https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sun, 10 May 2026 01:43:56 GMT 2026-05-10T01:43:56Z http://hdl.handle.net/10985/14958 The influence of veneer thickness and knot proportion on the mechanical properties of laminated veneer lumber (LVL) made from secondary quality hardwood PURBA, Citra Yanto Ciki; RUELLE, Julien; DENAUD, Louis; POT, Guillaume; VIGUIER, Joffrey The first objective of this work was to study the influence of veneer quality on the mechanical properties of laminated veneer lumber (LVL) made of secondary quality hardwood. The second objective was to propose an adapted veneer thickness that provides the optimum mechanical properties of LVL, taking the veneer properties into account. Forty-eight LVL panels glued together using polyvinyl acetate (PVAc) were prepared. The quality of fresh veneers was assessed by measuring veneer knot proportion, lathe check depth and lathe check interval. The static modulus of elasticity (MOE), dynamic MOE, modulus of rupture (MOR) and shear modulus were measured using destructive and non-destructive methods. The 3 mm thick veneer provided the optimum mechanical properties for LVL for both species. The test direction did not have any significant influence on the mechanical properties. In the flatwise direction, the average MOE values obtained were 13.2 GPa for beech LVL and 13.3 GPa for oak LVL, whereas the MOR was 72.0 MPa and 63.4 MPa, respectively. Increasing knot proportion in veneers results in a decrease in LVL MOE and MOR. Moreover, deeper lathe checks and higher lathe check intervals on veneer surfaces provide lower LVL shear modulus in the edgewise direction for both species. Internal veneer provides LVL with a higher density but weaker mechanical properties due to a higher knot proportion in the internal veneer. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/14958 2019-01-01T00:00:00Z PURBA, Citra Yanto Ciki RUELLE, Julien DENAUD, Louis POT, Guillaume VIGUIER, Joffrey The first objective of this work was to study the influence of veneer quality on the mechanical properties of laminated veneer lumber (LVL) made of secondary quality hardwood. The second objective was to propose an adapted veneer thickness that provides the optimum mechanical properties of LVL, taking the veneer properties into account. Forty-eight LVL panels glued together using polyvinyl acetate (PVAc) were prepared. The quality of fresh veneers was assessed by measuring veneer knot proportion, lathe check depth and lathe check interval. The static modulus of elasticity (MOE), dynamic MOE, modulus of rupture (MOR) and shear modulus were measured using destructive and non-destructive methods. The 3 mm thick veneer provided the optimum mechanical properties for LVL for both species. The test direction did not have any significant influence on the mechanical properties. In the flatwise direction, the average MOE values obtained were 13.2 GPa for beech LVL and 13.3 GPa for oak LVL, whereas the MOR was 72.0 MPa and 63.4 MPa, respectively. Increasing knot proportion in veneers results in a decrease in LVL MOE and MOR. Moreover, deeper lathe checks and higher lathe check intervals on veneer surfaces provide lower LVL shear modulus in the edgewise direction for both species. Internal veneer provides LVL with a higher density but weaker mechanical properties due to a higher knot proportion in the internal veneer. http://hdl.handle.net/10985/18756 Contactless moisture content measurement on green veneer based on laser light scattering patterns PURBA, Citra Yanto Ciki; MARCON, Bertrand; DENAUD, Louis; VIGUIER, Joffrey The wood structure anisotropy and moisture content variation within the volume create different patterns of light scattering inside the wood. The objective of this study was to assess the suitability of a laser method for online measurement of green veneer moisture content based on the so-called tracheid effect. Beech and poplar veneers with thicknesses of 1, 2 and 3 mm were subsequently laser scanned and weighed to obtain various humidities. The results show that the measured laser scattering profile, such as the major axis, minor axis and ellipse area on the veneer surface, increases with moisture. The laser scattering profile provides a reliable and precise prediction of the moisture content. Out of the three ellipse parameters evaluated, the ellipse area provides the best prediction of the moisture content of the green veneer for both beech and poplar. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/10985/18756 2020-01-01T00:00:00Z PURBA, Citra Yanto Ciki MARCON, Bertrand DENAUD, Louis VIGUIER, Joffrey The wood structure anisotropy and moisture content variation within the volume create different patterns of light scattering inside the wood. The objective of this study was to assess the suitability of a laser method for online measurement of green veneer moisture content based on the so-called tracheid effect. Beech and poplar veneers with thicknesses of 1, 2 and 3 mm were subsequently laser scanned and weighed to obtain various humidities. The results show that the measured laser scattering profile, such as the major axis, minor axis and ellipse area on the veneer surface, increases with moisture. The laser scattering profile provides a reliable and precise prediction of the moisture content. Out of the three ellipse parameters evaluated, the ellipse area provides the best prediction of the moisture content of the green veneer for both beech and poplar. http://hdl.handle.net/10985/21716 Drying of green veneer hollow tubes monitored using stereo digital images correlation PURBA, Citra Yanto Ciki; MARCON, Bertrand; POMMIER, Régis; DENAUD, Louis; VIGUIER, Joffrey The present study is based on the patent FR3052379A1, which consists of rolling and gluing green veneers to form structural size hollow tubes. The objective was to study the drying behavior of circular hollow tubes and investigate the method of crack detection using image correlation from green conditions to equilibrium moisture content. The manufactured tubes are composed of six plies. Three different configurations of global grain angle orientations with respect to the tube longitudinal axis are used: {0, 0, 0}°, {10, 0, 10}°, and {− 10, 0, 10}°. Each grain angle was made up of two plies. The tubes deformation and crack formation due to drying shrinkage were measured using a stereo digital image correlation system. The stereo correlation is suitable for measuring tangential shrinkage and studying the opening and/or closing of cracks on the surface of the tubes subjected to internal moisture variations and blocked deformations. The influence of grain angle was discussedin this paper; however, due to the very few numbers of samples, no conclusive findings can be made. Sat, 01 Jan 2022 00:00:00 GMT http://hdl.handle.net/10985/21716 2022-01-01T00:00:00Z PURBA, Citra Yanto Ciki MARCON, Bertrand POMMIER, Régis DENAUD, Louis VIGUIER, Joffrey The present study is based on the patent FR3052379A1, which consists of rolling and gluing green veneers to form structural size hollow tubes. The objective was to study the drying behavior of circular hollow tubes and investigate the method of crack detection using image correlation from green conditions to equilibrium moisture content. The manufactured tubes are composed of six plies. Three different configurations of global grain angle orientations with respect to the tube longitudinal axis are used: {0, 0, 0}°, {10, 0, 10}°, and {− 10, 0, 10}°. Each grain angle was made up of two plies. The tubes deformation and crack formation due to drying shrinkage were measured using a stereo digital image correlation system. The stereo correlation is suitable for measuring tangential shrinkage and studying the opening and/or closing of cracks on the surface of the tubes subjected to internal moisture variations and blocked deformations. The influence of grain angle was discussedin this paper; however, due to the very few numbers of samples, no conclusive findings can be made. http://hdl.handle.net/10985/21995 Assessment of bonding durability of CLT and glulam made from oak and mixed poplar-oak according to bonding pressure and glue type PURBA, Citra Yanto Ciki; CHAPLAIN, Myriam; COUREAU, Jean-Luc; COLLET, Robert; POT, Guillaume The objective of this study is to evaluate the influence of manufacturing parameters on the bonding quality of CLT and glulam made from oak and mixing poplar and oak species. Studied bonding parameters were bonding pressure and glue type. To test the bonding durability, the specimens were subjected to a vacuum pressure cycle followed by drying to the initial weight. The bonding quality was then measured from delamination, residual shear strength, and wood failure percentage (WFP). Bonding pressure and type of glue appeared to have a significant influence on the bonding quality of CLT or glulam, with also significant interactions with the kind of species bonded. If a 0.8 N/mm² bonding pressure seemed to provide better results, vacuum-pressed (0.085 N/mm² bonding pressure) mixed poplar-oak CLT or glulam glued with PUR were very close to reaching the requirements of the standards. Generally, CLT or glulam entirely made from oak delaminated more than the mixed specimens. However, their residual shear strength can be comparable or even superior to what was obtained with mixed poplar-oak specimens. As a result, residual shear strength after delamination test may be interesting to consider as an additional criterion to assess glue line integrity of hardwood CLT or glulam products. Mon, 13 Jun 2022 00:00:00 GMT http://hdl.handle.net/10985/21995 2022-06-13T00:00:00Z PURBA, Citra Yanto Ciki CHAPLAIN, Myriam COUREAU, Jean-Luc COLLET, Robert POT, Guillaume The objective of this study is to evaluate the influence of manufacturing parameters on the bonding quality of CLT and glulam made from oak and mixing poplar and oak species. Studied bonding parameters were bonding pressure and glue type. To test the bonding durability, the specimens were subjected to a vacuum pressure cycle followed by drying to the initial weight. The bonding quality was then measured from delamination, residual shear strength, and wood failure percentage (WFP). Bonding pressure and type of glue appeared to have a significant influence on the bonding quality of CLT or glulam, with also significant interactions with the kind of species bonded. If a 0.8 N/mm² bonding pressure seemed to provide better results, vacuum-pressed (0.085 N/mm² bonding pressure) mixed poplar-oak CLT or glulam glued with PUR were very close to reaching the requirements of the standards. Generally, CLT or glulam entirely made from oak delaminated more than the mixed specimens. However, their residual shear strength can be comparable or even superior to what was obtained with mixed poplar-oak specimens. As a result, residual shear strength after delamination test may be interesting to consider as an additional criterion to assess glue line integrity of hardwood CLT or glulam products.