scholarly journals Efficiency of Visual and Machine Strength Grading of Sawn Timber with Respect to Log Type

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1467
Author(s):  
Izabela Burawska-Kupniewska ◽  
Sławomir Krzosek ◽  
Piotr Mańkowski
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Strength Class ◽  
Limited Extent ◽  
Visual Method ◽  
Medium Quality ◽  
Sawn Timber ◽  
Machine Strength

A batch of pine timber sawn from butt, middle and top logs was strength graded with the visual method (classification into grading classes KW—best quality, KS—medium quality, KG—inferior quality and Reject) and with the machine strength grading method—performed with the use of a mobile timber grader (classification into C strength classes). We compared the efficiency of grading classes and strength classes, depending on the type of log from which the material was obtained (butt, middle, top). Next, a strength grading machine was used to measure the modulus of elasticity in bending (MOE) and static bending strength (MOR). The ANOVA confirmed the influence of both the log type (butt, middle, top), the C strength class, and the visual strength grading class on the values of density (DEN) and MOR. Timber density and MOR decreased from the butt log section to the top log section. The ANOVA confirmed the influence of log type on MOE values, but only to a limited extent.

scholarly journals Quality and Bending Properties of Scots Pine (Pinus Sylvestris L.) Sawn Timber

Forests ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1200
Author(s):  
Izabela Burawska-Kupniewska ◽  
Sławomir Krzosek ◽  
Piotr Mańkowski ◽  
Marek Grześkiewicz
Keyword(s):  
Mechanical Properties ◽  
Scots Pine ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Mechanical Parameters ◽  
Bending Properties ◽  
Characteristic Values ◽  
Sawn Timber ◽  
The Moment

The paper presents the partial research results of a mechanical properties study conducted on Scots pine from the Silesian Forestry Area in Poland. The scope of research included the visual strength grading of the timber according to the PN-D-94021:2013 standard, mechanical testing (according to EN 408:2012) and an attempt to assign visuals to the C strength classes. The EN 1912: 2012 standard assigns the visual sorting classes of individual wood species (according to national sorting standards) to the C strength classes introduced by the EN 338: 2018 standard. At the moment, this standard does not assign Polish visual sorting classes (KW, KS, and KG) to C strength classes. The obtained MOE (modulus of elasticity) and MOR (static bending strength) values were corrected according to the EN 384:2018 standard, and their characteristic values were later calculated. On this basis, we proposed a classification of the grading classes determined on the basis of PN-D-94021 into C classes described in EN 338:2018, which is necessary in the process of the transposition of Polish strength grades (KW, KS, KG, and Reject) and the qualification of them in line with EN 1912:2012. The calculated characteristic values of density, MOR and E0 (the modulus of elasticity parallel to the grain) allowed us to assign Polish visual grades KW, KS, and KG to C35, C30, and C20, respectively. The pine timber under research had high physical and mechanical parameters, which translated into high C classes to which the KW, KS, and KG timber categories were assigned.

scholarly journals Characterization and Structural Performance in Bending of CLT Panels Made from Small-Diameter Logs of Loblolly/Slash Pine

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2436 ◽  
Author(s):  
Vanesa Baño ◽  
Daniel Godoy ◽  
Diego Figueredo ◽  
Abel Vega
Keyword(s):  
Bending Strength ◽  
Strength Class ◽  
Small Diameter ◽  
Slash Pine ◽  
Structural Performance ◽  
Visual Grade ◽  
Cross Laminated Timber ◽  
Thinning Operations ◽  
Sawn Timber ◽  
The Individual

The main objective of this work was to study the structural viability of using small-diameter logs of Uruguayan Loblolly/Slash pine, mainly from thinning operations, to design cross-laminated timber (CLT) panels. A visual grade named “CTH” (coniferous thinning) was proposed, and 45 specimens of sawn timber boards were tested, resulting in 51% lower bending strength than that of the minimum strength class C14. Subsequently, 20 CLT panels were manufactured and experimentally tested, the results showed that the bending strength of the CLT panels was 43% above that of the individual layers. Additionally, the structural performance of the CLT panels for use in floors was calculated, and the thickness-span relationship depending on strength class and imposed load are presented. Results showed than the use of CTH timber to design CLT floors implies a volume (m3/m2) 17% higher than that using C24 timber.

Modulus of elasticity as a criterion for strength grading of structural sawn timber

2019 ◽  
Vol 105 ◽  
pp. 91-97
Author(s):  
SŁAWOMIR KRZOSEK ◽  
IZABELA BURAWSKA-KUPNIEWSKA ◽  
PIOTR MAŃKOWSKI ◽  
MAREK GRZEŚKIEWICZ ◽  
ANDRZEJ MAZUREK
Keyword(s):  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Elasticity Modulus ◽  
Wood Technology ◽  
Static Modulus ◽  
Forest Regions ◽  
Sawn Timber ◽  
Static Modulus Of Elasticity ◽  
Forest District ◽  
Machine Strength

Modulus of elasticity as a criterion for strength grading of structural sawn timber. The paper presents an analysis that was performed on sawn timber originating from the Silesian Forest District in terms of parameters related to the elastic properties of the material. As part of the research, static modulus of elasticity (in accordance with EN 408: 2010 + A1: 2012) and dynamic modulus (using a portable device for machine strength grading) were determined. Both elasticity modulus were correlated with the density of the material, and compared with the database developed on the basis of previous research carried out at Faculty of Wood Technology of WULS- SGGW, including the results of strength grading of sawn timber from five natural Polish forest regions.

scholarly journals Relationships between Thermoplastic Type and Properties of Polymer-Triticale Boards

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1750 ◽  
Author(s):  
Radosław Mirski ◽  
Pavlo Bekhta ◽  
Dorota Dziurka
Keyword(s):  
Mechanical Properties ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Thickness Swelling ◽  
Hydrophobic Properties ◽  
Pine Wood ◽  
Moisture Contents ◽  
The Face

This study examined the effects of selected types of thermoplastics on the physical and mechanical properties of polymer-triticale boards. The investigated thermoplastics differed in their type (polypropylene (PP), polyethylene (PE), polystyrene (PS)), form (granulate, agglomerate) and origin (native, recycled). The resulting five-ply boards contained layers made from different materials (straw or pine wood) and featured different moisture contents (2%, 25%, and 7% for the face, middle, and core layers, respectively). Thermoplastics were added only to two external layers, where they substituted 30% of straw particles. This study demonstrated that, irrespective of their type, thermoplastics added to the face layers most favorably reduced the hydrophobic properties of the boards, i.e., thickness, swelling, and V100, by nearly 20%. The bending strength and modulus of elasticity were about 10% lower in the experimental boards than in the reference ones, but still within the limits set out in standard for P7 boards (20 N/mm2 according to EN 312).

Research on the Bending Properties of the Bamboo-Wood Container Flooring

2013 ◽  
Vol 744 ◽  
pp. 366-369
Author(s):  
Juan Wei ◽  
Dan Zeng ◽  
Ming Jie Guan
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Accelerated Aging ◽  
Modulus Of Rupture ◽  
Bending Properties ◽  
Before And After ◽  
Aging Performance

In this paper, the bending properties of bamboo-wood container flooring and bamboo curtain-OSB container flooring were tested and the six-cycle artificial accelerated aging method of ASTM D1037 was conducted to evaluate the aging performance of two kinds of bamboo-wood container floorings. The modulus of rupture (MOR) and modulus of elasticity (MOE) were tested in the longitudinal and transverse directions before and after aging. The results showed that both the bending strength and MOE decreased after aging. The retention ratios of MOR of the bamboo-wood container flooring and bamboo curtain-OSB container flooring were respectively 43.5%, 72.0%, and the retention ratios of MOE were 54.6%, 76.3%. In general, the effect of aging on the bamboo-wood container flooring was larger than that on the bamboo curtain-OSB container flooring.

Strength Properties of Chestnut Structural Timber with Wane

2013 ◽  
Vol 778 ◽  
pp. 377-384 ◽  
Author(s):  
Michele Brunetti ◽  
Michela Nocetti ◽  
Paolo Burato
Keyword(s):  
Cross Section ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Rectangular Cross Section ◽  
Ring Width ◽  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Mean Value ◽  
National Standards ◽  
Timber Element

Grading of timber for structural purposes allows material with similar physical and mechanical properties to be grouped together. The groups are defined by specific strength values and indicate the basic working stresses and stiffnesses to be used for structural design purposes. In particular, visual strength grading bases the assignment of each timber element to a grade on the characteristics that are visually measurable (i.e. knots, slope of grain, annual ring width). Very similar principles are implemented for the in situ assessment of timber structures, as recommended for example by the Italian standard UNI 11119, that specifies the procedures for the diagnosis of timber members. Currently, however, European standards and most of the national standards on strength grading refer to timber elements with rectangular cross section, while in existing buildings, members with irregular cross section are extremely common. Thus, 10 different provenances (5 from Italy and 5 from France) of chestnut timber were sampled. More than 600 structural elements with wane were visually examined in laboratory and all the characteristics were collected. Bending tests were then performed on each timber element until failure, and bending strength, as well as modulus of elasticity and density, were determined. Here, the limitations for the main strength-reducing characteristics and the characteristic values (fifth percentile for bending strength and density and the mean value for modulus of elasticity) of chestnut timber with wane are presented.

Preparation of polylactic acid composites containing β–Ca(PO3)2 fibers

1999 ◽  
Vol 14 (2) ◽  
pp. 418-424 ◽  
Author(s):  
Toshihiro Kasuga ◽  
Haruhiko Fujikawa ◽  
Yoshihiro Abe
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Methylene Chloride ◽  
High Strength ◽  
High Energy ◽  
Fiber Content ◽  
Bending Test ◽  
Natural Bone ◽  
Naoh Solution ◽  
Very High Energy

Novel biomaterials for application to artificial bone with modulus of elasticity close to that of natural bone were prepared using bioresorbable poly-L-lactic acid (PLLA) and high-strength β–Ca(PO3)2 fibers treated with dilute NaOH solution. PLLA dissolved by using methylene chloride was mixed with the fibers. After drying the mixture, it was hot-pressed uniaxially under a pressure of 40 MPa at 180 °C, resulting in fabrication of a PLLA composite containing β–Ca(PO3)2 fibers. Almost no degradation in the bending strength was observed even when a large amount of the fibers (≈50 wt. %) was introduced, and the modulus of elasticity was increased effectively with increasing the fiber content. The PLLA composite with modulus of elasticity of <5 GPa similar to that of natural bone was found to be prepared when the fiber content was over 35 wt. %. The bending test of the composites showed that very high energy is consumed for their fracture and that the fracture proceeds step by step, even beyond the maximum stress.

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