De l'impression 3d en céramique
Mesurer la déformation du sel, pour l'aménagement de réservoirs en cavités salines
Electromagnetic forming process for metallic pieces
Amélioration de la performance des éoliennes
Vers un stockage géologique du C02 avec impuretés
The test platform is a servo-hydraulic machine with the following nominal features:
Exploitation of such a high speed testing facility to measure the actual high strain rate behaviour of a material is often coupled to numerical simulations in order to dissociate the global response into that due the intrinsic material response and that due to inertial effects. For brittle materials, for example, numerical simulation makes it possible to identify the instant at which the homogeneous deformation of the specimen gauge lengths can be verified.
An inverse approach coupled to optimisation tools developed under the ZéBuLoN finite element code can then provide a robust identification of the material parameters of the proposed material laws.
The development of a mechanical test platform at high strain rates at the Centre des Matériaux responds to a growth in the demand for high-speed tests on the part of our industrial partners such as those in the automobile industry and its subcontractors (Renault, PSA, Plastic Omnium, etc.), the aeronautical industry (EADS, Airbus), and the energy and transport sectors (EDF, Europipe, Total, Institut Français du Pétrole, Atofina, Coflexip, etc.). The clear aim is firstly to reduce the time required for the development phase of a new product and secondly, to enable a more accurate prediction of reliability and durability. These objectives are obtained on the basis of the development of predictive simulation tools whereby materials can be chosen for the various components according to applied mechanical loading conditions.
The development of such simulation tools involves an indispensable phase which is the experimental description and modelling of the behaviour of a wide range of materials. Many applications require knowledge of the materials behaviour for a range of strain rates varying from 0.01 to several hundred s-1. An example of this are the conditions prevailing in crash-tests performed by the automobile industry. The non-linearity of the relationship between a material stress-strain response and strain rate (illustrated in the figures herewith) does not permit a sound extrapolation of the quasi-static response of materials and requires experimental determination. It is in response to this strong industrial need that a specific experimental procedure has been developed at the Centre des Matériaux to underpin the development of elastoviscoplastic constitutive laws for structural materials.
By virtue of its expertise and the diversity of its research themes, the Centre des Matériaux can boast of substantial experience in the modelling of the behaviour of metallic materials, composites, elastomers, polymers and metallic foams. At present, constitutive modelling of metallic materials and composites at high strain rates accounts for a substantial part of the research work conducted using this equipment.