Search results for "physics.class-ph"
showing 10 items of 334 documents
Novel Porous Carbon Material for the Detection of Traces of Volatile Organic Compounds in Indoor Air
2021
International audience; A highly sensitive and selective silicon-based microanalytical prototype was used to identify a few ppb of volatile organic compounds (VOCs) in indoor air. Herein, a new nonactivated tannin-derived carbon synthesized by an environmentally friendly method, DM2C, a MIL-101(Cr) MOF, and a DaY zeolite were selected for the preconcentration of BTEX compounds (i.e., benzene, toluene, ethylbenzene, and xylenes). Integrating a small amount of these nanoporous solids inside a miniaturized preconcentration unit led to excellent preconcentration performance. By taking advantage of the high adsorption−desorption capacities of the DM2C adsorbent, concentrations as low as 23.5, 30…
Digital Correlation Method Based on Micro-geometrical Texture Pattern for Strain Field Measurement
2011
International audience; Image correlation methods are widely used in experimental mechanics to obtain displacement field measurements. Currently, these methods are applied using digital images of the initial and deformed surfaces sprayed with black or white paint. Speckle patterns are then captured and the correlation is performed with a high degree of accuracy to an order of 0.01 pixels. In 3D, however, stereo-correlation leads to a lower degree of accuracy. Correlation techniques are based on the search for a sub-image (or pattern) displacement field. The work presented in this paper introduces a new correlation-based approach for 3D displacement field measurement that uses an additional …
Analytical and finite element analyses on reliability of carbon fibre reinforced plastics
2013
International audience
Modelling the effect of porosity on the mechanical properties of unidirectional composites. The case of thick-walled pressure vessels
2018
International audience; The present article highlights morphological features present in composite pressure vessels. The use of X-ray microtomography provides three-dimensional information about the voids in a large thick-walled type 3 pressure vessel at the mesoscopic scale. The observations show that the porosity structure depends strongly on composite thickness and orientation. A numerical approach is proposed to model realistically the damage phenomena in pressure vessels.
Durability of a 3D woven composite assisted by finite element multi-scale modelling
2012
International audience; The textile composite studied is a 3D woven composite. A unit cell is defined by using microscopic examinations of the microstructure. A multiscale approach assisted by the finite element method is performed in order to estimate the effective properties of the composite and then to access to local stress field. This approach allows the determination of the kind of load to which warp yarns are subjected. Moreover, detailed analysis of damaged model using different configurations of broken yarns are treated. The evolution of the stress concentration coefficient highlight the load transfers due to consecutive yarn breaks.
The numerical challenges in multiphysical modeling of laser welding with arbitrary Lagrangian-Eulerian method
2018
International audience; The interaction of high power laser beam with metallic materials produces a number of interconnected phenomena that represent a serious challenge for numerical modeling, especially for creation of auto-consistent models. Additional difficulty consists in lack of data on materials properties at the temperatures superior to their melting point. The present work summarizes the numerical challenges in creation and validation of free-surface models using ALE moving mesh coupled with heat transfer equation and Navier-Stokes fluid flow.
Predicting mechanical behaviour and damage kinetics of a 3D interlock composite materials by using a multiscale approach
2012
International audience; The present work aims to investigate the mechanical behaviour and the damage kinetics of a3D interlock woven fabric composite, especially used for natural gas tanks dedicated to thetransportation industry. On the one hand, we aim at predicting the macroscopic coefficients ofthe stiffness matrix by homogenization multiscale approach. For this, we identified a basicunit cell which represents well the composite microstructure. On the other hand, damagemechanisms are analyzed: optical microscopy examinations on damaged specimens revealedseveral types of defects. We used the same multi-scale approach to assess the impact of thesedefects on the decrease of stiffness.
Rhéologie et déformation du verre dans des conditions extrêmes
2018
Hardness measurements performed at room temperature have proven that glass can flow under elevated pressure. During industrial glass production processes, the actual distribution of stress components in the glass during scribing remains, to date, poorly quantified, and thus continues to be challenging to model numerically. To better quantify the viscous contribution to the rheology of glass, the effect of pressure on the viscosity and structural relaxation of glass, needs to be quantified experimentally by in situ deformation measurements.In this thesis, I performed experiments and models to study: (i) the volumetric relaxation of glass after high-pressure treatment above the glass transiti…
Dynamics of hydrofracturing and permeability evolution in layered reservoirs
2015
International audience; A coupled hydro-mechanical model is presented to model fluid driven fracturing in layered porous rocks. In the model the solid elastic continuum is described by a discrete element approach coupled with a fluid continuum grid that is used to solve Darcy based pressure diffusion. The model assumes poro-elasto-plastic effects and yields real time dynamic aspects of the fracturing and effective stress evolution under the influence of excess fluid pressure gradients. We show that the formation and propagation of hydrofractures are sensitive to mechanical and tectonic conditions of the system. In cases where elevated fluid pressure is the sole driving agent in a stable tec…
Residual a posteriori error estimation for frictional contact with Nitsche method
2023
We consider frictional contact problems in small strain elasticity discretized with finite elements and Nitsche method. Both bilateral and unilateral contact problems are taken into account, as well as both Tresca and Coulomb models for the friction. We derive residual a posteriori error estimates for each friction model, following [Chouly et al, IMA J. Numer. Anal. (38) 2018, pp. 921-954]. For the incomplete variant of Nitsche, we prove an upper bound for the dual norm of the residual, for Tresca and Coulomb friction, without any extra regularity and without a saturation assumption. Numerical experiments allow to assess the accuracy of the estimates and their interest for adaptive meshing …