A note on topological properties of volumes constructed from surfaces

Converting surfaces into a volume has a long interest in several communities, e.g. the computational mechanics community. This process involves having specific surfaces which can be converted into a solid, i.e., a volume. This paper presents in a clear and brief manner the topological properties conserved during surface to volume transformation. We state the limits of this approach if a specific volume structure is required. Volume structures can be a coarse volume organization or meshes. For that purpose, surface manifolds are mathematically turned into a volume manifold. Topological tools are presented to understand which properties are transmitted to the volume and which ones are unset. Developments are submitted both for continuous and discrete manifolds using CW-complexes

Mixed-mode stress intensity factors for graded materials

AbstractIn this paper, we present a general method for the calculation of the various stress intensity factors in a material whose constitutive law is elastic, linear and varies continuously in space. The approach used to predict the stress intensity factors is an extension of the interaction integral method. For this type of material, we also develop a systematic method to derive the asymptotic displacement fields and use it to achieve better-quality results. A new analytical asymptotic field is given for two special cases of graded materials. Numerical examples focus on materials with space-dependent Young modulus

A mixed locking-free NURBS-based solid-shell element for nonlinear solid mechanics

International audienceno abstrac

A mixed locking-free NURBS-based solid-shell element for nonlinear solid mechanics

International audienceno abstrac

3D volumetric isotopological meshing for finite element and isogeometric based reduced order modeling

International audienc

Validation de critères de bifurcation pour la prédiction du flambage par fluage de structures coques épaisses

International audienceOn présente dans ces travaux une méthode de validation d'un critère de flambage par fluage sur des structures coques. Cette méthode utilise un couplage expérimental/numérique ; elle s'appuie pour la partie expérimentale sur la corrélation d'image 2D et 3D et l'approche FEMU. Pour la partie numé-rique le critère de bifurcation à valider s'appuie sur le critère d'instabilité de Hill, modifié pour l'appli-cation aux matériaux dont le comportement est viscoplastique. Les capacités de prédiction de ce critère seront évaluées grâce à des essais en compression et en pression externe sur structures physiques en alliage SAC305, alliage à bas point de fusion obtenu par fonderie

The Embedded Isogeometric Kirchhoff-Love Shell: from Design to Shape Optimization of non-conforming stiffened multipatch Structures

International audienceIsogeometric shape optimization uses a unique model for the geometric description and for the analysis. The benefits are multiple: in particular, it avoids tedious procedures related to mesh updates. However, although the analysis of complex multipatch structures now becomes tractable with advanced numerical tools, isogeometric shape optimization has not yet been proven to be applicable for designing such structures. Based on the initial concept of integrating design and analysis, we develop a new approach that deals with the shape optimization of non-conforming multipatch structures. The model is built by employing the Free-Form Deformation principle. Introducing NURBS composition drastically simplifies the imposition of the shape updates in case of a non-conforming multipatch configuration. In the case of stiffened structures, the use of embedded surfaces enables to tackle the geometric constraint of connecting interfaces between the panel and the stiffeners during shape modifications. For the analysis, we introduce the embedded Kirchhoff-Love shell formulation. The NURBS composition defines the geometry of the shell while the displacement field is approximated using the same spline functions as for the embedded surface. We also formulate a new mortar method to couple non-conforming Kirchhoff-Love shells which intersect with any angle. We apply the developed method on different examples to demonstrate its efficiency and its potential to optimize complex industrial structures in a smooth manner