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Patrick Perré - One of the best experts on this subject based on the ideXlab platform.
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, A CUSTOM DEVICE ABLE TO MEASURE VISCOELASTIC PROPERTIES OF WOOD UNDER WATER-Saturated Conditions (* WAVE
2020Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:This work presents an original experimental device conceived to characterise the viscoelastic properties of wood. Classically, the dynamic mechanical analysis of wood is performed using a commercial apparatus like a DMA (Dynamic Mechanical Analyser). However, when analysing wood with this type of apparatus, many problems related to the hygroscopic behaviour and the orthotropic structure of wood may be encountered. This is why an original apparatus perfectly adapted to the wood features has been developed. The WAVE T is able to measure the viscoelastic properties of wood samples under water-Saturated Conditions, in the temperature range of 5°C to 95°C at frequencies varying between 0.005 Hz and 10 Hz. Samples are tested in a cantilever confi guration. The whole experiment has been designed to withstand the severe Conditions of temperature and humidity. At the same time, an analytical model based on Kelvin's elements has been developed. This model is able to correct experimental measurements performed close to the resonance frequency. Results obtained for beech samples in radial and tangential directions using the WAVE T and a commercial apparatus (DMA 2980 TA Instruments) are compared and discussed. This comparison underlines the relevance of the WAVE T device.
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Wavet, a Custom Device Able to Measure Viscoelastic Properties of Wood Under Water-Saturated Conditions Up to 140 deg C (WAVET : Environmental Vibration Analyser for Wood)
arXiv: Materials Science, 2009Co-Authors: Vincent Placet, Patrick PerréAbstract:This work presents an innovative experimental device conceived to characterize the time-dependent behavior of hygroscopic materials, as wood, at controlled moisture content and temperature. This device, the WAVET, permits the determination of the viscoelastic properties of samples, using harmonic tests at frequencies varying from 5.10-3 Hz to 10 Hz. Conceived to work up to 5 bar, it allows tests in dry or water-Saturated Conditions to be performed over the temperature range 0\degree C to 140\degree C. In spite of these severe working Conditions, the careful device design, together with a rigorous data analysis, allows a rigorous determination of the storage and loss modulus and the loss factor. The results collected for several species of wood emphasize the ability of the WAVET to underline the influence of numerous parameters, namely specie, material direction, anatomical and macromolecular structure, on the rheological properties and notably on the softening temperature. The WAVET also establishes a efficient tool to follow the modifications of the constitutive amorphous polymers of materials submitted to hydrothermal treatments, in relation to the evolution of their viscoelastic properties.
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Viscoelastic properties of wood across the grain measured under water-Saturated Conditions up to 135 °C: evidence of thermal degradation
Journal of Materials Science, 2008Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:In this paper, the viscoelastic properties of wood under water-Saturated Conditions are investigated from 10 to 135 °C using the WAVE^T apparatus. Experiments were performed via harmonic tests at two frequencies (0.1 and 1 Hz) for several hours. Four species of wood were tested in the radial and tangential material directions: oak ( Quercus sessiliflora ), beech ( Fagus sylvatica ), spruce ( Picea abies ) and fir ( Abies pectinata ). When the treatment is applied for several hours, a reduction of the wood rigidity is significant from temperature values as low as 80–90 °C and increases rapidly with the temperature level. The storage modulus of oak wood is divided by a factor two after 3 h of exposure at 135 °C. This marked reduction in rigidity is attributed to the hydrolysis of hemicelluloses. The softening temperature of wood is also noticeably affected by hygro-thermal treatment. After three short successive treatments up to 135 °C, the softening temperature of oak shifted from 79 °C to 103 °C, at a frequency of 1 Hz. This reduction in mobility of wood polymers is consistent with the condensation of lignins observed by many authors at this temperature level. In the same Conditions, fir exhibited a softening temperature decrease of about 4 °C. In any case, the internal friction clearly rises.
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WAVET, A CUSTOM DEVICE ABLE TO MEASURE VISCOELASTIC PROPERTIES OF WOOD UNDER WATER-Saturated Conditions UP TO 140°C (WAVET : ENVIRONMENTAL VIBRATION ANALYSER FOR WOOD)
2008Co-Authors: Vincent Placet, Patrick PerréAbstract:This work presents an innovative experimental device conceived to characterize the time-dependent behavior of hygroscopic materials, as wood, at controlled moisture content and temperature. This device, the WAVET, permits the determination of the viscoelastic properties of samples, using harmonic tests at frequencies varying from 5.10-3 Hz to 10 Hz. Conceived to work up to 5 bar, it allows tests in dry or water-Saturated Conditions to be performed over the temperature range 0°C to 140°C. In spite of these severe working Conditions, the careful device design, together with a rigorous data analysis, allows a rigorous determination of the storage and loss modulus and the loss factor. The results collected for several species of wood emphasize the ability of the WAVET to underline the influence of numerous parameters, namely specie, material direction, anatomical and macromolecular structure, on the rheological properties and notably on the softening temperature. The WAVET also establishes a efficient tool to follow the modifications of the constitutive amorphous polymers of materials submitted to hydrothermal treatments, in relation to the evolution of their viscoelastic properties.
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WAVE T*, a custom device able to measure viscoelastic properties of wood under water-Saturated Conditions (*WAVE T : Environmental Vibration Analyser for Wood)
Maderas-ciencia Y Tecnologia, 2008Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:This work presents an original experimental device conceived to characterise the viscoelastic properties of wood. Classically, the dynamic mechanical analysis of wood is performed using a commercial apparatus like a DMA (Dynamic Mechanical Analyser). However, when analysing wood with this type of apparatus, many problems related to the hygroscopic behaviour and the orthotropic structure of wood may be encountered. This is why an original apparatus perfectly adapted to the wood features has been developed. The WAVET is able to measure the viscoelastic properties of wood samples under water-Saturated Conditions, in the temperature range of 5°C to 95°C at frequencies varying between 0.005 Hz and 10 Hz. Samples are tested in a cantilever configuration. The whole experiment has been designed to withstand the severe Conditions of temperature and humidity.At the same time, an analytical model based on Kelvin’s elements has been developed. This model is able to correct experimental measurements performed close to the resonance frequency.Results obtained for beech samples in radial and tangential directions using the WAVET and a commercial apparatus (DMA 2980 TA Instruments) are compared and discussed. This comparison underlines the relevance of the WAVET device.
Vincent Placet - One of the best experts on this subject based on the ideXlab platform.
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, A CUSTOM DEVICE ABLE TO MEASURE VISCOELASTIC PROPERTIES OF WOOD UNDER WATER-Saturated Conditions (* WAVE
2020Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:This work presents an original experimental device conceived to characterise the viscoelastic properties of wood. Classically, the dynamic mechanical analysis of wood is performed using a commercial apparatus like a DMA (Dynamic Mechanical Analyser). However, when analysing wood with this type of apparatus, many problems related to the hygroscopic behaviour and the orthotropic structure of wood may be encountered. This is why an original apparatus perfectly adapted to the wood features has been developed. The WAVE T is able to measure the viscoelastic properties of wood samples under water-Saturated Conditions, in the temperature range of 5°C to 95°C at frequencies varying between 0.005 Hz and 10 Hz. Samples are tested in a cantilever confi guration. The whole experiment has been designed to withstand the severe Conditions of temperature and humidity. At the same time, an analytical model based on Kelvin's elements has been developed. This model is able to correct experimental measurements performed close to the resonance frequency. Results obtained for beech samples in radial and tangential directions using the WAVE T and a commercial apparatus (DMA 2980 TA Instruments) are compared and discussed. This comparison underlines the relevance of the WAVE T device.
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Wavet, a Custom Device Able to Measure Viscoelastic Properties of Wood Under Water-Saturated Conditions Up to 140 deg C (WAVET : Environmental Vibration Analyser for Wood)
arXiv: Materials Science, 2009Co-Authors: Vincent Placet, Patrick PerréAbstract:This work presents an innovative experimental device conceived to characterize the time-dependent behavior of hygroscopic materials, as wood, at controlled moisture content and temperature. This device, the WAVET, permits the determination of the viscoelastic properties of samples, using harmonic tests at frequencies varying from 5.10-3 Hz to 10 Hz. Conceived to work up to 5 bar, it allows tests in dry or water-Saturated Conditions to be performed over the temperature range 0\degree C to 140\degree C. In spite of these severe working Conditions, the careful device design, together with a rigorous data analysis, allows a rigorous determination of the storage and loss modulus and the loss factor. The results collected for several species of wood emphasize the ability of the WAVET to underline the influence of numerous parameters, namely specie, material direction, anatomical and macromolecular structure, on the rheological properties and notably on the softening temperature. The WAVET also establishes a efficient tool to follow the modifications of the constitutive amorphous polymers of materials submitted to hydrothermal treatments, in relation to the evolution of their viscoelastic properties.
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Viscoelastic properties of wood across the grain measured under water-Saturated Conditions up to 135 °C: evidence of thermal degradation
Journal of Materials Science, 2008Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:In this paper, the viscoelastic properties of wood under water-Saturated Conditions are investigated from 10 to 135 °C using the WAVE^T apparatus. Experiments were performed via harmonic tests at two frequencies (0.1 and 1 Hz) for several hours. Four species of wood were tested in the radial and tangential material directions: oak ( Quercus sessiliflora ), beech ( Fagus sylvatica ), spruce ( Picea abies ) and fir ( Abies pectinata ). When the treatment is applied for several hours, a reduction of the wood rigidity is significant from temperature values as low as 80–90 °C and increases rapidly with the temperature level. The storage modulus of oak wood is divided by a factor two after 3 h of exposure at 135 °C. This marked reduction in rigidity is attributed to the hydrolysis of hemicelluloses. The softening temperature of wood is also noticeably affected by hygro-thermal treatment. After three short successive treatments up to 135 °C, the softening temperature of oak shifted from 79 °C to 103 °C, at a frequency of 1 Hz. This reduction in mobility of wood polymers is consistent with the condensation of lignins observed by many authors at this temperature level. In the same Conditions, fir exhibited a softening temperature decrease of about 4 °C. In any case, the internal friction clearly rises.
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WAVET, A CUSTOM DEVICE ABLE TO MEASURE VISCOELASTIC PROPERTIES OF WOOD UNDER WATER-Saturated Conditions UP TO 140°C (WAVET : ENVIRONMENTAL VIBRATION ANALYSER FOR WOOD)
2008Co-Authors: Vincent Placet, Patrick PerréAbstract:This work presents an innovative experimental device conceived to characterize the time-dependent behavior of hygroscopic materials, as wood, at controlled moisture content and temperature. This device, the WAVET, permits the determination of the viscoelastic properties of samples, using harmonic tests at frequencies varying from 5.10-3 Hz to 10 Hz. Conceived to work up to 5 bar, it allows tests in dry or water-Saturated Conditions to be performed over the temperature range 0°C to 140°C. In spite of these severe working Conditions, the careful device design, together with a rigorous data analysis, allows a rigorous determination of the storage and loss modulus and the loss factor. The results collected for several species of wood emphasize the ability of the WAVET to underline the influence of numerous parameters, namely specie, material direction, anatomical and macromolecular structure, on the rheological properties and notably on the softening temperature. The WAVET also establishes a efficient tool to follow the modifications of the constitutive amorphous polymers of materials submitted to hydrothermal treatments, in relation to the evolution of their viscoelastic properties.
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WAVE T*, a custom device able to measure viscoelastic properties of wood under water-Saturated Conditions (*WAVE T : Environmental Vibration Analyser for Wood)
Maderas-ciencia Y Tecnologia, 2008Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:This work presents an original experimental device conceived to characterise the viscoelastic properties of wood. Classically, the dynamic mechanical analysis of wood is performed using a commercial apparatus like a DMA (Dynamic Mechanical Analyser). However, when analysing wood with this type of apparatus, many problems related to the hygroscopic behaviour and the orthotropic structure of wood may be encountered. This is why an original apparatus perfectly adapted to the wood features has been developed. The WAVET is able to measure the viscoelastic properties of wood samples under water-Saturated Conditions, in the temperature range of 5°C to 95°C at frequencies varying between 0.005 Hz and 10 Hz. Samples are tested in a cantilever configuration. The whole experiment has been designed to withstand the severe Conditions of temperature and humidity.At the same time, an analytical model based on Kelvin’s elements has been developed. This model is able to correct experimental measurements performed close to the resonance frequency.Results obtained for beech samples in radial and tangential directions using the WAVET and a commercial apparatus (DMA 2980 TA Instruments) are compared and discussed. This comparison underlines the relevance of the WAVET device.
Shunichiro Karato - One of the best experts on this subject based on the ideXlab platform.
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low temperature high stress deformation of olivine under water Saturated Conditions
Physics of the Earth and Planetary Interiors, 2008Co-Authors: Ikuo Katayama, Shunichiro KaratoAbstract:Abstract Low-temperature high-stress rheology of olivine was investigated under water-Saturated Conditions by large strain shear deformation experiments using the Griggs-type apparatus. Samples at T = 1273–1373 K and P = 2 GPa under water-Saturated Conditions deformed under a significantly lower applied stress than expected from the power-law relation and the strain rate increases more rapidly with stress. These observations suggest that an exponential flow law operates under the present experimental Conditions, in which the stress dependence of activation enthalpy is characterized by the Peierls stress. The Peierls stress is determined between 1.6 and 2.9 GPa depending on the choice of the form of stress dependence of the activation enthalpy. These values are significantly smaller than the Peierls stress under dry Conditions (9.1 GPa). We suggest that water (hydrogen) incorporated in the olivine lattices decreases the Peierls stress, and hence the rate of deformation in the exponential creep is significantly enhanced by the presence of water. The reduction of the Peierls stress by water results in the highly anisotropic weakening effect of water that causes the fabric transitions in olivine. The transition between the power-law and the exponential creep occurs at relatively low stress ∼100 MPa at a geologically relevant strain rate of 10 −15 s −1 when temperature is lower than 1273 K and under water-rich Conditions. Hence, the exponential creep might be dominated in olivine-rich rocks at low-temperature and high-stress under water-rich Conditions, and such regions could be widespread in the subduction zone upper mantle where the cold lithospheric plates sink into the mantle.
D R Blake - One of the best experts on this subject based on the ideXlab platform.
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ozone production in the upper troposphere and the influence of aircraft during sonex approach of nox Saturated Conditions
Geophysical Research Letters, 1999Co-Authors: L Jaegle, Daniel J Jacob, W H Brune, I C Faloona, Y Kondo, G W Sachse, B E Anderson, G L Gregory, H B Singh, D R BlakeAbstract:During October/November 1997, simultaneous observations of NO, HO2 and other species were obtained as part of the SONEX campaign in the upper troposphere. We use these observations, over the North Atlantic (40-60°N), to derive ozone production rates, P(O3), and to examine the relationship between P(O3) and the concentrations of NOx (= NO + NO2) and HOx (= OH + peroxy) radicals. A positive correlation is found between P(O3) and NOx over the entire data set, which reflects the association of elevated HOx with elevated NOx injected by deep convection and lightning. By filtering out this association we find that for NOx>70 pptv, P(O3) is nearly independent of NOx, showing the approach of NOx-Saturated Conditions. Predicted doubling of aircraft emissions in the future will result in less than doubling of the aircraft contribution to ozone over the North Atlantic in the fall. Greater sensitivity to aircraft emissions would be expected in the summer.
Joëlle Passard - One of the best experts on this subject based on the ideXlab platform.
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, A CUSTOM DEVICE ABLE TO MEASURE VISCOELASTIC PROPERTIES OF WOOD UNDER WATER-Saturated Conditions (* WAVE
2020Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:This work presents an original experimental device conceived to characterise the viscoelastic properties of wood. Classically, the dynamic mechanical analysis of wood is performed using a commercial apparatus like a DMA (Dynamic Mechanical Analyser). However, when analysing wood with this type of apparatus, many problems related to the hygroscopic behaviour and the orthotropic structure of wood may be encountered. This is why an original apparatus perfectly adapted to the wood features has been developed. The WAVE T is able to measure the viscoelastic properties of wood samples under water-Saturated Conditions, in the temperature range of 5°C to 95°C at frequencies varying between 0.005 Hz and 10 Hz. Samples are tested in a cantilever confi guration. The whole experiment has been designed to withstand the severe Conditions of temperature and humidity. At the same time, an analytical model based on Kelvin's elements has been developed. This model is able to correct experimental measurements performed close to the resonance frequency. Results obtained for beech samples in radial and tangential directions using the WAVE T and a commercial apparatus (DMA 2980 TA Instruments) are compared and discussed. This comparison underlines the relevance of the WAVE T device.
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Viscoelastic properties of wood across the grain measured under water-Saturated Conditions up to 135 °C: evidence of thermal degradation
Journal of Materials Science, 2008Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:In this paper, the viscoelastic properties of wood under water-Saturated Conditions are investigated from 10 to 135 °C using the WAVE^T apparatus. Experiments were performed via harmonic tests at two frequencies (0.1 and 1 Hz) for several hours. Four species of wood were tested in the radial and tangential material directions: oak ( Quercus sessiliflora ), beech ( Fagus sylvatica ), spruce ( Picea abies ) and fir ( Abies pectinata ). When the treatment is applied for several hours, a reduction of the wood rigidity is significant from temperature values as low as 80–90 °C and increases rapidly with the temperature level. The storage modulus of oak wood is divided by a factor two after 3 h of exposure at 135 °C. This marked reduction in rigidity is attributed to the hydrolysis of hemicelluloses. The softening temperature of wood is also noticeably affected by hygro-thermal treatment. After three short successive treatments up to 135 °C, the softening temperature of oak shifted from 79 °C to 103 °C, at a frequency of 1 Hz. This reduction in mobility of wood polymers is consistent with the condensation of lignins observed by many authors at this temperature level. In the same Conditions, fir exhibited a softening temperature decrease of about 4 °C. In any case, the internal friction clearly rises.
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WAVE T*, a custom device able to measure viscoelastic properties of wood under water-Saturated Conditions (*WAVE T : Environmental Vibration Analyser for Wood)
Maderas-ciencia Y Tecnologia, 2008Co-Authors: Vincent Placet, Joëlle Passard, Patrick PerréAbstract:This work presents an original experimental device conceived to characterise the viscoelastic properties of wood. Classically, the dynamic mechanical analysis of wood is performed using a commercial apparatus like a DMA (Dynamic Mechanical Analyser). However, when analysing wood with this type of apparatus, many problems related to the hygroscopic behaviour and the orthotropic structure of wood may be encountered. This is why an original apparatus perfectly adapted to the wood features has been developed. The WAVET is able to measure the viscoelastic properties of wood samples under water-Saturated Conditions, in the temperature range of 5°C to 95°C at frequencies varying between 0.005 Hz and 10 Hz. Samples are tested in a cantilever configuration. The whole experiment has been designed to withstand the severe Conditions of temperature and humidity.At the same time, an analytical model based on Kelvin’s elements has been developed. This model is able to correct experimental measurements performed close to the resonance frequency.Results obtained for beech samples in radial and tangential directions using the WAVET and a commercial apparatus (DMA 2980 TA Instruments) are compared and discussed. This comparison underlines the relevance of the WAVET device.
