Cohen Assouline, Stéphanie (2005) Numerical simulation of machining at macroscopic scale: taking into account the workpiece deformations. PhD thesis Mécanique, ENSAM 2005ENAM0028.
Abstract
The idea to set general simulator of the mechanical part of machining has given its origin to this work.
The principal contribution of this work is the taking into account of workpieces for which the zone concerned with machining is flexible. This presence of deformations in the workpiece requires a precise definition of the removal of matter. This definition is based on a configuration known as material, where the practical realization of the simulation of machining is carried out.
In addition, the flexible workpiece being generally very thin, the removal of matter can modify to a significant degree the dynamic behaviour of the workpiece (loss of mass and stiffness). To be accurate, a simulation must then take into account this modification in a regular way in the course of machining. We show that this taking into account cannot be avoided in certain cases, and we propose a strategy limiting the numerical costs induced by this taking into account.
Another contribution of this work is the use of a different geometrical model, to represent the volume occupied by the workpiece than in previous studies of LMSP. With the geometric models of the workpiece used in previous works at LMSP (B-Rep model like the models used in CAO) many difficulties to achieve a sufficient reliability occured, in particular when the tool is passing many times on the same place (this is often the case in milling). The new adopted technique is that of the Z-buffer where the workpiece is modelled by dexels (set of "sticks" laid out on a regular matrix). This description makes it possible to simplify appreciably the algorithms of intersection while making them more robust. This new description led us to re-examine the interaction tool/workpiece and in particular the step of calculation of the cutting forces.
This work is implemented in the software Nessy, developed at LMSP. Simulations show the feasibility of our approach and its potential of analysis.
| Item Type: | PhD Thesis (PhD) |
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| Thesis Supervisor: | Coffignal, Gérard |
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| Date: | December 2005 |
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| Board of examiners: | Martin, Patrick and Hascoët, Jean-Yves and Rigal, Jean-François and Léon, J.c. and Le Calvez, C. and Lorong, Philippe and Coffignal, Gérard |
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| Ecole Doctorale: | ED 432 ECOLE DOCTORALE SCIENCES DES METIERS DE L'INGENIEUR |
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| Discipline: | Mécanique |
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| Collection (Fonds): | ENSAM |
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| Institution: | ENSAM |
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| Subjects: | 4. Materials Science, Mechanics and Mechanical Engineering |
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| Uncontrolled Keywords: | Simulation, Machining, Thin-walled pieces, Vibrations, Dexels, Intersection algorithms, Simulation, Usinage, Pièce flexible, Vibrations, Dexels, Algorithmes d’intersection |
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