Finite element modeling and simulation of roll bending process for forming a thick conical hollow shape

Zeng, Jun (2007). Finite element modeling and simulation of roll bending process for forming a thick conical hollow shape. Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

Prévisualisation

PDF Télécharger (3MB) | Prévisualisation

Résumé

The objective of the project presented in this thesis is to model and simulate the dynamic roll-bending process for forming a thick plate to a conical hollow shape. The project is realized using the Finite Element Method (FEM), which is integrated into the ANSYS/LS-DYNA software. In this study, the continuous three-roll pyramidal configuration is applied to form a thick plate to a conical hollow shape. The final goal is to provide a simulation tool that allows the optimization of the parameters of the process, and to demonstrate the feasibility of fulfilling the conical geometry adapted to the manufacture of Francis turbine crowns.

The kinematic and geometrie relationships of the process are developed first: they allow sliding to be kept to a minimum between the workpiece and the rolls using conical rolls. Detailed steps for modeling the Finite Elements (FM), including the element type, the meshing, the contact surfaces, the boundary conditions and the constraints, are then presented. This 3D simulation is based on the explicit finite element method, which is able to deal with nonlinear elasto-plastic deformation behavior. Next, a typical example is presented to demonstrate the feasibility of modeling the process using this numerical tool. The results of the dynamic roll-bending process, going from the initial plate plane to its final conical form are examined, that is, the progressive change in the geometry along with the evolution of the residual stress distribution in the workpiece. A convergence test, which varies the meshing size, is also carried out in order to ensure that the proper element sizes are chosen. Furthermore, the reaction forces and the residual stress obtained through the numerical simulation are compared with the results of a simplified analytic calculation. To compare the geometric precision of the shape generated with that of that specified, a dimensional verification algorithm was developed. The algorithm, which is based on the Levenberg-Marquardt nonlinear optimization method, allows the smoothing of the coordinates of the nodes of the final shape obtained, based on a conical surface. Next, the deviations are calculated in order to analyze the effects of the variables of the process and of the simulation parameters on the final forming results. These parameters include the friction coefficient, the plate thickness, the materials properties, the spatial arrangement of the outer rolls and the plate temperature. This sensitivity study evaluates the influence of the parameter on the reaction forces, the residual stresses and the geometric compliance of the final formed piece.

Titre traduit

Finite element modeling and simulation of roll bending process for forming a thick conical hollow shape

Résumé traduit

L'objectif du projet exposé dans ce mémoire est de modéliser et de simuler le procédé dynamique du roulage des tôles fortes pour former des troncs de cônes. Le projet est réalisé en utilisant la méthode des éléments finis (MÉF) intégrée dans le logiciel ANSYS/LS-DYNA. Dans cette étude, la configuration pyramidale de roulage continu par flexion avec trois rouleaux est utilisée pour former une pièce conique à partir de tôles planes épaisses. La finalité est de fournir un outil de simulation permettant l'optimisation des paramètres du procédé, et de montrer sa faisabilité pour réaliser des géométries coniques adaptées à la fabrication de couronnes de turbine Francis. Pour mesurer la précision géométrique de la forme générée par rapport à celle spécifiée, un algorithme de vérification dimensionnelle a été développé. Cet algorithme, basé sur la méthode d'optimisation non-linéaire de Levenberg-Marquardt, permet de faire un lissage, selon une surface conique, des coordonnées des noeuds de la forme finale obtenue.

Type de document:	Mémoire ou thèse (Mémoire de maîtrise électronique)
Renseignements supplémentaires:	"Master's thesis submitted to École de technologie supérieure in partial fulfillment of the requirements for the master's degree in mechanical engineering". Bibliogr. : f. [107]-108.
Mots-clés libres:	ANSYS/LS-DYNA, Cone, Creux, Dynamique, Element, Epais, Fini, Fort, Logiciel, Methode, Modele, Optimisation, Procede, Roulage, Rouleau, Simulation, Tole, Turbine
Directeur de mémoire/thèse:	Directeur de mémoire/thèse Liu, Zhaoheng
Codirecteur:	Codirecteur Champliaud, Henri
Programme:	Maîtrise en ingénierie > Génie mécanique
Date de dépôt:	14 avr. 2011 14:19
Dernière modification:	06 déc. 2016 22:50
URI:	https://espace.etsmtl.ca/id/eprint/608

Gestion Actions (Identification requise)

Dernière vérification avant le dépôt