Tracheid Effect Scanning and Evaluation of in-Plane and Out-of-Plane Fiber Direction in Norway Spruce Timber

Briggert, Andreas; Hu, Min; Olsson, Anders; Oscarsson, Jan

doi:10.22382/wfs-2018-053

Cited by 20 publications

(18 citation statements)

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“…The orientation of the major axis of the ellipse corresponds to the projection of the longitudinal direction of the fiber. This phenomenon is commonly referred to as the tracheid effect (Nyström 2003;Simonaho et al 2004;Briggert et al 2018). This diffusion varies according to the species, and its physical explanation is not yet fully understood (Nyström 2003;Zhou and Shen 2003;Simonaho et al 2004).…”

Section: Introductionmentioning

confidence: 99%

“…This diffusion varies according to the species, and its physical explanation is not yet fully understood (Nyström 2003;Zhou and Shen 2003;Simonaho et al 2004). The tracheid effect has for many years been used in commercial timber scanners as a mean to detect wood defects such as knots (Nieminen et al 2013;Briggert et al 2018). It has recently been used for machine grading purposes by measuring the fiber direction (Olsson et al 2013;Viguier et al 2015Viguier et al , 2018Ehrhart et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Contactless moisture content measurement on green veneer based on laser light scattering patterns

et al. 2020

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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.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Contactless moisture content measurement on green veneer based on laser light scattering patterns

et al. 2020

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“…In the literature, this phenomenon is called "tracheid effect", because it was mostly developed for softwoods [1,3]. The shape of this scattered light spot can be fitted by the equation of an ellipse with some mathematical algorithm [4][5][6], the orientation of the major axis giving the local fiber orientation in the plane of the considered surface. Indeed, fiber orientation is a 3D phenomenon, but tracheid effect only allows measurement of the projected fiber orientation at the scanned surface [6].…”

Section: Introductionmentioning

confidence: 99%

“…Other ellipse parameters, like axis ratio and area, are less often studied, while they can also characterize the light scattering effect. Nevertheless, [2] used a shape factor of the ellipses to estimate the fiber diving angle (out of the ellipse plane), but this method appears not precise enough [6]. [5] Measured the length of ellipse minor and major axes on Japanese beech (Fagus crenata Blume) and sugi (Cryptomeria japonica D.Don) on sawn and planed wood surfaces, while rotating samples.…”

Section: Introductionmentioning

confidence: 99%

Influence of wood anatomy on fiber orientation measurement obtained by laser scanning on five European species

et al. 2020

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In order to obtain high production rates of sawn timber, the sawmilling industry can use laser scanning, allowing knot detection and machine strength grading. In particular, laser scanners measure grain angle using the so-called tracheid effect on wood surface where an elliptic scattering of the laser light can be observed. This paper aims to describe the light scattering obtained by a laser beam projection on wood surface and to assess the accuracy of such fiber orientation measurement on five European species. Firstly, fiber orientation measurement error was assessed by rotating samples. Secondly, the description of the scattering effect was done considering ellipse axis ratios and areas. This was studied according to several parameters such as wood surface machining, moisture content, and orthotropic planes of symmetry. Fiber orientation measurement was successfully performed on all the tested species. The measurement error was below 1.6°, except for oak longitudinal–radial (LR) plane showing an error up to 3.1°. For most of the species, the error was higher in LR plane because of the influence of medullary rays. Despite the observation of major variabilities in laser light scattering, it was possible to measure the grain angles with a good accuracy for all investigated species.

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“…Many authors proposed finite element models to study the behavior of Norway spruce wood members, e.g. [16][17][18][19]. Rafsanjani et al [20] numerically predicted the swelling of the hierarchical cellular structure of Norway spruce softwood assuming a transverse anisotropic model.…”

Section: Introductionmentioning

confidence: 99%

Inverse Calculation of Timber-CFRP Composite Beams Using Finite Element Analysis

Saad

Lengyel

2020

Period. Polytech. Civil Eng.

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This study focuses on the flexural behavior of timber beams externally reinforced using carbon fiber-reinforced polymers (CFRP). Linear and non-linear finite element analysis were proposed and validated by experimental tests carried out on 44 timber beams to inversely determine the material properties of the timber and the CFRP. All the beams have the same geometrical properties and were loaded under four points bending. In this paper the general commercial software ANSYS was used, and three- and two-dimensional numerical models were evaluated for their ability to describe the behavior of the solid timber beams. The linear elastic orthotropic material model was assumed for the timber beams in the linear range and the 3D nonlinear rate-independent generalized anisotropic Hill potential model was assumed to describe the nonlinear behavior of the material. As for the CFRP, a linear elastic orthotropic material model was introduced for the fibers and a linear elastic isotropic model for the epoxy resin. No mechanical model was introduced to describe the interaction between the timber and the CFRP since failure occurred in the tensile zone of the wood. Simulated and measured load-mid-span deflection responses were compared and the material properties for timber-CFRP were numerically determined.

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Tracheid Effect Scanning and Evaluation of in-Plane and Out-of-Plane Fiber Direction in Norway Spruce Timber

Cited by 20 publications

References 1 publication

Contactless moisture content measurement on green veneer based on laser light scattering patterns

Contactless moisture content measurement on green veneer based on laser light scattering patterns

Influence of wood anatomy on fiber orientation measurement obtained by laser scanning on five European species

Inverse Calculation of Timber-CFRP Composite Beams Using Finite Element Analysis

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