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Colloque avec actes et comité de lecture. Internationale.; International audience; The development of complex products is based on the exploitation of powerful Digital Mock-Up (DMU). Indeed, the three-dimensional geometric modeling of mechanical components constitutes an indispensable activity for the design. Computer-aided design (CAD) tools allow faithful and accurate representation of the product shape. This shape is the basic support used in the design phase and subsequent processes. In order to satisfy customer needs and ensure the best ratio price-quality, the geometric definition evolves, i.e., changes are made to the product shape according the product life cycle. Different models used and maintained by the specialists must also evolve in a coherent way. In fact, this evolution impacts the technical data specific to each discipline, as manufacturing , calculation and assembly models. Thus, for each contribution of a multidisciplinary participant, the geometric model data accumulate. This conducts industrial companies to retain and reuse data corresponding to reliable and approved products. The company knowledge and experience are capitalized as well as skills are better exploited. The proposed work in this paper proposes a tool for comparing geometric models. The comparison is founded on two main steps. The first step constitute an aggregation and filtering step. The studied model is selected as a reference one. Similar models are automatically determined according to the geometric information of CAD entities. The second step is based on geometric entity characteristic as comparison criterion to refine results. The entity identity comprises the Boundary Representation (B-Rep) model. The proposed tool is required a comparison between the studied model and the library of models already realized and approved by the company as well as to choose the most similar product. This choice allows to take advantage of acquired experiences as cost of production, problems encountered, etc. Several services will benefit from the difference characterization based on geometric information: the engineering to standardize the components, using similar models for calculation or manufacturing, etc. Otherwise, the proposed tool allows to reduce production time that decreases product cost.

Colloque avec actes et comité de lecture. Internationale.; International audience; In the digital mock-up, parts and assemblies are used in ideal configurations. In fact, tolerances are represented as annotation on the CAD model and tolerances stack-up is not considered during the optimization of mechanical system assemblability and F.E Analysis. Then, the improving of the numerical model requires consideration of tolerances in the CAD model. An approach to incorporate dimensional and geometrical tolerance in CAD model is developed. Indeed, models, that allow obtaining assemblies with defects, are realized. In a bottom-up design process (component-to-assembly), the proposed model founds components with defects allowed by tolerances. Components with defects are deduced from the combination of two model sets which are obtained by using two sub-algorithms. A first sub-algorithm incorporates dimensional tolerances in CAD model. This model founds relationships between component dimensions (driving and driven dimensions) and performs a three dimension tolerancing chain by a technique based on connected graphs. The second sub-algorithm tacks into account geometrical tolerances in CAD model. Tolerance zone is discretized by parameters deduced from deviation torsor of toleranced element. This discretization allows obtaining possible realistic configuration of the toleranced element. Then, face movements are realized to obtain components with defects. Thus, assemblies with defects can be obtained by performing various combinations between components with defects. Nevertheless, the assembly regeneration, with realistic components, requires redefining assembly mates which are initially assigned to nominal assembly. Then, a new approach to defining realistic assembly mates in the case of rigid assembly is presented.

Improving the numerical model requires consideration of tolerances in the CAD model. Previous research works have contributed to obtaining components on the configurations with defects from the dimensional and geometric tolerances. Nevertheless, in bottom-up design process, the assembly regeneration, with these components with defects, requires redefining assembly mates which are initially assigned to nominal assembly. Thus, this paper presents a new approach to defining realistic assembly mates in the case of rigid assembly fully constrained with joints without clearance. This method is validated though components with planar and cylindrical face.

Colloque avec actes et comité de lecture. Internationale.; International audience; The activity of design and mechanical analyses are in close connection. The increasing tendency to integrate these two activities, while guaranteeing the reduction of the simulation time, obliges us to carry out the analyses stage on adapted models to the objective of analyses. The latter are the results of the simplifications operations carried out on the original model. In this paper, we propose a tool for simplification of B-rep model mark, which makes it possible to generate the two models of predetermination and checking, while being based on a whole of identifying information of details that can be idealized. The developed tool is based on a hybrid method which uses two techniques: Removal of details and fusion of faces. In order to validate our tool, we have studied a set of mechanical parts, which shows the significant profit in computing times, all of them respect the precision wished for the results of simulation.

International audience; Book Front Matter of AICT 388

Colloque avec actes et comité de lecture. Internationale.; International audience; La simplification de la géométrie CAO est une étape de préparation du modèle CAO, qui se place en amont de la phase de simulation de comportement d'une pièce ou d'un système mécanique. Entre autres le concepteur est appelé à effectuer plusieurs calculs pour valider les solutions proposées, l'objectif de cet papier c'est de présenter une méthode, multi-objectifs et multi-critères basée sur un algorithme original pour la génération des modèles des calculs par idéalisation de modèle CAO. Une validation de la méthode sur des exemples des pièces mécaniques est également présentée.

Colloque avec actes et comité de lecture. Internationale.; International audience; This paper presents a method based on an original algorithm in order to prepare the design geometric model to a simulation by the finite element method. It consists on the idealization of the CAD geometry by eliminating details(holes, chamfers, etc.).These details increase the computing time due to a refined mesh in these details, which are considered as constraints hubs, without providing more precision in the simulation.

Nowadays, the integration of the different steps of mechanical design process (Design, analysis and manufacturing) is a necessity to reduce the time of design and optimization. This tendency of integrating CAD/CAM/Analysis and automation of the corresponding processes requires shared data between the various tasks using an integrated product model. Our research is oriented to CAD/CAM/Analysis integration by rebuilding the CAD model (BREP) starting from the FE results (deformed mesh).; De nos jours, l'intégration entre les différentes étapes de modélisation d'un produit mécanique est une nécessité afin de réduire le temps de conception et d'optimisation, de valider rapidement de nouveaux concepts et ainsi de gagner en coût, en délai et en qualité. Cela se traduit par une meilleure communication entre les différents outils de CAO et d'analyse. Cette tendance nécessite l'intégration des données entre les différentes tâches et l'unicité du modèle numérique. Cette intégration doit avoir le sens large du terme, c'est-à-dire de la conception vers le calcul et inversement. Notre activité de recherche tente à améliorer cette intégration à travers le développement d'un outil de reconstruction du modèle CAO à partir des résultats de simulation (maillage déformé).

Nowadays, the integration of the different steps of mechanical design process (Design, analysis and manufacturing) is a necessity to reduce the time of design and optimization. This tendency of integrating CAD/CAM/Analysis and automation of the corresponding processes requires shared data between the various tasks using an integrated product model. Our research is oriented to CAD/CAM/Analysis integration by rebuilding the CAD model (BREP) starting from the FE results (deformed mesh).; De nos jours, l'intégration entre les différentes étapes de modélisation d'un produit mécanique est une nécessité afin de réduire le temps de conception et d'optimisation, de valider rapidement de nouveaux concepts et ainsi de gagner en coût, en délai et en qualité. Cela se traduit par une meilleure communication entre les différents outils de CAO et d'analyse. Cette tendance nécessite l'intégration des données entre les différentes tâches et l'unicité du modèle numérique. Cette intégration doit avoir le sens large du terme, c'est-à-dire de la conception vers le calcul et inversement. Notre activité de recherche tente à améliorer cette intégration à travers le développement d'un outil de reconstruction du modèle CAO à partir des résultats de simulation (maillage déformé).