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Conception optimale de structures cinématiques tridimensionnelles. Application aux mécanismes de transmission en rotation

Abstract : This work is about creation of preliminary design tools. They should be able to build admissible solutions from given specifications for initiating the design process (sketching and approximate dimensioning of part shapes).

In this connection, a design method is presented. It is particularly suitable for the class of rotative movement transmission mechanisms, with a linear structure, one degree of mobility and a constant ratio. The CASYMIR software (Conception Assistée de Systèmes Mécaniques de transmIssion en Rotation, which stands for « Aided design of rotative transmission mechanical systems » ) was implemented for illustrating the three-stage-design process :

At the topological synthesis stage, a creative algorithm generates the whole admissible mecanical solutions. It combines mechanisms taken from a mechanism database (gearings, belts, epicyclic gearings, joints, etc.) and eliminates bad combinations using design rules. Solution mechanisms are sorted in a preference order thanks to a multi-criterion or a fuzzy logic algorithm.

For pre-dimensional calculations, we introduce the notion of mechanism skeleton, which is a linear spatial representation of shaft lengths, distances between axis and angles of the mechanism. A geometrical model is constructed according to Denavit-Hartenberg model. Then it is optimized, which gives the best position and orientation of the mechanism stages for minimizing overall dimensions and verifying closure conditions.

During the last dimensional synthesis stage, the main dimensions of the mechanism are computed by integrating geometrical constraints (absence of collision between parts, geometric and kinematic continuity) as well as technological constraints (pressure criterion for gear teeth, speed ratio, etc.) in a global optimization problem.

Finally, the study of an industial speed reducer gives the opportunity to validate both the
software and the method.
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https://tel.archives-ouvertes.fr/tel-00006691
Contributor : Jean-Christophe Fauroux <>
Submitted on : Tuesday, August 17, 2004 - 5:27:04 PM
Last modification on : Thursday, March 11, 2021 - 10:18:02 AM
Long-term archiving on: : Friday, April 2, 2010 - 8:14:16 PM

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  • HAL Id : tel-00006691, version 1

Citation

Jean-Christophe Fauroux. Conception optimale de structures cinématiques tridimensionnelles. Application aux mécanismes de transmission en rotation. Mécanique [physics.med-ph]. INSA de Toulouse, 1999. Français. ⟨tel-00006691⟩

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