Strength grading of narrow dimension Norway spruce side boards in the wet state using first axial resonance frequency

Oscarsson, Jan; Olsson, Anders; Johansson, Marie; Enquist, Bertil; Serrano, Erik

doi:10.1179/2042645311y.0000000015

Cited by 4 publications

(4 citation statements)

References 7 publications

(9 reference statements)

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“…Our result went in line with Glos et al (2006) who separated their sample into boards with and without pith: Tensile strength of boards with pith was 21.5 N/mm 2 as compared to 27.6 N/mm 2 , and MOEdyn was 11,500 N/mm 2 as compared to 13,400 N/mm 2 . Previous investigations confirmed the change of timber characteristics in radial direction: for sawn timber of Norway spruce (Brüchert et al 2000;Oscarsson et al 2011) and for small, defect-free specimens of young Douglas-fir (Langum et al 2009). In general, sawn timber quality of Douglas-fir decreased with increasing distance to ground (Knigge 1958;Barrett and Kellogg 1991).…”

Section: Influence Of Radial and Longitudinal Board Position On Wood Qualitysupporting

confidence: 55%

Influence of initial plant density on sawn timber properties for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)

Rais

Poschenrieder

Pretzsch

et al. 2014

Annals of Forest Science

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& Context Mechanical wood properties are increasingly relevant for structural applications and are influenced by growing space availability. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) has an increasing market share in Europe and is mainly processed to sawn timber. & Aim A sample of 164 thinning trees was taken from two Douglas-fir long-term forestry research plots in Germany. The end-use quality of about 2,000 side and center boards was analyzed as a function of initial plant density (1,000, 2,000, and 4,000 trees per hectare) and log position within the stem. & Methods Sawn timber quality was described by knottiness, density, modulus of elasticity, and strength. Explanatory parameters were radial position, longitudinal position, and initial plant density. All boards were strength graded visually and by the grading machine GoldenEye-706 using both X-rays for detecting densities and size as well as position of knots and laser interferometry for detecting eigenfrequency (DIN 4074, DIN 2012; EN 14081-2, CEN 2010). & Results High plant density led to better mechanical sawn timber quality. Significant differences were especially observed between 1,000 and 2,000 trees per hectare. The yield of machine strength-graded center boards of strength class C24 increased from 50 to 89 % at low and high initial plant density, respectively. & Conclusion Foresters are able to improve end-product quality by controlling planting density in particular. The roundwood price that foresters get should be based on the proportion of higher strength classes within logs to give incentives for a more quality-oriented forest management.

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Section: Influence Of Radial and Longitudinal Board Position On Wood Qualitysupporting

confidence: 55%

Influence of initial plant density on sawn timber properties for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)

Rais

Poschenrieder

Pretzsch

et al. 2014

Annals of Forest Science

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“…However, side boards cut far from the pith as here has been found to have higher E-modulus and strength in many studies, e.g. Oscarsson et al [9] One might argue that a too high rolling shear modulus was assumed for the edgewise gamma evaluation, but it would require a value of Gr=44 MPa to get the edgewise net Emodulus Enet,be to 13.6 GPa, which is not likely. A third possible explanation would be a systematically higher E-modulus of the middle lamella (#3) compared to the outer lamellas (#1 and #5).…”

Section: Detailed Evaluation and Net Section Analysismentioning

confidence: 74%

Bending Properties of 100 Narrow CLT-Based Boards - Static and Dynamic Tests and Dic Analysis

Perstorper,

Vessby,

Lockner

2023

World Conference on Timber Engineering (WCTE 2023)

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Production of CLT-panels typically results in 5-10% cut-offs due to window and door openings. CLTboards can be made by slicing these cut-offs and finger-jointing them. This paper presents bending properties of 100 narrow CLT-boards (45x95x1800) made from 5-ply CLT panels made of Norway spruce. A limited variation in Emodulus (CV=9%) and bending strength (CV=20%) was found with gross section values not far from typical structural C24-timber. The tests indicate that narrow CLT-boards have sufficient bending properties for being used as structural components, also where the bending capacity is formally utilized. However, the variation was slightly higher than for typical tests on larger CLT-elements (CV=8-16%), probably due to the smaller homogenization effect when fewer subparts carry the load. The rolling shear modulus was estimated to be Gr= 65 MPa, which is to be expected due to the distance from the pith of the cross layer boards. The surprisingly high net flatwise bending strength (fm,05=49 MPa) can likely be attributed, for the most part, to the reinforcing effect from the cross layers that limit the slope of grain cracking near knots in the longitudinal layers. DIC-tests revealed an indication of a non-plane normal strain distribution over the beam depth in the shear-free zone between the inner loading points. This might lead to an underestimation of the shearfree local E-modulus according to EN 408.

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“…A commercial handheld stiffness grading device (model: MTG-820), developed by Brookhuis (Enschede, The Netherlands) and TNO (Delft, The Netherlands), was used for testing the average MOE of each lumber piece. This device recorded the stress wave speed and attenuation in each piece to receive the signal in terms of the natural frequency of the lumber under longitudinal vibration [ 23 , 24 , 25 ], which can be used to calculate the MOE (Equation (1)), as follows:

where ρ = density (kg/m 3 ), n = mode number, l = length (mm), and f n = n th natural frequency under longitudinal vibration (Hz). This method was used for the on-site sorting of the lumber in this research program.…”

Section: Methodsmentioning

confidence: 99%

“…A commercial handheld stiffness grading device (model: MTG-820), developed by Brookhuis (Enschede, The Netherlands) and TNO (Delft, The Netherlands), was used for testing the average MOE of each lumber piece. This device recorded the stress wave speed and attenuation in each piece to receive the signal in terms of the natural frequency of the lumber under longitudinal vibration [23][24][25], which can be used to calculate the MOE (Equation (1)), as follows:…”

Section: Modulus Of Elasticity (Moe)mentioning

confidence: 99%

Evaluation of Major Physical and Mechanical Properties of Trembling Aspen Lumber

Wang,

Zhang,

Gong

et al. 2024

Materials

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Trembling aspen (Populus tremuloides) is one of the major species within Populus, a predominant genus of hardwoods in North America. However, its utilization has been limited to pulp and paper or wood-based composite boards. This study aimed at evaluating the major physical and mechanical properties of trembling aspen lumber, with an ultimate objective of using this species to produce engineered wood products (EWPs). The testing materials consisted of 2 × 4 (38 mm × 89 mm) trembling aspen lumber pieces in lengths of 8, 10, and 12 feet (2.44, 3.05, and 3.66 m) with two visual grades, select structural (SS) and No. 2. Machine Stress-Rated (MSR), and longitudinal stress wave (LSW), edgewise third-point bending (EWB), and axial tension tests were conducted on the lumber. It was found that, (1) by increasing the maximum knot size by a half-inch from one-quarter inch, the minimum modulus of elasticity (MOE) measured using the MSR, the mean, and the fifth-percentile ultimate tensile strength (UTS) decreased by about 8.8%, 20.1%, and 29.8%, respectively. (2) Approximately 44% of the trembling aspen lumber met the 1450f-1.3E grade for MSR lumber, and 62% qualified for the 1200f-1.2E grade. (3) There was a great potential for manufacturing cross-laminated timber (CLT) of grade E3, with a rejection rate of about 29%. (4) The mean UTS and MOE values of the SS-grade trembling aspen lumber were 22.88 MPa and 9519 MPa, respectively, being 25.5% and 11.3% lower than that of Spruce–Pine–Fir (S-P-F) lumber. The fifth-percentile UTS and MOE values were 11.57 MPa and 7404 MPa, respectively, marking a decrease of 13.3% and 1.5% compared to the S-P-F lumber. (5) The oven-dried specific gravity (SG) of the trembling aspen wood was 0.40, which was about 3.5% larger than the value provided in the Wood Handbook.

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Strength grading of narrow dimension Norway spruce side boards in the wet state using first axial resonance frequency

Cited by 4 publications

References 7 publications

Influence of initial plant density on sawn timber properties for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)

Influence of initial plant density on sawn timber properties for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)

Bending Properties of 100 Narrow CLT-Based Boards - Static and Dynamic Tests and Dic Analysis

Evaluation of Major Physical and Mechanical Properties of Trembling Aspen Lumber

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