Mathématiques industrielles
An updated Lagrangian method with error estimation and adaptive remeshing for very large deformation elasticity problems
Léger, Sophie, André Fortin, Cristian Tibirna and Michel Fortin
GIREF, Département de mathématiques et de statistique, Université Laval

Accurate simulations of large deformation hyperelastic materials by the finite element method is still a challenging problem. In a total Lagrangian formulation, even when using a very fine initial mesh, the simulation can break down due to severe mesh distortion.  Error estimation and adaptive remeshing on the initial geometry are helpful and can provide more accurate solutions (with a smaller number of degrees of freedom) but are not sufficient to attain very large deformations. The updated Lagrangian formulation where the geometry is periodically updated is then preferred. Remeshing may still be necessary to control the quality of the elements and to avoid too severe mesh distortion.  It then requires frequent data transfer from the old mesh to the new one and this is a very delicate issue. If these transfers are not done appropriately, accuracy can be severely affected. In this paper, we present an updated Lagrangian formulation where the error on the finite element solution is estimated and adaptive remeshing is performed in order  to concentrate the elements of the  mesh where the error is large, to coarsen the mesh where the error is small and at the same time to control mesh distortion. In this way, we can reach high level of deformations while preserving the accuracy of the solution. Special attention is given to data transfer methods and a very accurate cubic Lagrange projection method is introduced. A very efficient continuation method is used to automatically pilot the complete algorithm including load increase, error estimation, adaptive remeshing and data transfer. A number of examples will be presented and analyzed.

Jeudi, 20 juin, 12h00
Salle George V