Détermination de la répartition spatiale optimale des sources thermiques dans un plateau chauffant

International audienceDans ce travail, on s'intéresse à l'optimisation du chauffage d'un outillage (plateau chauffant) utilisé dans la mise en forme de matériaux composites à hautes températures (~400°C). L'objectif recherché est d'assurer la maîtrise du champ de température en tout point à la surface de l'outillage qui doit reproduire un champ consigne donné afin de chauffer un moule ayant une forme complexe. Pour ce faire, une procédure a été mise en place afin de déterminer la répartition spatiale optimale des sources thermiques de chauffage. La démarche proposée comporte deux étapes : (i) la définition d'une courbe paramétrée qui définit la répartition spatiale des sources de chauffage dans l'épaisseur du plateau chauffant et (ii) l'utilisation d'une méthode inverse couplant un algorithme d'optimisation stochastique avec un code de calcul par éléments finis. Cette deuxième étape permet d'ajuster cette courbe afin d'obtenir un champ de température simulé le plus proche possible de celui voulu à la surface du plateau. On étudie l'évolution de cet écart entre les champs de température ainsi que la consommation énergétique en fonction du nombre de sources retenu. Nomenclature (11 points, 2 colonnes) H Hauteur (m) Valeur maximale de (°C) L Largeur (m) Température normalisée entre [0,1] et Paramètres de la courbe à optimiser Courbe paramétrée Température consigne (°C) Ecart quadratique moyen (°C) Valeur minimale de (°C

Optimisation et contrôle thermique des outillages dans la mise en oeuvre des polymères

L'optimisation énergétique des procédés de fabrication demeure un axe de recherche d'actualité. Dans ce travail, nous proposons deux pistes d'amélioration concernant le procédé de la mise en oeuvre des matières plastiques. L’objectif recherché étant d’assurer la maîtrise du champ de température en tout point à la surface de l’outillage qui doit reproduire un champ consigne donné afin de chauffer un moule ayant une forme complexe. Pour ce faire, nous avons mis en place une stratégie de dimensionnement des sources thermiques des outillages (plateaux chauffants) utilisés dans l’industrie de la transformation des polymères (caoutchouc, plastiques et composites). La démarche retenue s'appuie sur l'hypothèse d'un transfert thermique 1D entre les plateaux chauffants et le moule. Les résultats numériques obtenus illustrent clairement l'intérêt que présente la technique proposée qui réduit le nombre de paramètres à optimiser tout en profitant de la puissance des calculs de type éléments finis. Les résultats montrent que la technique proposée est efficace. De plus, il a été montré que cette technique peut être utilisée pour réduire la consommation d'énergie. La seconde partie de ce travail, quant à elle, concerne l'implémentation d'un algorithme de commande afin de suivre au mieux une consigne de température donnée. Dans cette problématique, nous avons considéré successivement le plateau chauffant qui contient les éléments chauffants, puis le moule vide placé sur le plateau avant de compléter l'étude avec la prise en compte du cas d'un moule dont les empreintes sont remplies de polymère. Basé sur un modèle fin des transferts thermiques dans le système étudié, à la fois multi–entrées multi-sorties, un contrôleur MPC a été développé pour asservir, en temps réel et en boucle fermée, le système considéré. L'asservissement a été d'abord validé sur un banc numérique puis sur le banc expérimental avec des champs de température consigne dynamique et un contrôle au plus près des empreintes.Energy optimization of manufacturing processes remains an up-to-day research topic. In this work, we propose two strategies of improvement concerning the process of plastic materials thermoforming. The aim underling this study is to ensure an effective control of the temperature field at any point on the surface of the heating tooling in order to deliver the needed energy amount by the mold. In order to do this, we have first implemented a strategy for designing the heating sources of tooling (heating plates) used in the polymer processing industry (rubber, plastics and composites). The approach adopted relies on the hypothesis of a 1D heat transfer between the heating plates and the mold. The numerical results obtained illustrate the advantage of the proposed technique which reduces the number of parameters to be optimized while taking advantage of the power of finite element calculations. The results show that the proposed technique is effective and can be furthermore used to reduce energy consumption. The second part of this work concerns the implementation of a control algorithm in order to follow at best a given temperature setpoint. In this problem, we considered successively the heating plate which contains the heating elements. After that, the study was extended to take into account the presence of an empty mold placed on the plate before completing the investigation by considering the case of a mold whose cavity is filled with a polymer. Based on a fine model of heat transfer in the studied system (heating plates, mold and polymer) and considering both multi-input multi-output, an MPC controller was developed for monitoring, in real time and in closed loop, the system under consideration. The control was validated on both digital and experimental setups with dynamic temperature setpoint fields

Model Predictive Control Applied to Thermal Regulation of Thermoforming Process Based on the ARMAX Linear Model and a Quadratic Criterion Formulation

International audienceModel Predictive Control Applied to Thermal Regulation of Thermoforming Process Based on the ARMAX Linear Model and a Quadratic Criterion Formulation. Abstract: Energy consumption efficiency is a major concern for the material processing industry such as thermoforming process and molding. Indeed, these systems should deliver the right amount of energy at the right time to the processed material. Recent technical development as well as the particularities of the heating system dynamics made the Model Predictive Control (MPC) one of the best candidate for thermal control of several production process like molding and composite thermoforming to name a few. The main principle of this technique is to use a dynamic model of the process inside the controller in real time in order to anticipate the future behavior of the process which allows the current timeslot to be optimized, while tacking future timeslots into account. This study presents a procedure based on a predictive control that brings balance between optimality, simplicity and flexibility of its implementation. The development of this approach is progressive starting from the case of a single zone before its extension to the multizone and / or multisource case, taking thus into account the thermal couplings between the adjacent zones. After a quadratic formulation of the MPC criterion to ensure the thermal control, the linear expression is retained in order to distribute the calculation load thanks to the use of the ARMAX linear decomposition methods. The effectiveness of this approach is illustrated by experiment and simulation

Implementation of a parametric procedure allowing efficient positioning of heat sources: application to high-temperature composites thermoforming process

This work describes the implementation of a simple procedure that helps to easily position the heating elements in press plates used in high-temperature composites thermoforming process. The developed method permits to obtain desired temperature profiles on the surface of the press plates through two main steps. The first step consists in finding out an appropriate parametric curve that defines the spatial location of the heating sources into the thickness of the press heating plates. The second step uses an inverse method that combines a stochastic optimization algorithm in conjunction with finite element simulations. This second step serves for the adjustment of the position curve parameters to obtain a simulated temperature profile as close as possible to the expected one at the press plates surface. This easy-to-implement approach is shown to be very effective to rapidly obtain a suitable location of the heat sources that minimizes energy consumption

Implementation of a parametric procedure allowing efficient positioning of heat sources: application to high-temperature composites thermoforming process

International audienceThis work describes the implementation of a simple procedure that helps to easily position the heating elements in press plates used in high-temperature composites thermoforming process. The developed method permits to obtain desired temperature profiles on the surface of the press plates through two main steps. The first step consists in finding out an appropriate parametric curve that defines the spatial location of the heating sources into the thickness of the press heating plates. The second step uses an inverse method that combines a stochastic optimization algorithm in conjunction with finite element simulations. This second step serves for the adjustment of the position curve parameters to obtain a simulated temperature profile as close as possible to the expected one at the press plates surface. This easy-to-implement approach is shown to be very effective to rapidly obtain a suitable location of the heat sources that minimizes energy consumption

Implementation of a parametric procedure allowing efficient positioning of heat sources: application to high-temperature composites thermoforming process

This work describes the implementation of a simple procedure that helps to easily position the heating elements in press plates used in high-temperature composites thermoforming process. The developed method permits to obtain desired temperature profiles on the surface of the press plates through two main steps. The first step consists in finding out an appropriate parametric curve that defines the spatial location of the heating sources into the thickness of the press heating plates. The second step uses an inverse method that combines a stochastic optimization algorithm in conjunction with finite element simulations. This second step serves for the adjustment of the position curve parameters to obtain a simulated temperature profile as close as possible to the expected one at the press plates surface. This easy-to-implement approach is shown to be very effective to rapidly obtain a suitable location of the heat sources that minimizes energy consumption