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In this thesis the dynamic behavior of a scroll compressor with piping system is studied using numerical and experimental tools in order to improve the knowledge in numerical modeling. A multi-body dynamics analysis is firstly performed by completing an existing finite element model to obtain a complete compressor. The model inputs are chosen to best represent the real conditions applied to the compressor. Then, the results of this first model are used to create excitations in a second model which studies the harmonic response of the system. A modal analysis must be done to obtain the different natural frequencies of the system and then determine how it will react to these excitations. A second harmonic analysis is realized using the same excitations but calculated analytically. The comparison of the two harmonic responses leads to similar results which allows to affirm that the analytical calculations are sufficient to have a consistent harmonic response and that a multi-body analysis is not essential in this case. Finally, experimental modal analysis and vibration tests are conducted on an experimental structure in order to measure eigenfrequencies, accelerations and strains at several points of the real system and compare them with numerical results. It appears that the experimental accelerations are up to three times lower than the numerical ones because the multi-body model does not start from a static equilibrium and therefore, under the application of gravity, it is dropped on the grommets and bounces on them. The simulation is too short to dampen this phenomenon which means that the model is not yet in a steady state. These excessive accelerations imply too high displacements and thus lead to high strains which explains the factor 10 between the numerical and experimental strains. Lastly, some points of possible improvement are detailed for future works.

Ingénierie, informatique & technologie > Ingénierie mécanique

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The S-bos floating wind platform, designed by BlueNewables, is a spar-type concept that intends to reduce the installation and transportation and maintenance costs while providing outstanding stability under harsh wind and waves regimes.
The main objective of this master thesis is the so-called coupled assessment of the S-bos platform.
The implementation is to be performed in an aero-hydro-servo-elastic numerical model. Modelling the S-bos platform poses challenges product of the existence of diffraction, inertial and viscous forces for different wave regimes. Neither Morison’s equation nor potential flow theory can reliably predict the dynamic response of the structure to the wave loading alone. The floating substructure is a combination on Morison and Froude Krylov elements that need to be properly considered on the numerical model.
Furthermore, the numerical models will be validated against experimental scaled tests.
The 10MW wind turbine and the tower will be modelled considering the elasticity of tower and blades. The control of the wind turbine will be tuned to minimize the pitch motions of the floater and to avoid the negative damping effect.
Once the fully coupled model is set, the analysis will be performed considering a selection of critical load-cases following international standards on floating wind platforms design.

Ingénierie, informatique & technologie > Ingénierie mécanique

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This work presents the analyses of different structures of a cruise ship to find the correlation between the vibrational behavior performed by finite element method simulations and measurements on-site. The structures include deck areas in the ship under construction and real scale models of passengers’ cabins. For the decks areas, there is a comparison of two different applications of the finite element method in Ansys: Classic and Workbench.
A modal analysis was performed on two decks’ sections in the area where passenger cabins will be installed. The differences between Ansys Classic and Workbench go from less than 1% to up to 20% depending on the closeness of the mesh size. Not all the mode shapes were easy to identify and not all of them visually match; the main differences between the models could be due to the different types of elements used to represent the structure’s behaviour and the distribution of those elements over the decks’ model. In the correlation with measurements from the test, there is not a clear tendency neither for Ansys Classic nor for Ansys Workbench to better fit with the measurements results, however, both show good results in terms of the range of frequency. Some parameters could be influencing the resultant frequencies and have not been considered in the models.
Then, the modal analysis of a prototype of a passenger’s cabin “Ramsess” is performed. At the time of the test, only the steel structure of the cabin was built, then, the model was formed by girders and pillars. The results of this analysis show a good correlation between the finite element model and the measurements, the maximum difference between the natural frequencies is 5%, and the mode shapes were easy to identify. It was possible to test two different support conditions to check the one which better represents the real structure, it was found that it depends on the main direction of the deformation.
Finally, the vibrational response of a cabin model is estimated by applying an external random excitation and compared with the finite element simulation. The model for finite element analysis was developed with a medium level of details, including the main steel structure, but excluding some non-structural parts. The results were compared in three points of the cabin’s balcony showing a good correlation in magnitude and a maximum difference in the peak’s frequencies of 16% for one of the points. In the other two points, the results do not correlate quite well probably due to an inaccurate representation of the model, not only by exclusion of some elements but also for the support condition.

Ship vibration --- Ingénierie, informatique & technologie > Ingénierie mécanique

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Heat engineering --- Power (Mechanics) --- Thermodynamics --- Thermique --- Énergie mécanique --- Thermodynamique

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Ce travail a été effectué dans l'entreprise AB InBev de Jupille-sur-Meuse dans le but d'améliorer l'efficacité d'une ligne d'embouteillage de son site. Pour ce faire, l'application de la théorie de la Line Balance Optimisation a été mise en place sur la ligne JB1

L'objectif de toute ligne d'embouteillage est de faire en sorte que la machine critique de la ligne, à savoir la machine la plus lente du cycle, fonctionne le plus longtemps possible et qu'en cas d'arrêt, elle puisse redémarrer au plus vite. Cet objectif est atteint grâce au régime de survitesse des machines sur la ligne et à l'aide de tables d'accumulations entre ces machines pour minimiser l'impact des pannes.

Pour ce faire, un état de la ligne a dû être réalisé au moyen d'un audit. Celui-ci a consisté notamment à mesurer les survitesses réelles des différentes machines de la ligne afin d'identifier si celles-ci suivaient une représentation classique en V, synonyme de ligne balancée.

Pendant cet audit, un ensemble de problèmes sur la ligne a pu être mis en évidence. Certains de ces problèmes ont pu être rapidement résolus tandis que d'autres ont permis d'identifier les causes d'autres problèmes.

Compte tenu des résultats de cet audit, l'accent s'est porté sur deux aspects : une meilleure signalisation des pannes aux opérateurs et un rétablissement du V-graphe au moyen d'une implémentation mécanique de répartiteur casiers.


Pour conclure, l'impact financier annuel des différentes actions mises en oeuvre a été estimé.

Line Balance Optimisation --- AB InBev --- Ingénierie, informatique & technologie > Ingénierie mécanique