Christelle Combescure

University of Southern Brittany | UBS · IRDL – Institut de Recherche Dupuy de Lôme

We present a general approach to the bifurcation analysis of elastic frameworks with symmetry. While group-theoretic methods for bifurcation problems with symmetry are well known, their actual implementation in the context of elastic frameworks is not straightforward. We consider frames comprising assemblages of Cosserat rods, and the main difficul...

In the context of architected materials, it has been observed that both long-wavelength instabilities leading possibly to localization and short-wavelength instabilities leading to the apparition of a deformation pattern could occur. This work proposes for the first time a comparison of the ability of two families of higher order equivalent media,...

This article presents a generic method to determine analytically the equivalent homoge- neous linear elastic behavior of any 2D architectured material and to determine its macro- scopic linear elasticity domain. The method is applied throughout the paper in the equilateral triangular case, as an example. Additional examples of square, isosceles rig...

Biological structures combine passive shape‐changing with force generation through intricate composite architectures. Natural fibers, with their tubular‐like structures and responsive components, have inspired the design of pneumatic tubular soft composite actuators. However, no development of passive structural actuation is available despite the r...

Architectured materials are often used for their high strength-to-weight ratio. For this matter, they are designed with high porosity which makes them sensitive to buckling under compressive loading. This buckling is usually predicted by numerical computations but very few experiments are available to confront these numerical results. Experimentall...

Architectured materials exhibit unconventional properties directly linked to their geometry. When composed of slender elements, architectured materials can undergo large deformations exhibiting geometric non-linearities through buckling or snapping behaviours of the cell walls. This can create a new pattern in the material with different properties...

We present a general approach to the bifurcation analysis of spatial framework struc- tures with symmetry. While group-theoretic methods for bifurcation problems with symmetry are well known, their actual implementation in the context of geometrically exact frameworks is not straightforward. We consider spatial structures comprising assemblages of...

A phase field model for anisotropic, elastoplastic fracture model in layered structures obtained by 3D printing processes is proposed. An extension of anisotropic phase field to elastoplasticity model is developed. The model is able to describe a transition from quasi-brittle to elastoplastic fracture behaviors depending on the angle of layers in t...

In this work we investigate the properties of elastic waves propagating in gyroid lattices. First, we rigorously characterize the lattice from the point of view of crystallography. Second, we use Bloch–Floquet analysis to compute the dispersion relations for elastic waves. The results for very long wavelengths are then compared to those given by cl...

In this work we investigate the properties of elastic waves propagating in gyroid lattices. First, we rigorously characterize the lattice from the point of view of crystallography. Second, we use Bloch-Floquet analysis to compute the dispersion relations for elastic waves. The results for very long wavelengths are then compared to those given by cl...

The mechanics of cellular honeycombs—part of the rapidly growing field of architected materials—in addition to its importance for engineering applications has a great theoretical interest due to the complex bifurcation mechanisms leading to failure in these nonlinear structures of high initial symmetry. Of particular interest to this work are the d...

An extension of the phase field method to model interfacial damage in elastoplastic composites is proposed. In the matrix, an elastoplastic phase field is employed to model the fracture process. To introduce interfacial damage between inclusions and the matrix, a strain density function depending on the jump due to decohesion is added to the total...

The present paper proposes a new efficient and robust algorithm for evaluating the loss of ellipticity criterion. While commonly used in 2D models for thin metal sheet forming processes, it is rarely evaluated in 3D structures due to the computational cost. The proposed algorithm is based on a Newton‐Raphson scheme and a multi‐sampling optimization...

The assumption of separated scales in homogenization implies that the characteristic wavelength of applied loads is large as compared to the dimensions of the het-erogeneities in the composite. If this assumption does not hold, classical homogenization methods fail to describe accurately the local fields. This is typically the case in some aerospac...

This paper explores the importance of nonlinear material properties in the design of hierarchical honeycomb materials. The recent literature on the design and optimization of linear material properties for hierarchical honeycombs is reviewed. Then a full nonlinear post-bifurcation numerical analysis is performed for five representative hierarchical...

The buckling and crushing mechanics of cellular honeycomb materials is an important engineering problem. Motivated by the pioneering experimental and numerical studies of Papka and Kyriakides (1994, 1999a,b), we review the literature on finitely strained honeycombs subjected to in-plane loading and identify two open questions: (i) How does the mech...

A new stress resultant nonlinear dissipative constitutive model for reinforced concrete (RC) plates under cyclic solicitations is presented. This constitutive model, named DHRC for Dissipative Homogenised Reinforced Concrete, is expressed within the usual thin plate kinematics framework. It is built by a periodic homogenisation approach using the a...

Recent advances in materials processing have lead to the creation of new classes of materials: hybrid and architectured materials. These materials, defined by a controlled periodic microstructure, are created in a ’Material-by-Design’ approach where a desired material is created through optimization with respect to performance or multifunctional pr...

Les matériaux à microstructure régulière tels que les matériaux architecturés présentent un grand nombre de symétries géométriques internes et leur comportement à la ruine peut ainsi devenir com-pliqué à étudier du fait d'instabilités multiples pouvant subvenir simultanément. Les techniques usuelles d'étude de la bifurcation comprennent alors un ri...

he post-bifurcation behavior of infinite hierarchal honeycomb structures is investigated using equivariant bifurcation theory and the group representation theory of space groups. A custom computational branch-following and bifurcation (BFB) code coupled with a finite element code (FEAP) is used to numerically explore a number of examples. First, a...

A new stress resultant constitutive model for reinforced concrete plates under cyclic solicitations is presented. This model is built by the periodic homogenisation approach using the averaging method and couples damage of concrete and periodic debonding between concrete and steel rebar. In one-dimensional situations, we derive a closed-form soluti...

Safety reassessments are periodically performed on the EDF nuclear power plants and the recent seismic reassessments leaded to the necessity of taking into account the non-linear behaviour of materials when modeling and simulating industrial structures of these power plants under seismic solicitations. A large proportion of these infrastructures is...

11e Colloque National en Calcul des Structures 13-17 Mai 2013 1 Modèle DHRC de comportement non linéaire de plaques en béton armé sous sollicitations sismiques. Résumé — Un nouveau modèle de comportement, appelé « Dissipative Homogenized Reinforced Concrete (DHRC) model », pour les plaques en béton armé sous sollicitations sismiques est présenté. C...

Inauguration Institut SEISM– 19 Déc. 2012 « Modélisation performante et réaliste en dynamique non linéaire des structures en béton armé »

This paper presents the construction of a global model of reinforced concrete plates dedicated to structures (slabs, walls…) subjected to low and moderate seismic solicitations, formulated according to the Generalized Standard Materials theory [5]. Regarding the context imposed by the applications considered one can identify three main objectives:...

RÉSUMÉ. Pour modéliser la tenue sismique de bâtiments en béton armé, on propose un modèle de comportement macroscopique d’endommagement pour le béton armé formulé sur des éléments plaques, dans le cadre standard généralisé ; on évite de représenter les phases adoucissantes liées à la dégradation du béton, en profitant de la contribution des armatur...