Etude de la propagation des erreurs mecaniques dans les assemblages grâce a une approche vectorielle basee sur les torseur

It is a historical fact that mechanisms are sensitive to their geometrical errors. These errors affect fabrication costs and often lead to unpredictable performance variations.;Some studies have been conducted on the effects of mechanical error accumulation. A lot of them are based on differential computation, although we have observed difficulties in their application in the analysis of mechanical errors and clearances. For this reason, we propose a new mathematical model to facilitate the analysis of clearances and mechanical errors in 3D mechanisms. In addition, this new model is appropriate for the computation analysis of mechanical errors.;Our new mathematical model is based on the screw theory and the vectorial exponential mathematics. A good understanding of some factors is essential to a valid mechanical errors analysis. These factors include geometrical errors, gaps, superficial deformations, volumic deformations and external forces acting on the mechanism.;The methodology validation is realized using the four bar linkage equation generators. We calculate the output error knowing the dimensional errors of each bar. These results confirm the validity of the new methodology. A mechanical speed variator is analyzed in order to demonstrate practical use of the new methodology.;To conclude, this thesis proposes a new methodology based on some vectorial theories used to analyze mechanical errors accumulation problems. (Abstract shortened by UMI.).