28 research outputs found

    Evaluation of the effectiveness of the interval computation method to simulate the dynamic behavior of subdefinite system: application on an active suspension system

    Get PDF
    International audienceA new design approach based on methods by intervals adapted to the integration of the simulation step at the earliest stage of preliminary design for dynamic systems is proposed in this study. The main idea consists on using the interval computation method to make a simulation by intervals in order to minimize the number of simulations which allow obtaining a set of solutions instead of a single one. These intervals represent the domains of possible values for the design parameters of the subdefinite system. So the parameterized model of the system is solved by interval. This avoids launching n simulations with n values for each design parameter. The proposed method is evaluated by several tests on a scalable numerical example. It has been applied to solve parameterized differential equations of a Macpher-son suspension system and to study its dynamic behavior in its passive and active form. The dynamic model of the active suspension is nonlinear but linearisable. It is transformed into a parameterized state equation by intervals. The solution to this state equation is given in the form of a matrix exponential. Three digital implementations of exponential have been tested to obtain convergent results. Simulations results are presented and discussed

    Pre-designing of a mechatronic system using an analytical approach with dymola

    Get PDF
    This paper presents a pre-dimensioning method applied to a mechatronic system and regarding the vibrational aspect, through a simple modeling process in Dymola environment. We study the vibration transmission between dynamic exciters (motors) and receivers (electronic cards) which are located on a simply supported rectangular plate, using an analytical approach. This new method will allow us to perform representative and robust modeling and simulation. The solution for this issue would be a pre-sizing and pre-positioning procedure. It aims to determine a set of possible technical solutions and principal characteristics before the definitive choice of components and precise sizing of the system. The presented method predicts also behaviour of the mechatronic system. In order to validate the model with respect to the finite element method, selected simulation results are presented

    Contribution à la génération assistée par ordinateur du tolérancement de fabrication 3D

    No full text
    Lors de la réalisation des pièces d un mécanisme, le fabricant se doit de respecter les exigences géométriques exigées par le client. Ces exigences sont issues de besoins fonctionnels du mécanisme à tous les stades de son cycle de vie. Le fabricant lors des opérations successives d usinage, avec ou sans enlèvement de matière, doit définir les exigences de la géométrie ajoutée au poste. La combinaison de ces exigences affectées de leur tolérance doit être comparée aux exigences géométriques du client. L objectif du travail présenté est la définition d une méthode optimisant, rationnellement, les exigences géométriques des surfaces créées. Nous définirons les spécifications géométriques, au sens de l iso 1101, mais la valeur de ces tolérances ne sera pas abordée dans ce travail, d autres équipes ayant réalisés des travaux de qualité. L étude poussée de la méthode 1D utilisée dans l ensemble du groupe Renault pour définir les fiches schéma nous a montré ses limites lors de la multiplication des posages orientés différemment. Par contre l optimisation du choix des spécifications influentes a retenu notre intérêt. L étude des méthodes du bureau d études pour la recherche de spécifications des pièces composant un mécanisme nous a permis de faire l analogie avec les phases d usinages. En effet le passage successif de la pièce sur les différents postes d usinage s apparente à des assemblages temporaires qui mettent en œuvre des surfaces actives qu elles soient de posage ou créées à l opération. La modélisation du processus d usinage à l aide d une représentation graphique est largement utilisée par la communauté travaillant dans le tolérancement. Nous avons développé dans notre travail un modèle de représentation appelé SPIDER GRAPH. Ce modèle essentiellement pédagogique nous permet de visualiser le déroulement de l algorithme développé à l occasion de ce mémoire. Il met en valeur la succession de liens entre les différentes surfaces intervenant pour réaliser une spécification exigée. Deux méthodes utilisant le concept SATT pour la mise en position des ensembles de surfaces de tolérancement de fabrication 3D sont décrites : Recherche des chemins du process contraignant les degrés de liberté de la spécification fonctionnelle . Nous avons identifié, en se référant aux résultats développés par DESROCHERS, toutes les combinaisons possibles entre des entités simples et leurs correspondances en termes de type de tolérance. Une validation par un exemple a été établie et un ensemble de spécifications géométriques de fabrication a été généré. Cette méthode qui s appui successivement sur les surfaces du système de référence ne permet pas une écriture se référant à des systèmes de référence. Nous avons donc développé une alternative à ce travail initial. Méthode rationnelle de tolérancement de fabrication 3D Cette méthode est représentée par un logigramme qui prend en compte la hiérarchie des surfaces lors des posages. Il prend également en compte les inversions de spécifications entre la référence et la surface spécifiée. Lors de la création de surfaces temporaires qu elles soient de posage ou d usinage, la méthode permet de spécifier ces surfaces dans les opérations considérées. Lors du développement de cette méthode originale, nous avons repris la totalité des fiches de cotations SATT, développées par CLEMENT et aussi les modélisations vectorielles de ces cas d association décrites par GAUNET. A l aide des lois d identification des paramètres de mise en position relative entre SATT, nous avons pu générer, l ensemble des spécifications géométriques capables de mener au respect de la spécification géométrique fonctionnelle. Cette méthode assure la traçabilité des liens successifs entre les surfaces actives lors des différentes opérations. Ces liens que l on peut représenter sur le SPIDER GRAPH permettront de déterminer algébriquement ou de façon probabiliste la conséquence de ces différents transferts de pièces entre les poste d usinage.During the realization of the mechanism pieces, the manufacturer must respect the customer geometrical requirements. These requirements arise from functional needs of the mechanism in all its life cycle stages. During the successive operations of manufacturing, with or without material removing, the manufacturer has to define the added geometry requirements in each phase. The combination of these requirements affected by their tolerance must be compared with the functional geometrical requirements. The objective the actual work is to define a method optimizing, in a rational way, the geometrical requirements of the created surfaces. We shall define the geometrical specifications, according to the standard ISO on 1101 , but the quantification of the tolerance zones will not be approached on this work, other teams have given good results. The 1D method, used in the whole of the group Renault to define process cards, is limited during the reproduction of positioning surfaces directed differently. On the other hand the optimization of the influential specifications retained our interest. The study of the engineering consulting firm method, used for the search of the each pieces specification composing a mechanism, allowed us to make analogy with the manufacturing phases. Indeed the successive manufacturing operation on various posts is similar to temporary assemblies which implement active surfaces whether they are positioning or machined surfaces, existing in this phase. The modeling of the manufacturing process by means of a graphic representation is widely used on the tolerance filed. We developed in our work a model of representation called SPIDER GRAPH. This essentially educational model allows us to show the progress of the algorithm, developed in this these. It emphasizes the succession of links between the various surfaces with intervene in the generation of needed manufacturing specification. Two methods based on the TTRS concept to select all needed surfaces in 3D manufacturing tolerancing are described: Search of the process links constraining the functional forbidden displacement . In this method we identified, by referring to the results developed by DESROCHERS, all the possible combinations between simple entities and their tolerance type correspondences. An example of validation is afterward established and a set of geometrical manufacturing specifications were generated. With this previous method we are constrained to treat the surfaces that constitute the functional reference system independently, one by one, which is not conform to the standard. What urged us to look for another alternative able to remedy to this problem. Rational method for 3D manufacturing tolerancing synthesis based on TTRS approach This method is represented by an algorithm which takes into account the hierarchy of positioning surfaces and the specifications inversions between the reference and the specified surface. During the creation of temporary surfaces, whether they are used for positioning or they are machined, the method allows to generate the appropriate tolerance specification in the considered phase. During the development of this method, we took back the totality of the tolerancing process TTRS cards, developed by CLÉMENT and also the vectorial modelling of these associations cases, described by GAUNET. With the relatives positioning parameters rules, we were able to generate at the end of the treatment all the geometrical specifications capable to ensure the respect of the functional geometrical specification. This method insures the traceability of the successive links between the active surfaces during the various manufacturing operations. These links which can be represented on the SPIDER GRAPH will allow determining mathematically or in a probability way the consequence of these various pieces transfer between machines.CHATENAY MALABRY-Ecole centrale (920192301) / SudocSudocFranceF

    5th international conference on design and modeling of mechanical systems

    No full text
    The 5th International Congress on Design and Modeling of Mechanical Systems (CMSM) was held in Djerba, Tunisia on March 25-27, 2013 and followed four previous successful editions, which brought together international experts in the fields of design and modeling of mechanical systems, thus contributing to the exchange of information and skills and leading to a considerable progress in research among the participating teams. The fifth edition of the congress (CMSM´2013), organized by the Unit of Mechanics, Modeling and Manufacturing (U2MP) of the National School of Engineers of Sfax, Tunisia, the Mechanical Engineering Laboratory (MBL) of the National School of Engineers of Monastir, Tunisia and the Mechanics Laboratory of Sousse (LMS) of the National School of Engineers of Sousse, Tunisia, saw a significant increase of the international participation. This edition brought together nearly 300 attendees who exposed their work on the following topics: mechatronics and robotics, dynamics of mechanical systems, fluid structure interaction and vibroacoustics, modeling and analysis of materials and structures, design and manufacturing of mechanical systems. This book is the proceedings of CMSM´2013 and contains a careful selection of high quality contributions which were exposed during various sessions of the congress. The original articles presented here provides an overview of recent research advancements accomplished in the field mechanical engineering

    Mathematical methodology for optimization of the clamping forces accounting for workpiece vibratory behaviour

    No full text
    This paper addresses the problem of determining the minimum clamping forces that ensure the dynamic fixturing stability. The clamping force optimization problem is formulated as a bi-level nonlinear programming problem and solved using a computational intelligence technique called particle swarm optimization (PSO). Indeed, we present an innovative simulation methodology that is able to study the effects of fixture-workpiece system dynamics and the continuously change due to material removal on fixturing stability and the minimum required clamping forces during machining. The dynamic behaviour of the fixtured workpiece subjected to time-and space-varying machining loads is simulated using a forced vibration model based on the regenerative vibrations of the cutter and workpiece excited by the dynamic cutting forces. Indeed, Material removal significantly affects the fixture-workpiece system dynamics and subsequently the minimum clamping forces required for achieving fixturing dynamic stability
    corecore