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Improving strength grading of timber by grain angle measurement and mechanical modeling
Open accessAbstract
Timber strength grading has become a major issue in the European Union during the last years, due to the introduction of the Eurocode 5 and all its related standards. Currently, the most performing strength grading machines are able to locally detect the boards’ knots sizes and positions and interpret this information through adapted grading models. The best lead to improve their accuracy seems to be the introduction of new information about the boards and adapt the mechanical model to take them in account. Small grain angle causes high reduction of clear wood's mechanical properties; local value of slope of grain appears to be of high interest. The aim of this study is to quantify the additional accuracy that grain angle information can bring to an optical scanner used as a strength grading machine. A specific grading model has been developed accordingly, and the results obtained for different machine/model/loading combinations are presented. These results show that slope of grain measurement can significantly improve the accuracy of the optical scanner, for both modulus of elasticity and modulus of rupture estimations.
Overview
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Written from the paper’s full text.
TL;DR
This study quantifies whether local grain angle measurement can improve optical-scanner strength grading of timber, using a new mechanical grading model. Across 1,373 European spruce boards, adding slope-of-grain information improved MOE and MOR predictions, especially for the optical scanner used alone.
Key findings
- For CombiScan+ alone, adding grain angle improved MOR prediction R² by 13 points in bending (48% to 61%) and 9 points in tension (65% to 74%); MOE improved by 9 points in bending (65% to 74%) and 7 points in tension (73% to 80%).
- For CombiScan+ combined with E-Scan, MOE R² remained 87% in bending and 91% in tension, while MOR improved from 62% to 63% in bending and from 73% to 78% in tension when using θ.
- Projection angle φ generally brought more accuracy than diving angle ψ; for CombiScan+ alone in bending, MOR R² was 60% for φ, 55% for ψ, and 61% for θ.
- The linear grain-angle variation assumption produced an average error about 2° above scanner measurement accuracy and constant through board thickness; induced MOE/MOR error was above scanner repeatability but below grading error.
Methods
- Sample: 1,373 European spruce (*Picea abies*) boards, 4 m long, dried to about 12% moisture content; 1,017 were destructively tested in bending and 356 in tension according to EN 408 and EN 384.
- Data acquisition: X-ray densitometry with CombiScan+ for local density and KDR; E-Scan vibration analysis for dynamic MOE; laser tracheid-effect measurement of grain angle φ and ψ on top and bottom faces, combined into θ, with 10 mm x-resolution and 3 mm y-resolution.
- Modeling/analysis: an equivalent homogeneous profile reduced local thickness for knots and grain angle via the Hankinson formula; MOE and MOR indicating properties were compared with destructive results by R² across machine/model/loading combinations; error from the linear grain-angle hypothesis was tested on 11 planed boards, and repeatability on 63 boards.
Limitations
- Stated: high timber variability means the numerical results cannot be guaranteed on another batch; the batch contained low- and high-quality timber, stretching the data cloud and giving better coefficients of determination.
- Stated: main limitations are grain-angle measurement accuracy, especially for the fibers’ diving angle, and modeling fiber angle across board thickness; linear variation was acceptable but could be improved.
- Evident from the text: several model parameters and percentiles were chosen to optimize R² on this batch (e.g., n = 1.5, k = 0.05, E_min = 3600 MPa, N = 12 for bending and N = 3 for tension), and the study is limited to European spruce and specific Luxscan machines.
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Claims the paper makes
18 Own interpretation · 15 Own result · 7 No basis given · 3 Sources not found · 2 Not checked yet · 1 Supported so far · 1 No full text of the sources · 1 Own method
The sources with a verdict support this claim; the rest weren’t checked yet, have no full text we could read, or their verdicts aren’t rated yet.
In the paper
“Several studies have already shown that mean grain angle is correlated to boards' mechanical properties (Pope et al., 2005;Brännström et al., 2008).”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 1.2 Strength grading technologies
What the sources say
- Not checked — no full text of the sourcecites Pope et al., 2005 source
- Supportedcites Brännström et al., 2008 source
The Board Strength Predictive Models section states that mean grain angle is correlated with board strength, though only vaguely. Strength is a mechanical property, so the cited study supports the claim, with the qualification that the observed correlation was weak. (LLM, conf=0.90)
boostedcorrelational- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“These results show that slope of grain measurement can significantly improve the accuracy of the optical scanner, for both MOE and MOR estimations.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > Abstract
plaindirect- Asserted: passes — The authors put it forward as true.
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- The authors state this as an assumption: The method is based on the equivalence of the mechanical properties between the computed profiles and the actual boards.
- The authors state this as an assumption: The profile's tensile strength is proportional to its MOE indicating property.
- The authors state this as an assumption: The bending momentum applied on the profile to determine its mechanical behavior is constant.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The top part of Figure 6 shows the high correlation between the product of actual density of the boards by their thickness and the mean of the logarithm of greyscale calculated on the X-Ray images.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.2 Density measurements
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For the MOE prediction the improvement is a little lower: 9 and 7 points respectively in bending and tension.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.3 Strength grading
plaindirect- Asserted: passes — The authors put it forward as true.
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- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“X represents either elasticity modulus or strength, several combinations for the parameters n and k within the range provided by the literature has been tested and the one that gives the best results in terms of coefficient of determination is when n = 1,5 and k = 0,05.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.3.1 Profile's local thickness T(x,y)
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The consideration of the slope of grain improves the coefficient of determination by 13 points for the model with the CombiScan+ used alone for the MOR prediction in bending;”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.2 Density measurements
plaindirectn = 3- Asserted: passes — The authors put it forward as true.
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- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“E min is the threshold of modulus of elasticity when KDR is equal to 1 and on this batch the result of its optimization is 3600 MPa.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.3.2 Profile's mechanical properties
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In the paper
“Baño et al. (2011) also showed that the association of slope of grain and nodosity measurements in a finite element model, conducts to a high correlation between experimental and predicted bending strength (R 2 =0.88).”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 1.2 Strength grading technologies
What the sources say
- Not matchedcites Baño et al. (2011)
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
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In the paper
“However, the number of tested boards, native to various countries across Europe, is in accordance with EN 14081 (AFNOR, 2011) which contains standards requirements for grading machines certification.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
What the sources say
- Not matchedcites AFNOR, 2011
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
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- Not matched
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The results of this study show that grain angle measurement, associated to the grading model presented above, can significantly improve the optical scanner's performances as a strength grading machine.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 5 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The linear regression hypothesis can consequently be considered reasonable in clear wood areas.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.4 Error induced by the grain angle linear variation hypothesis on the prediction of MOE and MOR
plain- Asserted: passes — The authors put it forward as true.
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- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Due to the equation 6 and 8, this uncertainty is highly prejudicial around 0°, i.e. in clear wood areas.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
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In the paper
“This can be explained by the fact that, contrary to the elastic modulus of a beam, the strength depends on the local mechanical properties near the area of the initial fracture.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
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- Rests on an assumption: Strength depends on the local mechanical properties near the area of the initial fracture.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Nevertheless, the grain angle measurement should still permit an improvement for grading timber.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
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A claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“Consequently, the measure of the projection angle (φ) can be obtained thanks to a Principal Component Analysis applied on the ellipse binarized image (Simonaho et al., 2004;Nyström, 2003).”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.2.3 Grain angle
What the sources say
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None of the sources cited for this claim have been checked yet.
In the paper
“According to the method used for the modulus's measure, several studies showed that the coefficients of determination between MOE and MOR are limited to 0.70 (Hanhijärvi et al., 2005;Rohanovà et al., 2011).”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 1.2 Strength grading technologies
What the sources say
- Not checked — no full text of the sourcecites Hanhijärvi et al., 2005
- Not matchedcites Rohanovà et al., 2011
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
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- It may state two separate claims as one. 18
- The quote only partly states this claim. 3
- Probably not a substantial claim. 14
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The study of the grain angle variation between the top and bottom faces reveals that the measured error in terms of grain angle is the same order of magnitude as the scanner's degree of repeatability, although around 2° above.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
plaincorrelational- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For the MOE prediction the improvement is a little lower: 9 and 7 points respectively in bending and tension.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.3 Strength grading
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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The quote only partly states this claim.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The gain observed is always positive but seems to decrease for the higher classes; this observation is more noticeable for the prediction of MOE.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.3 Strength grading
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Its influence on the whole board grading, thus including knotty areas, shows that the error induced on MOE and MOR estimation is clearly above the scanner's repeatability level, but remains under its grading error.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
boosteddirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The coefficient of variation expressed in percent showed us that for both bending and tension tests the variability is higher for the MOR.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.1 Destructive tests
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one. The quote only partly states this claim.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“the improvement is 9 points in tension.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.3 Strength grading
plaindirect- Asserted: passes — The authors put it forward as true.
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The quote only partly states this claim.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This error is on average 2° higher than the measurement accuracy and remains constant through the board's thickness.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.4 Error induced by the grain angle linear variation hypothesis on the prediction of MOE and MOR
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“For the CombiScan+ combined with E-Scan the improvement is visible only on the MOR because the prediction made by the E-Scan is the best.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.3 Strength grading
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Defining these percentiles was a way to obtain another slight increase on coefficient of determination.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.3.3 Indicating properties determination
plaindirect- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Its 99% confidence interval has been measured to less than 5%, which is equivalent to the accuracy of an on-the-run weighing system.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.2.1 X-Ray densitometry
plain- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The fact that the MOR error due to this hypothesis increases with the board's thickness, whereas MOE error does not seem to confirms this hypothesis.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
boosteddirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Note that nearly the same results are obtained if instead of those percentile values, the mean of the 20 smallest values is taken (out of more than 400 values on one board).”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.3.3 Indicating properties determination
plainSingle case- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“It also appears that the projection angle brings more accuracy than the diving angle, despite the fact that, theoretically, both are of the same mechanical importance.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
hedgeddirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Considering their inner fibers direction close to 90°, their mechanical properties along the board's axis are indeed very low.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.3.1 Profile's local thickness T(x,y)
plaindirect- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper may give no reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“We saw that a linear variation model is acceptable, but could also be improved.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 5 Conclusions
hedged- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The main limitations on this field are the accuracy of the grain angle measurement, especially concerning the fibers diving angle, and the modeling of fibers angle across the board's thickness.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 5 Conclusions
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Concerning the comparison between grading performances with and without taking in account the slope of grain, it is clear that this information allows improvement of the optical scanner's prediction accuracy for both MOE and MOR, in tension as well as in bending.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
boosteddirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Furthermore, the fact that the gain seems higher for lower class may be explained by their hypothetical higher nodosity and consequently the deviation of the grain angle around these knots.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
hedgedconditional- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
None of the sources cited for this claim have been checked yet.
In the paper
“The optical scanner's grain angle measurement device produced by Luxscan Technologies and integrated in the CombiScan+ uses the so-called tracheid effect (Simonaho et al., 2004;Nyström, 2003;Hu et al., 2004), which consists in projecting a dot laser perpendicularly on the top and bottom faces.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.2.3 Grain angle
What the sources say
plain- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The fact that the angle estimation error remains stable regardless the position on Z axis can indicate two possibilities: either the 12° error corresponds to the scanner's repeatability for this particular batch, or the validity of the linear variation hypothesis does not depend on the z position, and can therefore be extended on thicker boards.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
hedgedconditional- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The consideration of the slope of grain appears to be effective, but finite element method is not industrially applicable because of the computational time.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 1.2 Strength grading technologies
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“An improvement in the grain angle modeling would likely reduce the MOR error, but would have a fewer importance in the MOE estimation.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The reason is probably that the projection angle measurement comes directly from laser light ellipses orientation, whereas diving angle is estimated from less accurate ellipses patterns statistics.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“It is important to note here that the scanner's repeatability test has been performed on another batch of spruce boards.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Besides, it seems that estimation of the latter is dependent on the surface roughness, which induces additional uncertainty on the estimation of the spheroid eccentricity e 0 .”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
None of the sources cited for this claim could be matched to a paper in Crossref, so there is nothing to check it against.
In the paper
“These destructive tests have been performed according to both EN 408 (AFNOR, 2012) andEN 384 (AFNOR, 2010).”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.1 Samples description and destructive tests
What the sources say
- Not matchedcites EN 408 (AFNOR, 2012)
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Not matchedcites EN 384 (AFNOR, 2010)
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
- Not matched
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“These results consequently highlight a stable and reproducible tendency.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
plain- Asserted: passes — The authors put it forward as true.
- Checkable: fails — It may be too vague to check against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may be too vague to check against evidence.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In other words, a single error in the estimation of slope of grain can greatly change the prediction of MOR, but will have a little effect on the MOE.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Adding the slope of grain information to the combination of the E-Scan & CombiScan+ does not permit a high improvement but this combination seems viable if both of MOE and MOR predictions are decisive for the strength grading due to the highest accuracy that can be obtained on these two parameters.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- The authors state this as an assumption: Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Due to the high variability of timber in terms of mechanical properties, the numerical values of the results presented above cannot be guaranteed on another batch of boards.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 4 Discussions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The ratio between σ p and MOE IP depends on nodosity and grain angle of each board.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.3.2 Profile's mechanical properties
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: fails — The paper may give no reason why it holds.
Probably not a substantial claim. The paper may give no reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The board's rupture is reached when the weakest cross-section is subject to its maximum bending momentum (M b (x)).”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 2.3.3 Indicating properties determination
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: fails — The paper may give no reason why it holds.
Probably not a substantial claim. The paper may give no reason why it holds.
The authors state this as an assumption.
The grey levels of X-ray images are proportional to the acquired corresponding light intensities.
“Assuming that the grey levels of thereby provided images are proportional to the acquired corresponding light intensities, they can be easily and accurately converted into local densities maps.”
The authors state this as an assumption.
Knots density is constant and proportional to the clear wood density.
“For each board, it was assumed that knots density (ρ KN ) is constant and proportional to ρ CW (Oh et al., 2009).”
The authors state this as an assumption.
Wood presents orthotropic light diffusion properties.
“In order to be able to calculate this angle, it was assumed that wood presents orthotropic light diffusion properties, similarly to (Simonaho and Silvennoinen, 2004;Kienle et al., 2008).”
The authors state this as an assumption.
The diving angle is more often equal to 0 due to the extraction way of the board from the trunk.
“The assumption made here is that the diving angle is more often equal to 0 due to the extraction way of the board from the trunk.”
The authors state this as an assumption.
The method is based on the equivalence of the mechanical properties between the computed profiles and the actual boards.
“This method is then based on the equivalence of the mechanical properties between the computed profiles and the actual boards.”
The authors state this as an assumption.
The profile's tensile strength is proportional to its MOE indicating property.
“The profile's tensile strength (σ p ), used in the estimation of the board MOR, is assumed to be proportional to its MOE IP.”
The authors state this as an assumption.
The bending momentum applied on the profile to determine its mechanical behavior is constant.
“In addition, due to the possibility of a strength optimization of boards by cross-cutting and finger jointing, the bending momentum applied on the profile to determine its mechanical behavior is assumed to be constant.”
The paper relies on this without support.
The ellipses contain an indication of the diving angle ψ, which is linked to their shape factor.
“In addition to the projection angle (φ), the ellipses also contain an indication of the diving angle (ψ), which appears to be linked to their shape factor.”
The paper relies on this without support.
Timber presents a very high variability degree due to growth conditions and local singularities.
“As a result, wood presents a very high variability degree due to the growth conditions, and to the presence of local singularities which have a direct influence on boards' mechanical properties.”
The paper relies on this without support.
Statistical characterization of timber is impossible within a single species, a single growth area, and even a single tree.
“This makes a statistical characterization of timber impossible within a single species, a single growth area, and even a single tree.”
The paper relies on this without support.
The first strength grading technology remains limited due to its incapacity to take local singularities into account.
“However, this technology remains limited due to its incapacity to take local singularities in account.”
The paper relies on this without support.
These machines' performances rely mostly on the species mechanical properties correlations, and are not suitable for boards optimization applications.
“In addition, these machines' performances rely mostly on the species mechanical properties correlations, and are not suitable for boards optimization applications.”
The paper relies on this without support.
The grain angle measuring device can only operate on wood surface, specifically on the top and bottom faces of the board.
“As mentioned earlier, the grain angle measuring device can only operate on wood surface, and more precisely on top and bottom faces of the board.”
The authors state this as an assumption.
Grain angle varies linearly between two corresponding points on the top and bottom faces of the board.
“An approximation has consequently been used, which considers that grain angle varies linearly between two corresponding points on top and bottom faces.”
The paper relies on this without support.
Adding grain angle measurement to the CombiScan+ is cheaper than buying an E-Scan.
“Furthermore, adding the grain angle measurement to the Combiscan + is cheaper than buying an E-Scan.”
The paper relies on this without support.
The impact of grain angle on full boards strength grading had not been quantified.
“Yet, its impact on full boards strength grading had not been quantified.”
The paper relies on this without support.
Angles above 25° correspond to knotty areas where grain angle measurement is highly uncertain.
“these angles correspond to knots areas where grain angle measurement is highly uncertain”
The paper relies on this without support.
Strength depends on the local mechanical properties near the area of the initial fracture.
“the strength depends on the local mechanical properties near the area of the initial fracture.”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > 3.2 Density measurements
“For each combination of grading machine, three cases have been studied: θ = 0, θ = φ, θ = ψ and θ estimated from φ and ψ.”
§ Improving strength grading of timber by grain angle measurement and mechanical modeling > FIGURES LEGENDS
“| | 0 | 65% | 48% | 73% | 65% | | CombiScan+ | φ ψ | 73% 70% | 60% 55% | 78% 77% | 71% 71% | | | θ | 74% | 61% | 80% | 74% |”
Citations
Cites
Wood handbook: wood as an engineering material
Ross, R. (2010) · doi:10.2737/fpl-gtr-190 · Cited by 2,596
Automatic measurement of fiber orientation in softwoods by using the tracheid effect
Nyström, J. (2003) · Computers and Electronics in Agriculture · doi:10.1016/s0168-1699(03)00045-0 · Cited by 86
Determination of wood grain direction from laser light scattering pattern
Simonaho, S.-P., Palviainen, J., Tolonen, Y., & Silvennoinen, R. V. J. (2002) · Optics and Lasers in Engineering · doi:10.1016/s0143-8166(02)00144-6 · Cited by 77
Light propagation in dry and wet softwood
Kienle, A., D’Andrea, C., Foschum, F., Taroni, P., & Pifferi, A. (2008) · Optics Express · doi:10.1364/oe.16.009895 · Cited by 77
Baño, V., Arriaga, F., Soilán, A., & Fernández, M. G. (2011) · Biosystems Engineering · doi:10.1016/j.biosystemseng.2011.05.008 · Cited by 73
(2005) · Cited by 32
Hu, C., Tanaka, C., & Ohtani, T. (2004) · Journal of Wood Science · doi:10.1007/s10086-003-0569-z · Cited by 23
Quantification of knots in dimension lumber using a single-pass X-ray radiation
Oh, J.-K., Shim, K.-B., Kim, K.-M., et al. (2009) · Journal of Wood Science · doi:10.1007/s10086-009-1031-7 · Cited by 22
The effect of global slope of grain on the bending strength of scaffold boards
Pope, D. J., Marcroft, J. P., & Whale, L. R. J. (2005) · Holz als Roh- und Werkstoff · doi:10.1007/s00107-005-0010-y · Cited by 19
Roblot, G., Coudegnat, D., Bléron, L., et al. (2008) · Annals of Forest Science · doi:10.1051/forest:2008071 · Cited by 19
Self-citation
Research works printed but not linked: 2
- Brancheriau, L. (2002) Expertise mécanique des sciages par analyse des vibrations dans le domaine acoustique [Dynamic analysis of sawing wood for strength grading], PhD thesis, Univ. Aix Marseille II, France, 278 p.
- Hanhijärvi A., 2005, Report of the Combigrade Project Phase 1, 568
Cited by
Sorted by citations
Lukacevic, M., Kandler, G., Hu, M., Olsson, A., & Füssl, J. (2019) · Materials & Design · doi:10.1016/j.matdes.2019.107617 · Cited by 75
“Thus, in the last years, new and more accurate methods for machine strength grading that utilize the knowledge of fiber directions on board surfaces were developed [7, 8, 9] and even implemented into real-time grading processes [10].”
Olsson, A., & Oscarsson, J. (2016) · European Journal of Wood and Wood Products · doi:10.1007/s00107-016-1102-6 · Cited by 57
“Another group, based in France and involving several universities and institutes, has suggested grading on the basis of X-ray in combination with fibre orientation information from tracheid effect scanning, for example Viguier et al. (2015).”
BackgroundDerikvand, M., Kotlarewski, N., Lee, M., et al. (2019) · Construction and Building Materials · doi:10.1016/j.conbuildmat.2019.03.305 · Cited by 56
Viguier, J., Bourreau, D., Bocquet, J.-F., Pot, G., Bléron, L., & Lanvin, J.-D. (2017) · European Journal of Wood and Wood Products · doi:10.1007/s00107-016-1149-4 · Cited by 47
“The grain angle also explains the reduction of wood strength (Brannstrom et al., 2008; Bano et al., 2011; Olsson et al., 2013; Viguier et al., 2015), in particular the deviation of the bres around knots, which is the result of simultaneous secondary growth of the trunk and branch.”
BackgroundSelf-citationPurba, C. Y. C., Pot, G., Viguier, J., et al. (2019) · European Journal of Wood and Wood Products · doi:10.1007/s00107-019-01400-3 · Cited by 43
Self-citation
Metadata
- Authors
- Viguier, J., Jehl, A., Collet, R., Bleron, L., & Meriaudeau, F.
- Affiliations
- Laboratoire d'Etudes et de Recherche sur le Matériau Bois (FR)
- ParisTech (FR)
- Corresponding author
- Viguier, Joffrey
- Venue
- Wood Material Science & Engineering
- Publisher
- Informa UK Limited
- Published
- 2014-09-22
- Volume
- 10
- Issue
- 1
- Pages
- 145-156
- ISSN
- 1748-0272 (ISSN-L)
- 1748-0280
- OpenAlex
- W2028215163
- Cited by
- 38
- References
- 12
- Citations by year
- 2026: 3 · 2025: 2 · 2024: 3 · 2023: 1 · 2022: 1 · 2021: 5 · 2020: 3 · 2019: 7 · 2018: 4 · 2017: 4 · 2016: 3 · 2015: 2
- FWCI
- 4.42
- Type
- journal article
- Language
- en
- Open access
- green
- hal.science
- Locations
- Wood Material Science and Engineering (publishedVersion)
- HAL (Le Centre pour la Communication Scientifique Directe) (submittedVersion)
- Funders
- Agence Nationale de la Recherche (ANR-12-LABX-ARBRE-01, ANR-12)
- Fonds National de la Recherche Luxembourg
- Topics
- Physical Sciences › Engineering › Building and Construction › Wood Treatment and Properties
- Physical Sciences › Engineering › Industrial and Manufacturing Engineering › Industrial Vision Systems and Defect Detection
- Physical Sciences › Engineering › Mechanical Engineering › Non-Destructive Testing Techniques
- Keywords
- timber strength grading, grain angle, optical scanner, grading model, elastic modulus, flexural strength, knots, Eurocode 5, clear wood, mechanical modeling
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-10-16, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
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