The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Patrick Perre - One of the best experts on this subject based on the ideXlab platform.
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Finite element analysis of stress-related degrade during Drying of Corymbia citriodora and Eucalyptus obliqua
Wood Science and Technology, 2018Co-Authors: Adam L. Redman, Henri Bailleres, Benoit P. Gilbert, Elliot J. Carr, Ian W. Turner, Patrick PerreAbstract:With the use of experimental Wood properties and input moisture content field data, a predictive 3D stress–strain finite element analysis (FEA) model was developed allowing to predict the development of stress-related end splitting and surface checking degrade during conventional and vacuum Wood Drying. Simulations were carried out for two Australian hardWood species, messmate ( Eucalyptus obliqua ) and spotted gum ( Corymbia citriodora ), as these species contrast, in terms of Wood properties, Drying rates and stress degrade susceptibility. The simulations were performed using a 1/8 symmetry model where the full board dimensions are 1900 mm long × 30 mm thick × 100 mm wide. Moisture content field data model simulations were utilised in a three-dimensional FEA model by extruding a 2D moisture content field computed in the T – L plane across the radial direction to create a 3D model. Material mechanical properties and shrinkage were calculated in relation to moisture content, over discrete time intervals, using a quasi-static solver. End split failure was investigated at the board end, and surface check failure at the board surface, using a Tsai–Wu failure criterion. Simulations showed that messmate was more susceptible to end splitting than spotted gum and that conventionally dried messmate was more susceptible to surface checking than vacuum-dried messmate. The same results were observed from Drying trials. The locations of predicted surface check failure also matched Drying trials and are compared.
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Numerical investigation of Wood Drying with intermittent energy source at low exergy content
2014Co-Authors: Romain Remond, Patrick PerreAbstract:The possibility to dry heat-sensitive timber with solar energy or residual energy from industrial processes with low exergy content, may be of double interest: the use of energy sources with very low price and the reduction of thermal pollution. The important issue when using such energies is to adapt the process control to the availability of the energy. Additionally, there is a major concern that this energy saving could be done at the detriment of Drying quality or Drying time. This paper proposes a numerical investigation of the possibility to use intermittent energy source to dry Wood Drying by comparing different strategies.
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reaction Wood Drying kinetics tension Wood in fagus sylvatica and compression Wood in picea abies
Wood Science and Technology, 2009Co-Authors: Asghar Tarmian, Romain Remond, Mehdi Faezipour, Ali Karimi, Patrick PerreAbstract:The Drying kinetics of reaction Woods in Picea abies (compression Wood) and Fagus sylvatica (tension Wood) in comparison with their corresponding normal Woods was investigated under constant convective Drying conditions. Moisture profiles along the thickness of small flat-sawn boards taken from reaction and opposite Wood zones were evaluated using a polychromatic X-ray system, a non-destructive method. The results revealed substantial differences in the Drying behavior between the reaction and opposite Woods. Both reaction Woods represented slower Drying rate than their matching normal Woods mainly during the period of free water loss. However, the reaction and opposite Woods reached the final moisture content (MC) of about 12% at the same time due to higher initial MC in the opposite Woods. In the case of reaction Wood, it took a longer time for the moisture profile to become approximately uniform. Overall, a more striking difference was observed in the Drying behavior of compression and opposite Wood in P. abies. Some important anatomical differences like the cell and pit dimensions and their proportion give some explanations for these Drying behaviors.
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a physical and mechanical model able to predict the stress field in Wood over a wide range of Drying conditions
Drying Technology, 2004Co-Authors: Patrick Perre, Joelle PassardAbstract:Abstract Drying is an essential operation of the Wood industry. Computational models of Wood Drying appeared several decades ago. They started with just mass transfer in one dimension. Nowadays, comprehensive models exist, that can deal with three dimensions and comprehensive physical and mechanical formulation. Provided a comprehensive approach is usual (species characterization, mathematical modeling, computational simulation, and model validation), the computational model is a tool that is now used not only to improve existing procedures but also to imagine and tune innovative processes. Two examples are proposed, that allows the importance of the mechanical characterization to be exhibited: – To take advantage of the viscoelastic behavior of Wood, and its hydro-thermal activation, to reduce significantly the Drying time with the same quality of the dried product. – To compare the efficiency of two different Drying schedules with informative conclusions.
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the use of implicit flux limiting schemes in the simulation of the Drying process a new maximum flow sensor applied to phase mobilities
Applied Mathematical Modelling, 2001Co-Authors: Ian Turner, Patrick PerreAbstract:Abstract In this work, a previously proposed two-dimensional Wood Drying computational model is modified so that an analysis of the use of flux limiters for reducing numerical dispersion in the Drying kinetics can be undertaken. In particular, a new sensor based on the ratio of phase fluxes is used to flux limit the liquid and gas phase mobility tensors. An extremely important physical phenomenon that arises during high temperature Drying, and one that is exacerbated by the use of the flux limiter, relates to the medium becoming fully saturated. To overcome the numerical convergence problems associated with this phenomenon, the concept of a fixed compressible phase is introduced within the model and the averaged air density is used as one of the primary solution variables. A comparison of the simulation results for high temperature Drying will be presented for three different case studies. In case one, a completely isotropic sample is considered while in case two, a slight anisotropy (1:2) is introduced for the modelling of a radial–transverse Wood cross-section. In case three, for a Wood sample modelled in the radial–longitudinal cross-section, a strongly anisotropic medium (1:1000) is analysed. It is found in all cases that when the new sensor is used during flux limiting, superior results to upstream weighting are obtained. In fact, it is possible with this method to attain the accuracy offered by upstream weighting on a much finer mesh at a considerable reduction of at least a factor of 5 in the overall computation time.
Fred Willians Calonego - One of the best experts on this subject based on the ideXlab platform.
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physical and mechanical properties of thermally modified Wood from e grandis
European Journal of Wood and Wood Products, 2012Co-Authors: Fred Willians Calonego, Elias Taylor Durgante Severo, Adriano Wagner BallarinAbstract:This study was aimed at evaluating the effect of thermal treatment on the physical and mechanical properties of Eucalyptus grandis Wood. Boards were taken from 5.9-year-old E. grandis trees. The boards were thermally modified at temperatures up to 220°C in the Laboratory of Wood Drying and Preservation from UNESP, Botucatu, SP, in Brazil. The results indicated that the thermal modification caused significant decreases of up to: (1) 49.3% and 10.5% in the equilibrium moisture content and in the density of Wood, respectively; (2) 53.3% in the volumetric swelling; (3) 52.3% in the modulus of rupture at static bending, without changes in the compressive strength parallel to grain and the respective modulus of elasticity; and (4) 20.7% in the Janka hardness. It was found that the specific gravity and compression parallel to the grain test were not the most suitable ones for evaluating the quality of thermally modified Wood.
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decay resistance of thermally modified eucalyptus grandis Wood at 140 c 160 c 180 c 200 c and 220 c
Bioresource Technology, 2010Co-Authors: Fred Willians Calonego, Elias Taylor Durgante Severo, Edson Luiz FurtadoAbstract:Abstract The objective of this study was to evaluate the effect of thermal treatment on the biological resistance of Eucalyptus grandis Wood to the decay fungus Picnoporus sanguineus . Boards from 5 years and 11 months old E. grandis trees, taken from the stock possessed by the Duratex-SA company, were thermally-modified at 140 °C, 160 °C, 180 °C, 200 °C and 220 °C in the Laboratory of Wood Drying and Preservation from UNESP, Botucatu, SP, Brazil. Samples of each treatment were treated according to ASTM D-2017 (1994) . The experiment tested the accelerated decay caused by the decay fungus P. sanguineus on a system of soil-block Wood. The results of thermal treatment showed that an increase of temperature of 180–220 °C caused reductions of between 15.7% and 82.4% in the weight loss in the samples from E. grandis incubated with P. sanguineus .
Youke Zhao - One of the best experts on this subject based on the ideXlab platform.
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studies on pre treatment by compression for Wood Drying iii the reduction of moisture content the recovery rate and mechanical properties of Wood compressed at different moisture content conditions
Journal of Wood Science, 2017Co-Authors: Youke ZhaoAbstract:As a follow-up report, the pre-treatment by compression for Wood Drying was systematically studied in terms of the reduction of moisture content (MC), the recovery rate (RR), and mechanical properties of Wood compressed at different MC conditions. The results showed that MC after compression on water-saturated Wood determined the critical value of MC before compression which were about 84 and 105% at a compression ratio of 60 and 40% for Poplar and Chinese fir, respectively. Beyond the critical value, MC after compression remained constantly at about 84% and decreased slightly from 105% for Poplar and Chinese fir, respectively. The MC reduction decreased with the decrease of MC before compression. The MC reduction was rather effective when the MC before compression was higher than the critical value and was recommended to pre-treat for the effectiveness of MC reduction. In addition, after the recovery, the Wood volume and mechanical properties were well retained for the Wood compressed at all MC conditions which were above fiber saturation point (FSP) before and after compression. Therefore, the pre-treatment by compression is viable in terms of the RR and mechanical properties at rather broad MC conditions above FSP. Moreover, the compression force needed for treatment was almost same at these MC conditions.
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studies on pre treatment by compression for Wood Drying ii effects of compression ratio compression direction and compression speed on the recovery rate and mechanical properties of Wood
Journal of Wood Science, 2016Co-Authors: Youke Zhao, Zhihui Wang, Ikuho Iida, Rongfeng Huang, Jianxiong Lu, Jinghui JiangAbstract:As a follow-up report, the pre-treatment by compression for Wood Drying was systematically studied in terms of effects of compression ratio, compression direction and compression speed on the recovery rate (RR) and mechanical properties. The results showed: the RR decreased 0.18 and 0.20 % every 1 % compression ratio when the compression ratio was lower than or equal to 50 and 40 % for Poplar and Chinese fir, respectively, over this compression ratio, the RR decreased rapidly; the RR had the maximum value in tangential compression for Poplar, while had the minimum value in 45° compression for Chinese fir; the RR of specimens compressed at 3, 5 and 10 mm/min were bigger than those in 0.5 and 1 mm/min for Poplar. For Chinese fir, the RR difference among all the compression speed was quite small compared with that for Poplar. The RR at all conditions was no less than 73.3 and 79.7 % for Poplar and Chinese fir, respectively; The mechanical properties difference was not significant between the specimen compressed in different compression ratio, while was significant between the specimens compressed in different direction and different speed except the modulus of rupture (MOR) of Poplar between different compression direction. For Chinese fir, MOR and modulus of elasticity (MOE) in 45° compression specimen showed the maximum value. The mechanical properties at all conditions retained at least 83.1 and 88.1 % of MOR, 84.9 and 83.7 % of MOE for Poplar and Chinese fir, respectively. After all, the pre-treatment by compression for Wood Drying is viable in terms of RR and mechanical properties at all compression ratio, compression direction and compression speed we tested.
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studies on pre treatment by compression for Wood Drying i effects of compression ratio compression direction and compression speed on the reduction of moisture content in Wood
Journal of Wood Science, 2015Co-Authors: Youke Zhao, Zhihui Wang, Ikuho Iida, Rongfeng Huang, Jianxiong Lu, Jinghui JiangAbstract:To remarkably reduce the moisture content (MC) in a short time, pre-treatment by compression for Wood Drying was systematically studied in terms of effects of compression ratio, compression direction and compression speed on the reduction of MC in Poplar and Chinese fir. The results showed (1) MC reduction was about 108 and 176 % after compression at a ratio of 60 % from water-saturated condition, and it was about 1.8 and 3.0 % every 1 % compression ratio for Poplar and Chinese fir, respectively. (2) Compressions in tangential, radial and 45° direction were very effective in MC reduction, suggesting that pre-treatment by compression is very effective on round Wood and timbers of flat grain, vertical grain and in-between vertical and flat grain. Of all the compression directions, the tangential compression showed a maximum MC reduction. (3) For Poplar, when the compression speed was 0.5, 1 and 3 mm/min, MC reduction had no big change; while it became small when the compression speed was 5 and 10 mm/min. For Chinese fir, reduction of MC decreased with the increase in compression speed. After all, the pre-treatment by compression is very effective to reduce the MC for Wood Drying.
Edson Luiz Furtado - One of the best experts on this subject based on the ideXlab platform.
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decay resistance of thermally modified eucalyptus grandis Wood at 140 c 160 c 180 c 200 c and 220 c
Bioresource Technology, 2010Co-Authors: Fred Willians Calonego, Elias Taylor Durgante Severo, Edson Luiz FurtadoAbstract:Abstract The objective of this study was to evaluate the effect of thermal treatment on the biological resistance of Eucalyptus grandis Wood to the decay fungus Picnoporus sanguineus . Boards from 5 years and 11 months old E. grandis trees, taken from the stock possessed by the Duratex-SA company, were thermally-modified at 140 °C, 160 °C, 180 °C, 200 °C and 220 °C in the Laboratory of Wood Drying and Preservation from UNESP, Botucatu, SP, Brazil. Samples of each treatment were treated according to ASTM D-2017 (1994) . The experiment tested the accelerated decay caused by the decay fungus P. sanguineus on a system of soil-block Wood. The results of thermal treatment showed that an increase of temperature of 180–220 °C caused reductions of between 15.7% and 82.4% in the weight loss in the samples from E. grandis incubated with P. sanguineus .
Jinghui Jiang - One of the best experts on this subject based on the ideXlab platform.
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studies on pre treatment by compression for Wood Drying ii effects of compression ratio compression direction and compression speed on the recovery rate and mechanical properties of Wood
Journal of Wood Science, 2016Co-Authors: Youke Zhao, Zhihui Wang, Ikuho Iida, Rongfeng Huang, Jianxiong Lu, Jinghui JiangAbstract:As a follow-up report, the pre-treatment by compression for Wood Drying was systematically studied in terms of effects of compression ratio, compression direction and compression speed on the recovery rate (RR) and mechanical properties. The results showed: the RR decreased 0.18 and 0.20 % every 1 % compression ratio when the compression ratio was lower than or equal to 50 and 40 % for Poplar and Chinese fir, respectively, over this compression ratio, the RR decreased rapidly; the RR had the maximum value in tangential compression for Poplar, while had the minimum value in 45° compression for Chinese fir; the RR of specimens compressed at 3, 5 and 10 mm/min were bigger than those in 0.5 and 1 mm/min for Poplar. For Chinese fir, the RR difference among all the compression speed was quite small compared with that for Poplar. The RR at all conditions was no less than 73.3 and 79.7 % for Poplar and Chinese fir, respectively; The mechanical properties difference was not significant between the specimen compressed in different compression ratio, while was significant between the specimens compressed in different direction and different speed except the modulus of rupture (MOR) of Poplar between different compression direction. For Chinese fir, MOR and modulus of elasticity (MOE) in 45° compression specimen showed the maximum value. The mechanical properties at all conditions retained at least 83.1 and 88.1 % of MOR, 84.9 and 83.7 % of MOE for Poplar and Chinese fir, respectively. After all, the pre-treatment by compression for Wood Drying is viable in terms of RR and mechanical properties at all compression ratio, compression direction and compression speed we tested.
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studies on pre treatment by compression for Wood Drying i effects of compression ratio compression direction and compression speed on the reduction of moisture content in Wood
Journal of Wood Science, 2015Co-Authors: Youke Zhao, Zhihui Wang, Ikuho Iida, Rongfeng Huang, Jianxiong Lu, Jinghui JiangAbstract:To remarkably reduce the moisture content (MC) in a short time, pre-treatment by compression for Wood Drying was systematically studied in terms of effects of compression ratio, compression direction and compression speed on the reduction of MC in Poplar and Chinese fir. The results showed (1) MC reduction was about 108 and 176 % after compression at a ratio of 60 % from water-saturated condition, and it was about 1.8 and 3.0 % every 1 % compression ratio for Poplar and Chinese fir, respectively. (2) Compressions in tangential, radial and 45° direction were very effective in MC reduction, suggesting that pre-treatment by compression is very effective on round Wood and timbers of flat grain, vertical grain and in-between vertical and flat grain. Of all the compression directions, the tangential compression showed a maximum MC reduction. (3) For Poplar, when the compression speed was 0.5, 1 and 3 mm/min, MC reduction had no big change; while it became small when the compression speed was 5 and 10 mm/min. For Chinese fir, reduction of MC decreased with the increase in compression speed. After all, the pre-treatment by compression is very effective to reduce the MC for Wood Drying.