A local/global non-intrusive coupling approach for localized crack growth simulation

International audienceThe question of the inclusion of a crack and its propagation in a finite element (FE) model initially not intended for this, is a question which is still today the subject of numerous studies. A special effort is dedicated to the development of tools increasingly generic, flexible and simple to implement and to use. In this sense, X-FEM has achieved a first step towards clearly less intrusive simulation of fracture problems. To reduce further this intrusiveness, a new family of non-intrusive coupling algorithms has recently been intiated by [1]. Theses methods are dedicated to global FE model solved by a blackbox software in which a local phenomena (plasticity (1] or localized loading [2]) appears, that the global model is not able to account for. The idea is to develop a local/global coupling algorithm while avoiding any modification of the industrial code used to simulate the global problem. These coupling algorithms have been originally based on domain decomposition (DD) solvers [1,2]. Here an alternative algorithm based on a localised multigrid algorithm [3] is proposed for the simulation of mixed-mode crack propagation, while respecting the constraint of non-intrusiveness of the global problem [4]. For the global model, the contribution of the local patch consists in additional nodal efforts near the crack, which makes it compatible with most softwares. The shape of the local model is also adapted automatically during mixed mode propagatio

Monitoring structural scale composite specimens in a post‐buckling regime: The integrated finite element stereo digital image correlation approach with geometrically non‐linear regularization

International audienceBackground: Even though the simulations used to describe the failure of laminates are becoming more and more predictive, complex testing under multiaxial loadings is still required to validate the design of structural parts in a wide range of industrial domains. It is thus essential to assess the actual boundary conditions to allow for an objective comparison between testing and calculations, in particular since the structural tests are complex and often leads to buckling. Therefore, accurate estimation of force and moment fluxes applied to the specimen is critical. In this context, stereo DIC has proven to be an important measurement tool and provides very well resolved surface displacement fields, but the exploitation of such measurements to calculate fluxes remains problematic when testing composites. Objectives: The first objective of this study is both to reduce the uncertainty associated with fluxes determination on a complex test and to simplify the extraction process with respect to existing procedures. The second objective is to make this methodology robust to geometrically nonlinear deformations.Methods: In this paper, we propose a new methodology that extracts minimal boundary conditions in the form of 3D mechanically admissible displacements fields. The approach developed uses a Finite-Element Stereo Digital Image Correlation (FE-SDIC) method regularized by the means of mechanical behavior admissibility equations.Results: Results show that the new methodology outputs much more accurate fluxes than classical data generated from multiple differentiations of the displacement fields. Excellent noise robustness is obtained and quantified.Conclusions: Numerical predictions have been satisfactorily compared with experimental data from one structural scale composite specimen under complex testing

POD-based model order reduction for the simulation of strong nonlinear evolutions in structures: Application to damage propagation

In this paper, we develop a bridge between POD-based model order reduction techniques and the classical Newton-Krylov solvers to derive an efficient solution procedure for highly nonlinear problems undergoing strong topological changes

POD-based model order reduction for the simulation of strong nonlinear evolutions in structures: Application to damage propagation

International audienceIn this paper, we develop a bridge between POD-based model order reduction techniques and the classical Newton-Krylov solvers to derive an efficient solution procedure for highly nonlinear problems undergoing strong topological change

The VERTEX program: complex loading and validation of aeronautic composite structures

International audienceno abstrac