CNRS Wood Materials Research Laboratory

Nancy, France

CNRS Wood Materials Research Laboratory

Nancy, France
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Khelifa M.,CNRS Wood Materials Research Laboratory
WCTE 2016 - World Conference on Timber Engineering | Year: 2016

The behaviour of timber-steel hybrid beams for buildings is very complex because of the combination of the two very different materials that are wood and steel. Numerical simulation of such behaviour requires an accurate description of orthotropic material's behaviour with damage. This paper describes 3D-Finite Element (FE) simulation results obtained using an elasto-plastic model coupled with an isotropic ductile damage, and implemented into ABAQUS/Explicit FE software. After a short presentation of the constitutive equations and their related numerical aspects, the validation of the model was carried out by simulating timber-steel hybrid beams. Good agreement was found between FE and experimental results, showing the good capability of the model to predict the ductile damage evolution in bending test of timber-steel hybrid structures.


Szczurek A.,CNRS Jean Lamour Institute | Fierro V.,CNRS Jean Lamour Institute | Pizzi A.,CNRS Jean Lamour Institute | Pizzi A.,CNRS Wood Materials Research Laboratory | And 2 more authors.
Carbon | Year: 2014

Tannin-based, carbonised, polymerised High Internal Phase Emulsions (polyHIPEs) are described in detail for the first time. Such highly porous materials were prepared by emulsion-templating, using an aqueous phase made of tannin and a low amount of hexamine dissolved in water, sunflower oil, and ethoxylated castor oil. After hardening of the tannin-based resin, the oil was leached out and the resultant monoliths were pyrolysed. The porous structure of carbon polyHIPEs prepared with an initial oil fraction ranging from 43 to 80 vol.% has been investigated, as well as their mechanical and thermal properties. We show that the most homogeneous materials, having the smallest pores, the narrowest pore size distributions and also the highest mechanical properties, are those made with an initial oil fraction around 70 vol.%. Such value is close to random and hexagonal close packing fractions: 64% and 74%, respectively. © 2014 Elsevier Ltd. All rights reserved.


Szczurek A.,CNRS Jean Lamour Institute | Fierro V.,CNRS Jean Lamour Institute | Pizzi A.,University of Lorraine | Pizzi A.,CNRS Wood Materials Research Laboratory | And 2 more authors.
Carbon | Year: 2013

Aqueous solutions containing tannin, crosslinker and surfactant were used for transferring techniques used to produce foods such as mayonnaise, whipped cream and meringue, to the preparation of new kinds of cellular carbons. Emulsion-templating, i.e. leaching a hardened "mayonnaise" for removing the oil followed by pyrolysis led to carbon polyHIPEs (polymerised High Internal Phase Emulsions). The second kind of materials, obtained by whipping the emulsions, presented hierarchical porous structures made of cells whose walls had a polyHIPE texture. The third kind, obtained by whipping until stiff oil-free tannin solutions, was carbon "meringues" whose cell sizes were controlled by tannin concentration. © 2013 Elsevier Ltd. All rights reserved.


O'Loinsigh C.,University College Dublin | Oudjene M.,CNRS Wood Materials Research Laboratory | Shotton E.,University College Dublin | Pizzi A.,CNRS Wood Materials Research Laboratory | Fanning P.,University College Dublin
Composite Structures | Year: 2012

This paper presents experimental and numerical investigations on multi-layered timber beams using welded-through wood dowels in place of traditional poly(vinyl acetate) (PVAc)-adhesives (or metallic nails). Four-layer beams were constructed with varying numbers of dowels, in each, and then loaded using four-points bending tests to evaluate the mechanical performance of these beams. The practical difficulties encountered in constructing deeper multi-layer beams are discussed and possible solutions which have been employed for the purpose of this work, and proved successful are presented. In order to investigate thoroughly the full potential of multi-layered beams with a very limited number of experimental studies, a 3D FE model has been presented, validated against experimental results and then used to study some influential parameters. The results showed that a reasonable bending stiffness of multi-layered beams is achievable with a good combination of material and geometric parameters. © 2011 Elsevier Ltd.


Abdallah R.,University of Aleppo | Auchet S.,CNRS Wood Materials Research Laboratory | Meausoone P.J.,CNRS Wood Materials Research Laboratory
Biomass and Bioenergy | Year: 2014

Nowadays wood chips produced from raw material of inferior quality are mainly used to feed domestic and industrial boilers. For this use, a good chip size distribution and low manufacturing energy consumption are required. Cutting forces are still inaccurately measured during the wood chipping process, which implies the use of oversized chippers' motors. A test bench for chipping wood under reasonably realistic conditions of industrial production is improved by adding an indirect force measurement system with high bandwidth of 3KHz. The dynamic experimentations give the data needed to compute the curve presenting the vertical component of the cutting force, which is composed of three sections; the first one presents the values of the impact force; the second one is relatively straight and it refers to shear stress in wood; the third section corresponds to the period between two crosscuts. © 2014 Elsevier Ltd.


Oudjene M.,CNRS Wood Materials Research Laboratory | Meghlat E.-M.,Mouloud Mammeri University | Ait-Aider H.,Mouloud Mammeri University | Batoz J.-L.,Center Pierre Guillaumat 2
Composite Structures | Year: 2013

This paper discusses a numerical approach, based on beam-to-solid modelling, for the simulation of the nonlinear structural behaviour of timber-to-concrete composite beams made with screws. The present contribution is an alternative to the detailed 3D modelling of the screws using solid elements and simplified approaches which use spring elements at each screw location. The screws were modelled using one-dimensional beam element, while the timber and concrete members were modelled, in detail, using 3D solid elements. To deal with the coupling between the common nodes, the 4-node beam element with only translational degrees of freedom (d.o.f.) per node, recently developed by the authors [1,2], has been extended to nonlinear analysis and employed to model the screws, since the existing 2-node beam element is obviously not fulfilled for screws in timber [2]. The effectiveness of the numerical model developed was verified experimentally showing several advantages by comparison to the existing models in the literature. © 2013 Elsevier Ltd.


Meghlat E.-M.,Mouloud Mammeri University | Oudjene M.,CNRS Wood Materials Research Laboratory | Ait-Aider H.,Mouloud Mammeri University | Batoz J.-L.,Center Pierre Guillaumat 2
Construction and Building Materials | Year: 2013

This paper presents a novel way to simulate the behaviour of nailed and screwed timber joints, using the finite element method. In order to avoid the detailed 3D modelling of nails (or screws) using solid elements, which is costly ineffective, the authors proposed and developed an approach based on beam-to-solid coupling where the nails (or screws) were modelled using one-dimensional beam element, while the assembled timber members were modelled using solid elements. To deal with the coupling between the degrees of freedom (d.o.f.) belonging to the screws and those belonging to the timber, the existing 2-node beam element has been modified involving in a 4-node beam element with only translational d.o.f. per node, leading in fact to a full compatibility with solid elements. Using the numerical approach developed, the linear elastic behaviour of a push-out shear test of a single shear timber-to-timber connection was successfully simulated.©2012 Elsevier Ltd. All rights reserved.


Brahim M.,CNRS Wood Materials Research Laboratory | Gambier F.,CNRS Wood Materials Research Laboratory | Brosse N.,CNRS Wood Materials Research Laboratory
Industrial Crops and Products | Year: 2014

The extraction in water of polyphenolics from grape red marc, grape white marc and grape pomace for the production of wood adhesives was optimized using microwave extraction in presence of Na2CO3. The reaction parameters studied were the temperature (60-120°C), the residence time (5-20min) and the sodium carbonate concentration (0-2.5%) using response surface methodology based on central composite design. The optimal values of the variables were as the followings: 100°C, 8min, without sodium carbonate from grape marcs and 100°C, 8min, 2.5% w/w of sodium carbonate for pomace. The microwave assisted extractions gave significantly higher yields as compared to traditional extraction and could be recommended as an alternative method for extraction of phenolic compounds from grape residues in water medium. © 2013 Elsevier B.V.


Abdallah R.,CNRS Wood Materials Research Laboratory | Auchet S.,CNRS Wood Materials Research Laboratory | Meausoone P.J.,CNRS Wood Materials Research Laboratory
Biomass and Bioenergy | Year: 2011

Nowadays wood should be of principal sources of biomass. This wood is transformed into chips in order to increase automatic operations and to decrease the technical effort needed at the energy conversion plant. Typical high quality chips, which are used to feed small woodchip boilers, vary in size from 10 × 10 × 5 mm to 15 × 15 × 8 mm. Chips that are relatively square and flat are easily conveyed, augured, and fed into the system smoothly. We are mainly interested in the raw material of inferior quality. A disc chipper test bench was constructed in our laboratory to study the chipping process in cutting conditions which are similar to those used in the industry. The test bench design allows many factors to be varied include cutting speed, feed per tooth, cutting angles, anvil height and cutting direction. In this paper, we attempt to understand the effect of several factors on chip size distribution. Four feeds per tooth, four cutting angles, two sharpness angles and three cutting speeds were chosen to cut wet logs of oak and fir wood, while the other factors remained constant. The results are similar for both oak and fir. The proportion of small chips decreases when we increase the feed per tooth, the cutting angle and the sharpness angle, whereas it increases when the cutting speed is increased. The feed per tooth and the cutting speed have a linear effect on the variations in the size distribution, while the cutting angle has a non-linear effect on these variations. © 2010 Elsevier Ltd.


Tran V.-D.,CNRS Wood Materials Research Laboratory | Oudjene M.,CNRS Wood Materials Research Laboratory | Meausoone P.-J.,CNRS Wood Materials Research Laboratory
Composite Structures | Year: 2015

The aim of this work was to study the behaviour of adhesively reconstituted beams made of local beech timber. Experimental and numerical results are presented. Contributions of numerical modelling for the analysis of adhesively bonded assemblies for beech timber components are the main focus of the present paper. Numerical simulations are based on the Cohesive Zone Model (CZM) of Abaqus software to allow for accurate description of the progressive damage of the bond-lines up to final failure. The effects of several parameters were investigated ones the finite element model has been verified against experiments. The numerical results have showed that the modelling approach was convenient to study the behaviour of such beam systems with limited destructive tests, which are likely to be very expensive and time consuming. The parametrical study undertaken demonstrated a significant enhancement of the load-carrying capacity of beams by optimising the finger-jointing geometry. © 2014 Elsevier Ltd.

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