scholarly journals The Usefulness of Pine Timber (Pinus sylvestris L.) for the Production of Structural Elements. Part II: Strength Properties of Glued Laminated Timber

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4029
Author(s):  
Radosław Mirski ◽  
Dorota Dziurka ◽  
Monika Chuda-Kowalska ◽  
Jakub Kawalerczyk ◽  
Marcin Kuliński ◽  
...  
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Strength Properties ◽  
Bending Test ◽  
Structural Elements ◽  
Pine Wood ◽  
Glued Laminated Timber ◽  
The Individual ◽  
Horizontal Arrangement

The paper assessed the feasibility of manufacturing glued structural elements made of pine wood after grading it mechanically in a horizontal arrangement. It was assumed that the pine wood was not free of defects and that the outer lamellas would also be visually inspected. This would result in only rejecting items with large, rotten knots. Beams of the assumed grades GL32c, GL28c and GL24c were made of the examined pine wood. Our study indicated that the expected modulus of elasticity in bending was largely maintained by the designed beam models but that their strength was connected with the quality of the respective lamellas, rather than with their modulus of elasticity. On average, the bending strength of the beams was 44.6 MPa. The cause of their destruction was the individual technical quality of a given item of timber, which was loosely related to its modulus of elasticity, assessed in a bending test. Although the modulus of elasticity of the manufactured beam types differed quite significantly (11.45–14.08 kN/mm2), the bending strength for all types was similar. Significant differences occurred only during a more detailed analysis because lower classes were characterized by a greater variation of the bending strength. In this case, beams with a strength of 24 MPa to 50 MPa appeared.

scholarly journals The Usefulness of Pine Timber (Pinus sylvestris L.) for the Production of Structural Elements. Part I: Evaluation of the Quality of the Pine Timber in the Bending Test

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3957 ◽  
Author(s):  
Radosław Mirski ◽  
Dorota Dziurka ◽  
Monika Chuda-Kowalska ◽  
Marek Wieruszewski ◽  
Jakub Kawalerczyk ◽  
...  
Keyword(s):  
Pinus Sylvestris ◽  
Cross Sections ◽  
Modulus Of Elasticity ◽  
Physical And Mechanical Properties ◽  
Bending Test ◽  
Structural Elements ◽  
Forest Division ◽  
Pine Lumber ◽  
Round Cross

The study assessed the quality of pine lumber by marking the modulus of elasticity in the horizontal system. The research material was a plank with the following dimensions: 137 mm wide × 39.50 mm thick × 3485 mm long. The pine wood was obtained by sawing timber in the form of logs with round cross sections and originating from the Forest Division Olesno (50°52′30″ N, 18°25′00″ E). Each long log was sawn to provide four logs of about 3.5 m, which were marked as butt-end logs (O), middle logs (S)—2 items, and top logs (W). The origin of the logs from the trunk (Pinus sylvestris L.) has a significant impact on the physical and mechanical properties of the wood from which they are made. Only butt-end logs (log type O) allows for the production of high-quality timber elements. The pine timber that was evaluated in this paper had a high density of about 570 kg/m3 and a high percentage of timber items were assigned to class C24 and higher (above 50%). The adopted horizontal model of evaluation of the modulus of elasticity gave similar results to those obtained in an evaluation according to the EN-408.

Mechanical Grading of Structural Larch Dimension Lumber

2012 ◽  
Vol 517 ◽  
pp. 683-688 ◽  
Author(s):  
Wan Li Lou ◽  
Hai Qing Ren ◽  
Zhao Hui Wang ◽  
Xiu Qin Luo
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Bending Test ◽  
Total Production ◽  
Good Relationship ◽  
Dimension Lumber ◽  
Structural Applications ◽  
Viable Approach

Larch dimension lumber bending strength properties from full-size bending test were used to establish preliminary grade boundary settings for mechanical grading of lumber by modulus of elasticity. Simulated production using the grade boundary settings were evaluated for modulus of rupture, ultimate tensile strength, and ultimate compressive strength. The results showed a good relationship between modulus of rupture and modulus of elasticity, and the observed relationships between strengths properties were consistent with that assumed for the standard grades. Through mechanical grading, larch dimension lumber could be sort grades: M14, M30 and M40. Assuming the visual requirements are met, the M30 and M40 grades account for more than 80% of the total production. Mechanical grading of larch appears to be a viable approach for grading Chinese large for structural applications.

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).

scholarly journals A Comparison of the Loading Direction for Bending Strength with Different Wood Measurement Surfaces Using Near-Infrared Spectroscopy

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 644 ◽  
Author(s):  
Yohei Kurata
Keyword(s):  
Near Infrared ◽  
Bending Strength ◽  
Tensile Force ◽  
Strength Properties ◽  
Bending Test ◽  
Tangential Section ◽  
Compression Force ◽  
Radial Section ◽  
Loading Direction ◽  
Light Acquisition

Wood is widely used throughout society for building resources and paper. To further expand wood’s use in the wood industry, we tested the bending strength properties of wood and certified its internal quality by using near-infrared spectroscopy (NIRS). In this study, the relationship between bending strength and loading direction was compared by changing the light acquisition point of wood surfaces to elucidate the anisotropy of the wood using NIRS. The two loading directions were defined by using a bending test as the radial section and the tangential section. Two light acquisition points with NIRS were also defined by a bending test as the loading position (the compression surface) and the opposite surface (the tensile surface), and a comparison was made between the prediction accuracy of the wood’s mechanical strength properties obtained via a bending test using two pieces of light acquisition data. The strength properties of the wood bending tests were the elastic modulus in bending (Eb), the bending strength (Fb) and density (DEN). Cryptomeria japonica was prepared and cut into a final size of 20 mm × 20 mm × 320 mm. Near-infrared (NIR) spectra were obtained from the compression force side and the tensile force side (calculating these averages), and a partial-least-squares regression (PLSR) was performed for the regression analysis. In the NIR measurement position, the best calibration results of the PLSR were the averaged data between the side undergoing the compression force and that undergoing the tensile force. Comparing the two loading directions, the result for the radial section was slightly superior to that of the tangential section. The radial section showed a good relationship between the spectra acquisition position and the arrangement of the wood’s structure. The estimation accuracy of bending strength properties differed depending on the location where the NIR spectra acquisition was performed.

scholarly journals Influence of Site Conditions and Quality of Birch Wood on Its Properties and Utilization after Heat Treatment. Part I—Elastic and Strength Properties, Relationship to Water and Dimensional Stability

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 189 ◽  
Author(s):  
Vlastimil Borůvka ◽  
Roman Dudík ◽  
Aleš Zeidler ◽  
Tomáš Holeček
Keyword(s):  
Heat Treatment ◽  
Dimensional Stability ◽  
Bending Strength ◽  
Color Change ◽  
Untreated Wood ◽  
Strength Properties ◽  
Treatment Temperature ◽  
Impact Bending ◽  
The Impact

This work deals with the quality of birch (Betula pendula) wood from different sites and the impact of heat treatment on it. Two degrees of heat treatment were used, 170 °C and 190 °C. The resulting property values were compared with reference to untreated wood samples. These values were wood density, compressive strength, modulus of elasticity (MOE), bending strength (MOR), impact bending strength (toughness), hardness, swelling, limit of hygroscopicity, moisture content and color change. It was supposed that an increase in heat-treatment temperature could reduce strength properties and, adversely, lead to better shape and dimensional stability, which was confirmed by experiments. It was also shown that the properties of the wood before treatment affected their condition after heat treatment, and that the characteristic values and variability of birch properties from 4 sites, 8 stems totally, were reflected in the properties of the heat-treated wood. Values of static MOR were the exception, where the quality of the input wood was less significant at a higher temperature, and this was even more significant in impact bending strength, where it manifested at a lower temperature degree. Impact bending strength also proved to be significantly negatively affected by heat treatment, about 48% at 170 °C, and up to 67% at 190 °C. On the contrary, the most positive results were the MOE and hardness increases at 170 °C by about 30% and about 21%, respectively, with a decrease in swelling at 190 °C by about 31%. On the basis of color change and other ascertained properties, there is a possibility that, after suitable heat treatment, birch could replace other woods (e.g., beech) for certain specific purposes, particularly in the furniture industry.

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.

scholarly journals Mechanical performance of wood under artificial and natural weathering treatments

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 6267-6277
Keyword(s):  
Exposure Time ◽  
Modulus Of Elasticity ◽  
Elastic Limit ◽  
Bending Strength ◽  
Mechanical Performance ◽  
General Information ◽  
Bending Test ◽  
Natural Weathering ◽  
Linear Regression Models ◽  
Artificial Weathering

Natural and artificial weathering treatments were studied to determine the change of wood properties as a function of exposure time. This paper aimed to provide general information about the mechanical performance of wood under natural and artificial weathering treatments and define a relationship between them. The eight strength classes of ABNT NBR 7190 (1997) were considered, in addition to a paired sampling approach. The modulus of elasticity and conventional strength value in static bending, strength in compression parallel to the grain, hardness perpendicular to the grain, and the elastic limit in the static bending test were investigated. Linear regression models for mechanical performances under artificial and natural aging treatments of the exposure time were made and tested using an analysis of variance. According to the results, 360 days of natural weathering provoked a change in mechanical performance of 15.72% that included a decrease in strength and modulus of elasticity and an increase in elastic limit. Twelve hours of the artificial weathering treatment provided the effect of 6.22 days of natural weathering exposure.

scholarly journals Properties of Plywood Made from Perforated Veneers

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1709
Author(s):  
Jozef Fekiač ◽  
Jozef Gáborík ◽  
Marek Vojtkuliak
Keyword(s):  
Weight Reduction ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Bending Properties ◽  
Bend Testing ◽  
Bending Radius ◽  
Point Bend ◽  
The Individual

The paper is focused on the bending properties of beech plywood made from veneers with perforations. The modification of the plywood was done by the targeted perforations in veneers used. The perforations were rectangular in shape 5 × 30 mm. There was a gap of 10 mm between the perforations (in each direction) and the perforations in the individual rows were shifted by 10 mm relative to each other. Two structures of lightweight plywood were investigated: sheathed (lightweight type 1) with perforated inner layers sheathed with solid veneer and perforated (lightweight type 2) with perforations in each layer. Bending properties were evaluated by three-point bend testing. The results showed decreased bending strength (MOR) as well as decreased modulus of elasticity in bending (MOE) with reduction of weight. Bending strength (MOR) was reduced by 33 to 57% and modulus of elasticity (MOE) by 13 to 43% compared to standard (non-lightweight) plywood. Bendability of lightweight plywood expressed by the minimum bending radius (Rmin) and the coefficient of bendability (koh) point to a slight decrease in bendability by 1 to 35% compared to standard (non-lightweight) plywood. The benefit of the proposed plywood lightweight constructions is weight reduction by 16.5 to 24.4%.

scholarly journals Behavior of Glulam Beams Strengthened in bending with BFRP Fabrics

2021 ◽  
Vol 31 (2) ◽  
pp. 1-14
Author(s):  
Agnieszka Wdowiak-Postulak ◽  
Grzegorz Świt
Keyword(s):  
Bending Strength ◽  
Load Capacity ◽  
Experimental Studies ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymers ◽  
Structural Elements ◽  
Basalt Fibers ◽  
Reinforced Polymers ◽  
Glued Laminated Timber ◽  
Environmentally Friendly Method

Abstract The article presents results of an experimental studies on reinforcement of pine beams made from glued laminated timber with subsurface basalt fibers (BFRP). An experimental research program was presented, in which the bending strength of glued laminated timber of middle and lower quality class was increased after using BFRP basalt fabrics. Thanks to the use of BFRP reinforcement, an average load capacity increased by 47% and stiffness by 6% in comparison to non-reinforced elements. Based on the research, it was found that the use of BFRP basalt fabrics is an effective method for strengthening damaged wooden elements. Thus, it is an environmentally friendly method of improving the static work of structural elements by combining wood with other natural materials such as basalt fiber reinforced polymers.

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