Ce travail de thèse se concentre sur l’étude du comportement dynamique des tubes minces durant leur usinage par tournage et notamment sur la survenue du broutement régénératif. L’étude de l’usinage de ce type de pièce est pertinente car ces pièces font l’objet d’une large diffusion dans divers domaines industriels tels que la construction aéronautique (notamment moteurs), la construction navale, la production de fusées. Ces pièces ayant une faible rigidité, il est fréquent que des vibrations indésirables se produisent en cours d’usinage. Il est donc intéressant d’être à même de les prédire pour les éviter.L’approche proposée vise à permettre un choix rapide et efficace des conditions de coupe, et notamment des profondeurs de passe, pour cette opération d’usinage. Pour cela nous proposons de mettre en place un modèle mécanique analytique du tube (modèle de coque mince utilisant un nombre réduit de degrés de liberté) de manière à réduire les coûts numériques et à faciliter l’analyse du phénomène. L’impact de la taille du modèle sur les résultats est étudié (nombre de formes propres) ainsi que de la prise en compte de l’enlèvement de matière (évolution du comportement dynamique) et du déplacement de l’outil. Afin de valider l’approche une expérience a été mise en place et est également présentée dans ce mémoire. / This work focuses on the study of the dynamic behavior of thin tubes during their machining by turning and gives particular emphasis on the occurrence of regenerative chatter. The study of machining of this type of workpiece is relevant because they are widely used in various industrial fields such as aircraft construction (including engines), shipbuilding, rocket production. As these parts have low rigidity, it is common that undesirable vibrations occur during machining. It is therefore of interest to be able to predict them in order to avoid them.The proposed approach is designed to enable a fast and efficient selection of cutting conditions, including cutting depths for this machining operation. We thus propose to elaborated an analytical model for the dynamics of the tube (thin shell based model using a reduced number of degrees of freedom) to reduce the numerical costs and to facilitate the analysis of the phenomenon. The impact of the size of the model on the results is studied (number of shape functions), as well as the impact of material removal (evolution of the dynamic behavior) and of the motion of the tool. An experiment, presented in this thesis, was also set up in order to validate the approach.

This thesis concerns the technological processes of machining of thin-walled parts and the modification of said processes in dependence on the following interopera-tive measurement of the real dimensions of these parts. Within the theoretical part a research study of technological possibilities of measuring thin-walled parts and principles of probe programming are presented. In the main practical part of the the-sis a proposal of an experiment is described, which tests the individual technologi-cal steps and their influence on the quality of a prototype of the produced thin-walled part. Numerical (NC) codes are created using parametric programming, which are then used during the realization of the experiment itself. In the conclusi-on there are presented and discussed the results of measuring of the machined surfaces and the influence of correction paths, which should help to achieve a mo-re accurate production according to given dimensions. This experiment, however, has not met the expected results. That is why new procedures have been designed in order to create said paths, which can be used in a future realization of this expe-riment.

Master‘s thesis deals with sawing of the thin-walled parts with high speed steel slitting saw. At first the most used conventional and unconventional possibilities of materiál cutting are described by a form of search. The next chapter describes forces arising from splitting saw machining, including their dependence on a specific cutting force, a chip cross section and a engagement angle. The second part of the thesis deals with the technological improvement of the cutting process, where three possible solutions are considered – geometry of the cutting tool, PVD coating deposition of the cutting tool and process fluid change. In the experimental part non coated slitting saw with burrs, non coated deburred slitting saw and coated slitting saws are compared. Used coatings were Ti(C,N), Cr-Al-Si-N, Al-Cr-B-N, and TripleCoating Cr, which is consisting of three layers TiN + (Al,Ti)N + Cr-Al-Si-N. The experiment has shown that the cutting forces inceases as the edge radius and wear level of the cutting tool increases. Coated cuttung tools has shown lower differences between the first and the last cut. Slitting saws have been also used in real cutting process to verify experimental results.

Thesis is concerned with modeling fluid dynamics and computing wind load on thin-walled structure of cooling tower. Two models for computational fluid dynamics are presented – one with singleton cooling tower and second with group of four cooling tower. Thesis includes also a structural model of cooling tower and methodology of wind load transfer is presented.

KELČA Daniel: Welding of thin-walled pipe The project, elaborated during the engineering study, field of study M-VTM (Production technology and industrial management) deals with welding of thin-walled pipes Cats in practise. There are methods of WIG and microplasma welding compared. The suggested basic material is corrosion-resistant ferritic steel X2CrMoTi18-2 (1.4521; AISI 444). Welding runs continuously and depends on the demanded length of the thin-walled pipe. The tests of the weld were designed on the basis of a literary study. They should help us together with the economic evaluation to assess the two methods.

The diploma work focuses on the proposal of formula car support frame type alternative designed for international students´ competition Formula Student. As a first is this competition shortly described. Following basic information about possible support frame in competition, the rules description for the frame from thin-walled profiles as well as for composite structure. As the other are shown the most used material types by the tube frames. Continues the practical (design) part of the work. The work continues in construction/design part. Here are mentioned the requirements for the frame creating, calculation of each torsion strength and construction proposal including creating the analysis model. In the final part is realize the simulation in FEM program and simply described the alternative proposal together with the evaluation.

The master’s thesis is focused on the possibilities of machining lines of the company Vernet – Behringer. The theoretical part is a brief inclusion of the control system ProNC2 between selected commercially available control systems and are compared ways of programming CNC machine tools. On the machine tool of company Vernet – Behringer are processed mainly thin-walled components, that is why is part of the work focuses on the issue of machining thin-walled parts, the distribution of deflection tools and machined parts. The next part of thesis deals with the design and processing of technical documentation for the machined model part. The practical part deals with the possibilities of the machine and method of programming the control system ProNC2. Programming and practical production on machine were proceeded in company SSI Schäfer s.r.o. The work is focused on practical verification of the production process using simulation and production itself. Finally, it was performed technical - economic evaluation of production.

The aim of this thesis is to create the proposal and expansion of knowledge in the field of experimental measurement of force load when milling thin-walled parts made of aluminum alloy monolithic cylindrical shank cutter of cemented carbide (hereinafter referred to as CC). It also discusses the theoretical analysis of the forces generated during milling, and practical approaches to their measurement experiments. This work also deals with the analysis of aluminum and its alloys. The next chapter describes the appropriate strategy for the machining of thin-walled components including defining the problems, that can complicate machining thin walls. The practical part deals with prediction and a following suggestion of the experiment measuring the power load. The last section is devoted to the practical implementation of the measurement of forces during the milling of thin-walled parts with subsequent evaluation and comparison of strength for the record selected from CC carbide tools, including evaluation of roughness parameters.

<p>U ovoj disertaciji, izvršena su teorijska i eksperimentalna istraživanja dinamičkog onašanja jezgra visokih zgrada. Model je zasnovan na Vlasovoj teoriji tankozidnih nosača, kao i na metodi prenosnih matrica. Jezgro se tretira kao tankozidni nosač otvorenog poprečnog preseka, koji je na dnu uklješten u temeljnu ploču, dok je na vrhu&nbsp; slobodan.&nbsp; Duž&nbsp; ose&nbsp; smicanja,&nbsp; jezgro&nbsp; je&nbsp; podeljeno&nbsp; na&nbsp; čvorove&nbsp; u&nbsp; nivoima spratova&nbsp; u&nbsp; kojima&nbsp; su&nbsp; redukovane&nbsp; mase.&nbsp; Poseban&nbsp; naglasak&nbsp; je&nbsp; stavljen&nbsp; na&nbsp; analizu uticaja poprečnih greda, međuspratnih ploča, kao i načinu oslanjanja međuspratnih ploča po spoljašnjoj konturi na dinamičke karakteristike jezgra. Razvijeni&nbsp; numerički&nbsp; postupak&nbsp; je&nbsp; primenjen&nbsp; na&nbsp; armiranobetonskom&nbsp; jezgru petnaestospratne zgrade, koja je analizirana ranijeu radovima mnogih autora. U tu svrhu korišćen je računarski program TWBEIG, napisan primenom Visual Fortran programskog jezika. Analize su urađene i MKE, a dobijeni rezultati su upoređeni. Vrednosti sopstvenih frekvencija pokazuju dobro slaganje.<br />Ovaj rad daje detalje i o eksperimentalnoj studiji&nbsp; u kojoj se primenjuje pleksiglas model u cilju pružanja eksperimentalnih podataka zaproveru tačnosti i pouzdanosti numeričkih&nbsp; rezultata.&nbsp; Dobijeni&nbsp; rezultati&nbsp; su&nbsp; takođe&nbsp; upoređeni&nbsp; sa&nbsp; rezultatima dobijenim TWBEIG računarskim programom, kao i MKE.<br />Predstavljeni&nbsp; numerički&nbsp; metod&nbsp; nudi&nbsp; solidnu&nbsp; osnovu&nbsp; za&nbsp; formiranje&nbsp; jednostavnog modela&nbsp; proračuna,&nbsp; a&nbsp; ipak&nbsp; obezbeđuje&nbsp; odgovarajući&nbsp; nivo&nbsp; preciznosti.&nbsp; Predloženi postupak&nbsp; može&nbsp; biti&nbsp; korišćen&nbsp; i&nbsp; u&nbsp; fazi&nbsp; prethodne&nbsp; analize&nbsp; zgrade,&nbsp; kao&nbsp; i&nbsp; u&nbsp; fazi konačnog projektovanja.</p> / <p>In this dissertation, a theoretical and experimental study of the dynamic behaviour<br />of&nbsp; the&nbsp; tall&nbsp; buildings&nbsp; core&nbsp; was&nbsp; carried&nbsp; out.&nbsp; The&nbsp; model&nbsp; is&nbsp; based&nbsp; on&nbsp; the&nbsp; Vlasov&#39;s<br />theory of thin-walled beams and the transfer matrixmethod. The core is treated as<br />a thin&nbsp; wall-walled, open cross section cantilever beam. Along the shear axis the<br />core&nbsp; is&nbsp; divided&nbsp; into&nbsp; nodes,&nbsp; in&nbsp; the&nbsp; level&nbsp; of&nbsp; the&nbsp; floors,&nbsp; in&nbsp; which&nbsp; the&nbsp; masses&nbsp; are<br />reduced.&nbsp; Special&nbsp; emphasis&nbsp; was&nbsp; given&nbsp; to&nbsp; the&nbsp; analysis of&nbsp; the&nbsp; influence,&nbsp; of&nbsp; lintel<br />beams,&nbsp; floor&nbsp; slabs,&nbsp; as&nbsp; well&nbsp; as&nbsp; the&nbsp; type&nbsp; of&nbsp; restraints&nbsp; along&nbsp; the&nbsp; outer&nbsp; edge&nbsp; of&nbsp; the<br />floor slabs, on the dynamic characteristics of the core.<br />The&nbsp; developed&nbsp; numerical&nbsp; procedure&nbsp; was&nbsp; applied&nbsp; to&nbsp; the&nbsp; fifteen-storey&nbsp; reinforced<br />concrete core tall building, analyzed previously inthe papers of many authors. For<br />this&nbsp; purpose,&nbsp; the&nbsp; computer&nbsp; program&nbsp; TWBEIG&nbsp; was&nbsp; used, written&nbsp; using&nbsp; Visual<br />Fortran programming language. The analyses were also performed with FEM and<br />subsequently the results were compared. The values&nbsp; of natural frequencies show<br />significant agreement. This&nbsp; paper&nbsp; presents&nbsp; details&nbsp; about&nbsp; the&nbsp; experimental&nbsp; study&nbsp; which&nbsp; applies&nbsp; the plexiglas model in order to provide experimental data to verify the accuracy and reliability of the numerical results. The results are also compared with the results obtained with the TWBEIG computer program, as well&nbsp; as with FEM. The values of frequencies show reasonable agreement.<br />The proposed numerical&nbsp; method offers a solid base&nbsp; for the creation of a&nbsp; simple<br />calculation model, yet provides the appropriate level of precision. It can be either<br />used for preliminary analysis or for the final design.</p>

In design of an aircraft structure, the great emphasis is placed on achieving high weight efficiency. This thesis is focused on the stress analysis of the spars with thin web with or without web openings, which is one of the most important parts of the airplane structures. In comparison with traditional spars or beams, which are widely used in civil engineering applications, the design of the beam with thin web is more complicated. Thesis contains useful information for analytical calculation of this type of spars and its verification using finite element method and experimental measurement.