Enhancement of bending strength properties of two wood species reinforced with two types of carbon fibre fabrics and two layouts

In Estonia, hardwoods form approximately 50% of all forest area, where the main species are birch (30%), gray alder (9%), aspen (6%) and black alder (4%). Birch has been extensively used by the veneer-based industry, but species like black alder, gray alder and aspen have not been commonly used by the veneer-based products industry due to the lower quality of this resource. The aim of this research is to determine the effect of different lay-up schemes and usages of gray alder, black alder and aspen on the mechanical properties of plywood, by replacing birch veneer in the plywood core with alternative wood species. The main veneer and plywood characteristics will be evaluated according to the current standards, e.g., veneer strength perpendicular to grain, plywood bonding and bending strength, and modulus of elasticity. All processing parameters will be kept similar to those used generally by birch plywood manufacturers. The results showed that birch and black alder plywood panels had generally the highest bending strength properties, followed by grey alder and aspen. It was also found that, for proper gluing, birch veneers had the lowest glue consumption, 152 g/m2, and aspen had the highest glue consumption, 179 g/m2. It was found that when lower density wood was used in the plywood, the product density increased. Low density wood veneers had higher glue consumption, and also higher compaction in thickness than birch veneers under the same pressure. Overall, it was shown that the wood species used in this study have slightly lower strength properties, but with proper lay-up schemes, these wood species could be successfully used by the veneer-based products industry.

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Density, hardness and strength properties of densified fir and aspen woods pretreated with water repellents

Holzforschung ◽

10.1515/hf-2020-0075 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Hüseyin Pelit ◽

Fatih Emiroglu

Keyword(s):

Compression Ratio ◽

Bending Strength ◽

Linseed Oil ◽

Vacuum Treatment ◽

Strength Properties ◽

Aspen Wood ◽

Positive Effect ◽

Water Repellents ◽

Impregnated Wood ◽

Compression Temperature

AbstractIn this study, the effect of thermo-mechanical densification on the density, hardness, compression strength, bending strength (MOR), and modulus of elasticity (MOE) of fir and aspen wood pretreated with water repellents was analyzed. Wood specimens were impregnated with paraffin, linseed oil and styrene after pre-vacuum treatment. Then, the impregnated wood specimens were densified with compression ratios of 20 and 40%, and at 120, 150 and 180 °C. The results indicated that the density, hardness and strength properties of the all densified specimens (untreated and impregnated) increased depending on the compression ratio and temperature. For all tested properties, higher increases were obtained in the paraffin and styrene pretreated specimens compared to untreated samples. However, the increase rates in linseed oil pretreated specimens were generally lower than untreated specimens. Regarding water repellents the most successful results in all tested properties were determined in styrene pretreated specimens. The density, hardness and strength properties of all specimens increased with the increase in compression ratio. On the other hand, the increase in the compression temperature negatively affects the properties of untreated and linseed oil pretreated specimens, while having a generally positive effect on the properties of paraffin pretreated specimens. However, all tested properties of styrene pretreated specimens have increased significantly due to the increase in compression temperature. The increasing strength properties of wood as a result of densification have increased much more with paraffin and especially styrene pretreatment. These combinations can be considered as an important potential for applications that require more hardness and strength.

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Joining of Carbon Fibre Reinforced SiC (Cf/SiC) to Ni-Based Superalloy with Multiple Interlayers

International Journal of Modern Physics B ◽

10.1142/s0217979203019654 ◽

2003 ◽

Vol 17 (08n09) ◽

pp. 1777-1781 ◽

Cited By ~ 17

Author(s):

Shujie Li ◽

Jianjun Zhang ◽

Xiaobo Liang ◽

Huiping Duan ◽

Yan Zhang

Keyword(s):

Carbon Fibre ◽

Dwell Time ◽

Bending Strength ◽

Welding Temperature ◽

Maximum Value ◽

Welding Pressure ◽

Metallic Filler ◽

Microstructural Studies

Welding of C f / SiC to Ni-based superalloy has been realized using Cu/W/Cu/W/Cu multiple interlayers. The bending strength of the joints has been improved by using the active metallic filler contacted with C f / SiC . The strength of the joints is remarkably affected by the welding temperature. The maximum value 102.1 MPa has been obtained at 970°C (dwell time: 10 min., welding pressure: 34.3 MPa). Microstructural studies were also conducted.

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Study on Particleboard made from Nipa palm (Nypa fruticans) stem wood and Rajkoroi (Albizia richardiana) wood

Journal of Non Timber Forest Products ◽

10.54207/bsmps2000-2018-qpjp02 ◽

2018 ◽

Vol 25 (1) ◽

pp. 15-18

Author(s):

Md. Mahabubur Rahaman ◽

◽

Khurshid Akhter ◽

S. Hossain ◽

Md. Rakibul Islam ◽

...

Keyword(s):

Tensile Strength ◽

Dimensional Stability ◽

Bending Strength ◽

Strength Properties ◽

Wood Chips ◽

Standard Specification ◽

Stem Wood ◽

Nypa Fruticans ◽

Albizia Richardiana ◽

Nipa Palm

The study was conducted to find out the suitability of making particleboard using nipa palm (Nypa fruticans) stem wood and rajkoroi (Albizia richardiana) wood chips. Particleboards were fabricated at six different ratios of nipa palm stem and rajkoroi wood chips such as 100:0, 75:25, 50:50, 25:75, 10:90 and 0:100. Characteristics of particleboards such as modulus of rupture, internal bond strength, water absorption, thickness swelling and moisture content were measured. Results shows that particleboards made from 100% rajkoroi wood chips have the highest static bending properties and highest tensile strength properties of other particleboards but 100% nipa palm stem wood chips have the lowest static bending and lowest tensile strength properties of other particleboards. 10% nipa palm stem wood chips particleboard have the highest bending strength and tensile strength is better than 100% nipa palm stem wood chips and other mixing chips of particleboards. Mechanical, water resistance and dimensional stability properties were tested according to Indian standard specification. Tensile strength passed the British and German standard specification and nearest to Bureau of Indian Standard, bending strength was found nearest to Indian Standard but lower than German and British Standard specification. Strength property of rajkoroi wood chips particleboard is higher than nipa palm steam wood chips particleboard but dimensional stability is lower than nipa palm steam wood chips particleboard.

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Machine of testing the ceramic’s bending strength properties at high temperature and ultra-low speed

Frontiers of Mechanical Engineering in China ◽

10.1007/s11465-010-0094-x ◽

2010 ◽

Vol 5 (3) ◽

pp. 289-293

Author(s):

Jianhui Zhang ◽

Onuki Akiyoshi ◽

Fang Ye

Keyword(s):

High Temperature ◽

Bending Strength ◽

Strength Properties ◽

Low Speed

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

Forests ◽

10.3390/f11060644 ◽

2020 ◽

Vol 11 (6) ◽

pp. 644 ◽

Cited By ~ 2

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.

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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 ◽

10.3390/f10020189 ◽

2019 ◽

Vol 10 (2) ◽

pp. 189 ◽

Cited By ~ 4

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.

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