construction in accordance with appropriate standards. The thesis also contains technical documentation, which is to be found in appendix.

Mobile Miner 40V is a machine used for rock excavation and developed by Epiroc. This machine is equipped with a large cutter wheel to perform the excavation. After a test run, some surfaces associated with bearings within the cutter wheel were found to be damaged due to scuffing - severe sliding wear. There is a static load applied to the surfaces due to gravity. However, the reason for this damaged issue was believed that there is a large dynamic load applied to the surfaces during the excavation. This dynamic load was not found in a previous FE model used to verify safety issues. Therefore, a new FE model that is more in line with reality, and a failure analysis were required. Additionally, a feasibility study for a cutter wheel with a larger dimension was also needed since a larger cutter wheel is desirable. Firstly, wear mechanisms were reviewed, and some theories were chosen to analyze the damaged issue. Since it was unknown whether the surfaces were well-lubricated or not, both cases were investigated. The Archard wear equation was used to analyze the poor-lubricated situation, while the lubrication number and the Reynolds equation were used to analyze the well-lubricated case. Secondly, contact mechanisms between the surfaces were also investigated. The investigation of the contact mechanisms involved several theories, such as the Hertzian contact theory and the impact load factor. Besides these theoretical analyses, a numerical analysis was performed. Lastly, a new FE model was established in Ansys. Both the cutter wheel which was subjected to scuffing(existing cutter wheel), and the cutter wheel with a larger dimension(larger cutter wheel) were analyzed by the use of the new FE model. The maximum and minimum wear rates obtained by the Archard wear equation are approximately 1.9・10-2mm3/m and 4.8・10-3mm3/m, which are considered as a completely unacceptable level in engineering applications. The maximum and minimum critical loads obtained by the Reynold equation are approximately 1.8kN and 24.8kN, which both are larger than the static load applied to the surfaces. The maximum and minimum critical mean contact pressures obtained by the lubrication number are approximately 65MPa and 240MPa, which both are larger than the mean contact pressure generated by the static load. No evidence shows that there is a large dynamic load applied to the surfaces during the excavation. The largest possible contact pressure on the bearings in the existing cutter wheel is very close to the limit of severely damaged. The largest possible contact pressure on the bearings in the larger cutter wheel is believed to exceed the limit of severely damaged. The previous assumption that the surfaces were damaged due to a large dynamic load was wrong. The obtained results support that the surfaces were only subjected to a static load and were damaged due to inadequate lubrication. The existing cutter wheel is operated safely with the current load cases. However, the forward thrust force is suggested to decrease when the cutting angle is large. There is a high risk if the larger cutter wheel is operated with the current load cases.

Journal bearings are being used in various locations of an internal combustion engine. They contribute to a large portion of total engine friction and lowering it means a significant contribution to CO2 reduction. Operating under heavy loads, journal bearings are often subject to mixed regime of lubrication where a part of bearing load is carried by asperities. This necessitates accurate modelling of asperities contact in order to get more realistic predication of friction losses in journal bearings contact. The evaluation method at Scania couples 3D confocal measurement of bearings’ surface roughness to a Multi-body Dynamic Analysis of journal bearings lubrication utilizing AVL EXCITE. During running-in, asperity peaks are reduced due to wear caused by metal-to-metal contact resulting in change of bearing surface profile and different contact zones in axial and circumferential direction. The aim of this thesis is to include these different contact zones and run-in wear profile of the bearing to the existing evaluation method at Scania to simulate run-in effects more precisely. Surface measurements were made on a run-in big end bearing surface at edges, center and region after oil hole. From these measurements, using the existing Local Scale Model at Scania, asperity pressure curve and flow factors were obtained, which were used to perform AVL EXCITE big end bearing simulations with multiple surface contact patches. The results show that the inclusion of multiple surface patches and run-in wear profile lead to a significant change in distribution and also magnitude of bearing performance parameters e.g. pressure, friction losses, clearance height. / Glidlager är en av de mest använda komponenterna i motorer. De bidrar till en stor del av motorns totala friktion och en minskning av denna bidrar i hög grad till minskade utsläpp av CO2. Glidlager som arbetar under hög last utsätts ofta för blandfilmssmörjning där en del av lasten bärs av mekanisk kontakt mellan ytornas asperiteter. Detta kräver en noggrann modellering av asperitetskontakter för att få en realistisk prediktion av friktionsförluster i glidlager.Utvärderingsmetoden på Scania kopplar ihop 3D-mätning av lagrets ytfinhet i ett konfokalmikroskåp med en dynamisk tribologiberäkning i MBS-programvaran (Multi Body Simulation) AVL Excite.Under inkörning nöts asperiteterna ner på grund av metallkontakten mellan ytorna vilket påverkar lagerytans profil och ger olika kontaktzoner i axiell och periferiell riktning.Syftet med examensarbetet är att inkludera de olika kontaktzonerna och lagrets profil efter inkörning i Scanias befintliga utvärderingsmetod i syfte att noggrannare kunna simulera inkörning av lagren.Ytfinhetsmätningar utfördes med ett konfoklamikroskop på ett inkört vevlager vid kanterna, i mitten och i närheten av oljehålet.Med hjälp av dessa mätningar och en av Scanias befintliga kontaktmodeller beräknades asperitetstryck och flödesfaktorer vilka användes för att utföra vevlagerberäkningar i AVL Excite med olika kontaktegenskaper i olika regioner.Resultaten visar att införandet av regioner på lagerytan med olika lokala kontaktegenskaper och lagerprofil efter inkörning ger en signifikant förändring av såväl storleken som fördelningen av olika lagerresultat såsom till exempel lagertryck, friktionsförluster och oljefilmstjocklek.

Total ankle replacement (TAR) implants are an effective option to restore the range of motion of the ankle joint for arthritic patients. An effective tool for analyzing these implants’ mechanical performance and longevity in-silico is finite element analysis (FEA). ABAQUS FEA was used to statically analyze the von Mises stress and contact pressure on the articulating surface of the bearing component in two newly installed fixed-bearing total ankle replacement implants (the Wright Medical INBONE II and the Exactech Vantage). This bearing component rotates on the talar component to induce primary ankle joint motion of plantarflexion and dorsiflexion. The stress response was analyzed on this bearing component since it is made of the least strong material in the implant assembly (ultra-high molecular weight polyethylene (UHMWPE). This bearing component commonly fails and is the cause for surgeon revisions. Six different FEA models for various gait percentages during stance (10%, 20%, 30%, 40%, 50%, and 60%) were created. They varied in magnitude of the compressive load and the ankle dorsiflexion/plantarflexion angle. This study captured the variation in stress magnitudes based on the portion of the stance phase. The results indicated that the stress distribution on the articulating surface increased as compressive load increased, and the largest magnitudes occurred at high dorsiflexion angles (15-30°). The von Mises stress and contact pressure tended to occur in regions where the thickness of the bearing was the least. Additionally, high contact pressures were examined in areas near the talar component's edge or at the bearing's edges. To the author’s knowledge, this is the first study available to the research community that analyzes the Vantage implant with FEA. This study lays an essential foundation for future researchers in presenting a thorough literature review of TAR and for a simple model setup to capture the stress distributions of two TAR implants. This study provides valuable information that can be beneficial to medical company designers and orthopedic surgeons in understanding the stress response of TAR patients.

No description available.

In einer Einleitung werden verschiedene Möglichkeiten der Kopplung unterschiedlicher physikalischer Domänen diskutiert. Begriffe wie Kopplung auf Systemebene über Terminals und auf Feldebene über Lastvektor oder Matrixkopplung werden zugeordnet. Wie diese Kopplungsmöglichkeiten sich in der ANSYS Simulationsumgebung wiederfinden, wird aufgezeigt. Am Beispiel eines Akuators wird erläutert, welche physikalischen Domänen gekoppelt betrachtet werden müssen, um die hier vorhandenen temperaturabhängigen Materialeigenschaften zu berücksichtigen. In einem Beispiel zu einer Steckverbindung wird aufgezeigt, wie eine vom Kontaktdruck abhängige Leitfähigkeit berücksichtigt wird und Ergebnisse aus dieser Simulation werden diskutiert.

This diploma thesis deals with hot-formed helical compression springs. The first part of the thesis describes related problems and determines market potential. Following theoretical part describes the influence of contact line on behaviour of springs and compares it with normative regulations. Methods suitable for determination of helix shape are covered in the next part. The last part focuses on practical measurement, in which the change of helix shape during manufacture was observed. The main output of this diplomat thesis is suggestion of measures that should contribute to both optimization of manufacture and verification of FEM model.

Ce travail est une contribution à l'étude du comportement des joints en translation. Un modèle numérique, basé sur la théorie inverse, est développé pour en prédire les performances. La principale contribution consiste dans le traitement des effets hydrodynamiques liés à la région d'entrée du contact. Les résultats numériques sont ensuite validés par comparaison avec lesmesures expérimentales. Ces dernières sont obtenues sur un dispositif original, conçu et réalisé au laboratoire INOE 2000 IHP de Bucarest. Ce banc reproduit les conditions réelles de fonctionnement d'un joint hydraulique et permet de mesurer la force de frottement à pression et vitesse constantes. La comparaison des résultats numériques et expérimentaux a été effectuéepour un joint de tige en forme de "U" à des pressions de service comprises entre 4 MPa et 20 MPa et pour deux vitesses de translation. Dans un premier temps, on a idéalisé le problème en considérant que les surfaces en contact tige-joint sont lisses. Si l'épaisseur du film est supérieure à la rugosité de la tige, les résultats numériques qu'on a obtenus sont en bonne corrélation avecles résultats expérimentaux. Dans le cas contraire, le modèle doit être amélioré. Cette amélioration a été entreprise de manière originale. En effet, la théorie inverse est appliquée à la distribution de pression statique du contact obtenue à partir de la simulation par éléments finis de l'assemblage d'un joint rugueux et d'un arbre lisse. La rugosité moyenne (Ra) de la surface dujoint en contact avec la tige a été choisie égale à la rugosité moyenne mesurée du joint étudié. Les résultats ainsi obtenus améliorent sensiblement la corrélation avec les mesures e / This work is a contribution to the study of reciprocating seals behavior. A numerical model, based on the inverse hydrodynamic lubrication theory, is developed to predict their performances. The main contribution consists in the treatment of the hydrodynamic effects in the entry region of contact. The numerical results are validated by comparison with experimentalones, obtained on an original experimental device, design and conceived in the laboratory INOE 2000 IHP of Bucharest. This bench reproduces actual operating conditions of a hydraulic seal and measures the friction force at constant pressure and speed. The comparison of experimental and numerical results was carried out for a "U" type rod seal at different operating pressuresvarying from 4 MPa up to 20 MPa and for two reciprocating speeds. Initially, we idealized the problem by assuming that the surfaces in contact are smooth. The numerical results obtained are in good correlation with experimental ones if the film thickness is greater than the rod roughness. Otherwise, the model must be improved. This improvement was undertaken in an original way. The inverse lubrication theory is applied to the dry frictionless contact pressure distribution, obtained from a FEM simulation of a rough seal and a smooth rod assembly. The average roughness (Ra) of the seal surface in contact with the rod is chosen equal to the measured average roughness of the studied seal. The results obtained significantly improve the correlationwith experimental measurements. The roughness distribution on the entry region of contact appears to have an important influence on the numerical results.

This diploma thesis focuses on the issue of a wear of a railway wheel and a rail. The wear of the components depends on a number of parameters including the contact stress, the contact pressure and the contact surface dimensions. Among the factors determining these parameters belongs primarily the wheel driving gauge, the rail profile and the load of the contact area. Furthermore, the material from which the wheels and rail are made, the roughness and hardness of the functional surfaces and the residual stress in the material have a significant impact on the wear. All the parameters mentioned above are designed for the production of the railway wheels and rails and therefore they meet the standards for the production of these components. However, the existence of the changeable parameters has also a significant impact on the wear. These parameters include the presence of contaminants, or lubricants in contact, the changing driving gauge due to the wear, the slip ratio or the friction coefficient. With the wear being an inevitable process during the application it cannot be eliminated but only controlled. Applying the lubricant into the contact when passing through the arc in order to achieve an ideal coefficient or the maintenance grinding for restoring the driving gauge can serve the purpose. If properly optimized, the importance of the wear research lies in the financial savings. Being the crucial factor for optimization of the intervals between the maintenance grinding, the research is also beneficial. A high-quality wear prediction can be seen as the key field in order to increase the safety of the railway vehicles operation as well. Therefore, the wear research is made using several methods, such as the computational models, the multi-body dynamics software and the technical experiments. This thesis introduces a conceptual design of the test, enabling the wear research via experimental approach. The final device is capable of a simulation of both volume and fatigue wear during the states the railway wheel and railway undergo including riding on the straight track, passing through an arc or a wheel slip during braking.

Die Dissertation beschäftigt sich mit der grundlagenorientierten Untersuchung reibdauerbeanspruchter Stahl-Kontakte und deren Festigkeitsbewertung. Die Besonderheit bei der Bewertung reibdauerbeanspruchter Kontakte stellt die zusätzlich zur spannungsmechanischen Beanspruchung vorliegende tribologische Beanspruchung des Werkstoffes dar. Die ursächlich auf eine Anrissinitiierung in der Bauteiloberfläche zurückzuführende niedrigere Ermüdungsfestigkeit reibdauerbeanspruchter Bauteilverbindungen, zeigt sich in Abhängigkeit des Fugendrucks, des Schlupfes und des Werkstoffes. Basierend auf den genannten Einflussgrößen konnte in der vorliegenden Arbeit ein Berechnungsverfahren erarbeitet werden, welches eine betriebssichere Auslegung reibdauerbeanspruchter Fügeverbindungen ermöglicht. Das Verfahren basiert auf dem örtlichen Konzept der FKM-Richtlinie „Rechnerischer Festigkeitsnachweis für Maschinenbauteile“ und implementiert den Schadenfall der Reibdauerermüdung durch einen Oberflächeneinflussfaktor, dem sogenannten Reibkorrosionsfaktor. Die tribologischen Beanspruchungsparameter Schlupf und Fugendruck werden dabei über eine Worst-Case-Betrachtung berücksichtigt. Durch eine von der Zugfestigkeit des Grundwerkstoffes abhängige Darstellung des Reibkorrosionsfaktors, konnte darüber hinaus eine systemspezifische Berechnung der Ermüdungsfestigkeit erreicht werden. Die Validierung des Berechnungsverfahrens erfolgte an einer Pleuelverbindung. / The doctoral thesis investigates basically the fretting fatigue strength of steel contacts and their strength assessment. Especially the tribological loading conditions which are present at the contact surface cause a specific method of the strength assessment of joined contacts. In this context, the lower fatigue strength of component connections under tribological loading conditions, which is the result of crack nucleation at the component surface, depends on the contact pressure, the slip and the basic-material. Based on these parameters, a calculation method was developed in the present study which allows a reliable design of component connections under fretting conditions. This method is based on the local concept of the FKM-guideline 'Rechnerischer Festigkeitsnachweis für Maschinenbauteile' and introduces the fretting fatigue failure mechanism by a surface factor, the so-called fretting factor. These fretting factors are calculated empirically and based on a worst-case approach of the tribological parameters slip and contact pressure. Furthermore it is possible to determine the fretting factor according to the tensile strength of the basic-material. As a result of this, it is possible to calculate the system-specific fretting fatigue strength of joined steel-components. The improved calculation accuracy of the strength assessment was validated on connecting rods.