Comparison of three systems for automatic grain angle determination on European hardwood for construction use

Schlotzhauer, Philipp; Wilhelms, Fritz; Lux, Christian; Bollmus, Susanne

doi:10.1007/s00107-018-1286-z

Cited by 20 publications

(21 citation statements)

References 21 publications

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“…This shows it is possible to make a reliable measurement of the fiber orientation on all the species tested. This latter result is different from that of [13], who did not find satisfactory results for oak (Quercus spp. L.).…”

Section: Discussioncontrasting

confidence: 97%

“…Nevertheless, only [5] suggested there is a relationship between ellipse shape and the measurement accuracy of ellipse angle. Moreover, there is no wide comparison of the tracheid effect between species, except in [13] concluding that a split laser with a wavelength of 660 nm and power of 100 mW do not provide satisfactory results on oak (Quercus spp. L.).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussioncontrasting

confidence: 97%

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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“…Prospects of developing the use of hardwood are highlighted in other countries than France. A German National Forest Inventory carried out in 2015 showed that German forests were stocked with approximately 54% coniferous species and 43% hardwood species and that areas with hardwood forests had increased with more than 7% from 2002 to 2012 (Schlotzhauer et al 2018). This trend is also expected to continue, since new silvicultural approaches in Europe will imply an increase of biodiversity through the creation of mixed forest stands.…”

Section: Introductionmentioning

confidence: 99%

Performance of strength grading methods based on fibre orientation and axial resonance frequency applied to Norway spruce (Picea abies L.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and European oak (Quercus petraea (Matt.) Liebl./Quercus robur L.)

Olsson

Pot

Viguier

et al. 2018

Annals of Forest Science

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Performance of strength grading methods based on fibre orientation and axial resonance frequency applied to Norway spruce (Picea abies L.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and European oak (Quercus petraea (Matt.) Liebl./Quercus robur L.)Abstract & Key message Machine strength grading of sawn timber is an important value adding process for the sawmilling industry. By utilizing data of local fibre orientation on timber surfaces, obtained from laser scanning, more accurate prediction of bending strength can be obtained compared to if only axial vibratory measurements are performed. However, the degree of improvement depends on wood species and on board dimensions. It is shown that a model based on a combination of fibre orientation scanning and axial vibratory measurement is very effective for Norway spruce (Picea abies L.) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco). For European oak (Quercus petraea (Matt.) Liebl./Quercus robur L.) boards of narrow dimensions, axial vibratory measurements are ineffective whereas satisfactory results are achieved using a model based on fibre orientation. & Context Machine strength grading of sawn timber is an important value adding process for the sawmilling industry. & Aims The purpose of this paper has been to compare the accuracy of several indicating properties (IPs) to bending strength when applied to Norway spruce (Picea abies L.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and European oak (Quercus petraea (Matt.) Liebl./Quercus robur L.). & Methods The IPs were determined for a set of data comprising scanned high-resolution information of fibre orientation on board surfaces, axial resonance frequency, mass and board dimensions. & Results Whereas dynamic axial modulus of elasticity (MoE) gave good prediction of bending strength of Norway spruce (R 2 = 0.58) and Douglas fir (R 2 = 0.47), it did not for narrow dimension boards of oak (R 2 = 0.22). An IP based on fibre orientation gave, however, good prediction of bending strength for all three species and an IP considering both dynamic axial MoE and local fibre orientation for prediction of bending strength gave very good accuracy for all species (Norway spruce R 2 = 0.72, Douglas fir R 2 = 0.62, oak R 2 = 0.59). Comparisons of results also showed that scanning of fibre orientation on all four sides of boards resulted in more accurate grading compared to when only the two wide faces were scanned.

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“…Although no local, namely cell-related, slope of grain data were sampled, it can be deduced from the results shown below that the local slope of grain should be an efficient indicating property for the variation in MOE and, hence, the tensile strength along the board length. The very promising potential of the local MOE prediction based on slope of grain, although denied by Schlotzhauer et al (2018) for oak, has recently been revealed by Olsson et al (2018) for narrow (100 mm) oak laminations, and will be investigated in a further study. Table 2 displays the statistical evaluation of the measured global and local densities, adjusted to MC = 12%.…”

Section: Slope Of Grainmentioning

confidence: 99%

Variation and serial correlation of modulus of elasticity between and within European oak boards (Quercus robur and Q. petraea)

Tapia

Aicher

2019

Holzforschung

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This research aimed at describing the tensile modulus of elasticity (MOE), density and knot variability between and within oak (Quercus robur, Q. petraea) boards, which is essential for the stochastic modeling of wooden composites, such as glulam. Longitudinal deformations for 100-mm long cells were measured. The local density variation along boards revealed a very low mean coefficient of variation (COV) of 3%. The global MOE was precisely predicted from local (cell) MOEs, which span from 2.6 to 22 GPa. The mean COV of local MOE along board length was 12%, with extremes of 3% and 28%. The cell-related relationships of MOE with either density or knot area ratio showed low R-values of 0.4 and 0.3, respectively. A multivariate linear regression with both variables increased the MOE prediction to R = 0.6, which is below the literature results for beech and spruce wood. A serial correlation analysis of the local MOE was performed for board segments quasi-free of knots and for all cells, investigating different normalization approaches. Applying no MOE normalization delivered too high correlations due to pronounced inter-board MOE variations. A normalization based on an averaged maximum MOE per board delivered reasonable serial correlation results for the first four lags of the MOE knot-free variation (0.61; 0.38; 0.19 and 0.08). Considering also the knot-affected cells reduced the serial correlation roughly by a factor of 2.

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Comparison of three systems for automatic grain angle determination on European hardwood for construction use

Cited by 20 publications

References 21 publications

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

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

Performance of strength grading methods based on fibre orientation and axial resonance frequency applied to Norway spruce (Picea abies L.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and European oak (Quercus petraea (Matt.) Liebl./Quercus robur L.)

Variation and serial correlation of modulus of elasticity between and within European oak boards (Quercus robur and Q. petraea)

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