Highly Mechanical Performance of Laminated Veneer Lumber Induced by High Voltage Electrostatic Field

The high voltage electrostatic field (HVEF), as a novel technology, was applied in the study to obtain a highly mechanical performance of LVL (laminated veneer lumber) by increasing limiting value of shear failure strength directly affected by bonding strength. The surface property of wood, polymerization extent of PF, bonding interface of wood-to-PF and mechanical properties of LVL were investigated under the HVEF treatment. The results showed that increased free radicals and total surface energy were acquired under the HVEF treatment resulting from more polar groups (?OH, ?CHO) and ions were triggered leading to decreased contact angles identified both for Poplar and Masson specimens. The HVEF provided more reactions among wood-to-UF and more cross linking reaction of PF occurred in the treating step. The tendency of vertical density profile was more extremely steep than the control with max density increased by 24.93% and 30.24% for Poplar and Masson LVL respectively since adhesive aggregated continuously and orderly along bonding interface and permeation depth reduced to around 200 ?m, accounting for improved bonding shear strength, which eventually brought an enhancement on mechanical properties of LVL with horizon shear strength (?and?), modulus of elasticity and static bending strength significantly enhanced by 14.65%, 10.68%, 20.67% and 12.34% for Poplar LVL and that of Masson LVL enhanced by 17.30%, 13.93%, 18.55% and 12.72%. Besides, the delamination ratio was decreased by 49.57% and 58.32% respectively both for Poplar and Masson specimens.

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Comparison of Bonding Performance Between Plywood and Laminated Veneer Lumber Induced by High Voltage Electrostatic Field.

MATEC Web of Conferences ◽

10.1051/matecconf/201927501013 ◽

2019 ◽

Vol 275 ◽

pp. 01013

Author(s):

Qian He ◽

Tianyi Zhan ◽

Haiyang Zhang ◽

Zehui Ju ◽

Lu Hong ◽

...

Keyword(s):

Mechanical Properties ◽

High Voltage ◽

Electrostatic Field ◽

Wood Surface ◽

Bonding Strength ◽

Surface Characteristics ◽

Wood Failure ◽

Photoelectron Spectra ◽

Masson Pine ◽

Laminated Veneer Lumber

High voltage electrostatic field (HVEF) was applied in order to improve wood surface characteristics, bonding and mechanical properties of wood composites. Masson pine (Pinus massoniana Lamp.) plywood and laminated veneer lumber (LVL) were selected in this study. Surface characteristics were conducted by the electron spin resonance (ESR) and X-ray photoelectron spectra (XPS). Bonding interphase and mechanical properties were investigated by fluorescence microscopy and vertical density profile (VDP), bonding strength, wood failure ratio, MOE and MOR. The results indicated that more increments were obtained in free radicals, O/C ratios and C2-C4 components. This is because electrons broke more wood chemical groups and new ions occurred among wood surface under HVEF. Significantly decreased PF adhesive penetration depth (PD) and increased density at bonding interphase was achieved in HVEF treated composites. More decrease of PD and increment of density were observed in plywood than that of LVL. This was attributed to cross linked wood fibers among bonding interphase in plywood. Mechanical properties of bonding strength, wood failure ratio, MOE and MOR were significantly increased under HVEF treatment both for two composites. Higher bonding strength, MOE and MOR were obtained in plywood and their increments were as 98.53%, 33.33%, 18.55% and 12.72%.

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Engineered Wood Composite of Laminated Veneer Lumber: Physical and Mechanical Properties

Materials Science Forum ◽

10.4028/www.scientific.net/msf.842.103 ◽

2016 ◽

Vol 842 ◽

pp. 103-128

Author(s):

Kang Chiang Liew ◽

Singan Grace

Keyword(s):

Mechanical Properties ◽

Shear Strength ◽

Moisture Content ◽

Bending Strength ◽

Physical And Mechanical Properties ◽

P Value ◽

Thickness Swelling ◽

Laminated Veneer Lumber ◽

Physical Testing ◽

Acacia Hybrid

Utilisation of forest plantation species such as Acacia hybrid has been used in wood-based industry as an alternative to solid wood that was usually attained from natural forest. While, the under-utilised species such as Mangifera sp. is not often been used as raw material for wood products, in this study, laminated veneer lumber (LVL) has been produced from Acacia hybrid and Mangifera sp. The physical and mechanical properties of LVL were determined and compared. For physical testing, the range value of moisture content was 9.41% to 14.56%, Density was 487.90 kg/m3 to 699.10 kg/m3, thickness swelling was between 0.20% to 6.05%, water absorption between 32.71% to 91.25%, and rate of delamination from 0% to 100%. Mangifera sp. LVL has higher moisture content, rate of delamination, and water absorbency. In mechanical testing, it is been found that Acacia hybrid LVL has overall higher strength compared to Mangifera sp. LVL, in terms of static bending strength (MOR and MOE), shear strength, and compression strength. Range of value for MOR was between 10.27 N/mm2 to 129.99 N/mm2, MOE between 1138 N/mm2 to 16472.93 N/mm2, shear strength between 0.43 N/mm2 to 3.40 N/mm2, and compression between 139.45 N/mm2 to 6749.74 N/mm2. For physical testing, the overall result of p-value for moisture content, water absorption, and delamination were significant at p ≤ 0.05, while density and thickness swelling were not significant at p ≥ 0.05. For overall result, the p-value for static bending strength (MOR and MOE) was significant at p ≤ 0.05 while for shear strength and compression strength were not significant at p ≥ 0.05.

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Effect of Submicron Glass Fiber Modification on Mechanical Properties of Short Carbon Fiber Reinforced Polymer Composite with Different Fiber Length

Journal of Composites Science ◽

10.3390/jcs4010005 ◽

2020 ◽

Vol 4 (1) ◽

pp. 5

Author(s):

Nhan Thi Thanh Nguyen ◽

Obunai Kiyotaka ◽

Okubo Kazuya ◽

Fujii Toru ◽

Shibata Ou ◽

...

Keyword(s):

Mechanical Properties ◽

Carbon Fiber ◽

Glass Fiber ◽

Fiber Length ◽

Bending Strength ◽

Mechanical Performance ◽

Volume Fraction ◽

Fiber Concentration ◽

Static Tests ◽

The Impact

In this research, three kinds of carbon fiber (CF) with lengths of 1, 3, and 25 mm were prepared for processing composite. The effect of submicron glass fiber addition (sGF) on mechanical properties of composites with different CF lengths was investigated and compared throughout static tests (i.e., bending, tensile, and impact), as well as the tension-tension fatigue test. The strengths of composites increased with the increase of CF length. However, there was a significant improvement when the fiber length changed from 1 to 3 mm. The mechanical performance of 3 and 25 mm was almost the same when having an equal volume fraction, except for the impact resistance. Comparing the static strengths when varying the sGF content, an improvement of bending strength was confirmed when sGF was added into 1 mm composite due to toughened matrix. However, when longer fiber was used and fiber concentration was high, mechanical properties of composite were almost dependent on the CF. Therefore, the modification effect of matrix due to sGF addition disappeared. In contrast to the static strengths, the fatigue durability of composites increased proportionally to the content of glass fiber in the matrix, regardless to CF length.

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Fabrication and Mechanical Properties of Glass Fiber/Epoxy Nanocomposites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.505-507.37 ◽

2006 ◽

Vol 505-507 ◽

pp. 37-42 ◽

Cited By ~ 2

Author(s):

Jia Lin Tsai ◽

Jui Ching Kuo ◽

Shin Ming Hsu

Keyword(s):

Mechanical Properties ◽

Shear Stress ◽

Shear Strength ◽

Glass Fiber ◽

Shear Failure ◽

Epoxy Nanocomposites ◽

Plane Shear ◽

Epoxy Nanocomposite ◽

Transverse Normal Stress ◽

Mechanical Mixer

This research is aimed to fabricate glass fiber/epoxy nanocomposites containing organoclay as well as to understand the organoclay effect on the in-plane shear strength of the nanocomposites. To demonstrate the organoclay effect, three different loadings of organoclay, were dispersed in the epoxy resin using mechanical mixer followed by sonication. The corresponding glass/epoxy nanocomposites were prepared by impregnating the organoclay epoxy mixture into the dry glass fiber through a vacuum hand lay-up process. Off-axis block glass/epoxy nanocomposites were tested in compression to produce in-plane shear failure. It is noted only the specimens showing in-plane shear failure mode were concerned in this study. Through coordinate transformation law, the uniaxial failure stresses were then converted to a plot of shear stress versus transverse normal stress from which the in-plane shear strength was obtained. Experimental results showed that the fiber/epoxy nanocomposite exhibit higher in-plane shear strength than the conventional composites. This increased property could be ascribed to the enhanced fiber/matrix adhesion promoted by the organoclay.

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EFFECT OF STEREOCOMPLEX FORMATION IN D-LACTIDE-CONTAINING PLLA ON THERMAL BEHAVIORS AND MECHANICAL PROPERTY CHANGES USING THE AGEING DEGRADATION TEST

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s1016237213400036 ◽

2013 ◽

Vol 25 (05) ◽

pp. 1340003

Author(s):

Tsai-Chin Shih ◽

Che-Tong Lin ◽

Sheng-Yang Lee ◽

Wei-Jen Chang ◽

Nai-Chia Teng ◽

...

Keyword(s):

Mechanical Properties ◽

Bending Strength ◽

Mechanical Performance ◽

Test Method ◽

Molar Ratio ◽

Thermal Behaviors ◽

Binding Strength ◽

Stereocomplex Formation ◽

Degradation Test ◽

Hydrolytic Resistance

Introduction: The formation of a stereocomplex between PLLA and PDLA has been studied intensively because it increases the mechanical performance and thermal/hydrolytic resistance of polylactide-based materials; however, few studies have investigated the stereocomplex formation between PLLA and the (D-lactide)-containing PLLA copolymer. To investigate the effect of the D-lactide content of PLLA on the thermal behaviors and mechanical properties, (5D/95L) polylactide [(5D/95L)PLA], which contains a molar ratio of 5% of the D-form and 95% of the L-form of the monomer, and (15D/85L) polylactide [(15D/85L)PLA], which contains a molar ratio of 15% of the D-form and 85% of the L-form of the monomer, were used in a series of specimens. For the hydrolytic degradation test, the specimens were placed in 20-mL vials, which were filled with phosphate-buffered solution; the vials were allowed to stand at 57°C for 91 days in accordance with the ASTM F1635-95 (2000) standard test method for in vitro studies. The mechanical properties, thermal properties and crystallization behaviors were investigated using DSC and MTS, respectively. Results: The initial bending strength of the (5D/95L)PLA and (15D/85L)PLA were 35.4 and 31.1 N, respectively. After 1 week, the binding strength of the (5D/95L)PLA increased by 9.8%, and the binding strength of the (15D/85L)PLA decreased by 26%. In addition, the DSC curve of the (5D/95L)PLA demonstrated a higher melting temperature in the 1st week, and this Tc was observed in the DSC curve of the (5D/95L)PLA only during this time. The DSC curve of the (15D/85L)PLA was irregular. Discussion & Conclusions: In the (5D/95L)PLA, the recrystallization that occurred during the hydrolysis process was confirmed by the Tc and the increase in the bending strength. The stereocomplex crystallites may be formed in the (15D/85L)PLA during the degradation process. Because of the increase in the D-form monomer, the stereocomplexes were generated more easily and acted as nucleation sites. The PLLA crystal near the stereocomplex crystallites exhibited an incomplete structure, which led to a faster decrease in the bending strength. The low D-lactide content in the matrix of the PLLA did not form a stereocomplex crystallite because the surface area was not large enough to act as a nucleation site. However, the higher D-lactide-containing fraction formed a large stereocomplex crystallite. The (5D/95L)PLA demonstrated better thermal/hydrolytic resistance and mechanical stability than the (15D/85L)PLA.

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The impact of fibre processing on the mechanical properties of epoxy matrix composites and wood-based particleboard reinforced with hemp (Cannabis sativa L.) fibre

Journal of Materials Science ◽

10.1007/s10853-021-06629-z ◽

2022 ◽

Author(s):

Albert Hernandez-Estrada ◽

Jörg Müssig ◽

Mark Hughes

Keyword(s):

Mechanical Properties ◽

Fracture Zone ◽

Structural Integrity ◽

Bending Strength ◽

Cannabis Sativa ◽

Mechanical Performance ◽

Epoxy Composites ◽

Fibre Reinforcement ◽

Fibre Bundles ◽

The Impact

AbstractThis work investigated the impact that the processing of hemp (C. sativa L.) fibre has on the mechanical properties of unidirectional fibre-reinforced epoxy resin composites loaded in axial tension, and particleboard reinforced with aligned fibre bundles applied to one surface of the panel. For this purpose, mechanically processed (decorticated) and un-processed hemp fibre bundles, obtained from retted and un-retted hemp stems, were utilised. The results clearly show the impact of fibre reinforcement in both materials. Epoxy composites reinforced with processed hemp exhibited 3.3 times greater tensile strength when compared to the un-reinforced polymer, while for the particleboards, the bending strength obtained in those reinforced with processed hemp was 1.7 times greater than the un-reinforced particleboards. Moreover, whether the fibre bundles were processed or un-processed also affected the mechanical performance, especially in the epoxy composites. For example, the un-processed fibre-reinforced epoxy composites exhibited 49% greater work of fracture than the composites reinforced with processed hemp. In the wood-based particleboards, however, the difference was not significant. Additionally, observations of the fracture zone of the specimens showed different failure characteristics depending on whether the composites were reinforced with processed or un-processed hemp. Both epoxy composites and wood-based particleboards reinforced with un-processed hemp exhibited fibre reinforcement apparently able to retain structural integrity after the composite’s failure. On the other hand, when processed hemp was used as reinforcement, fibre bundles showed a clear cut across the specimen, with the fibre-reinforcement mainly failing at the composite's fracture zone.

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Mechanical Properties of Laminated Veneer Lumber Beams Strengthened with CFRP Sheets

Archives of Civil Engineering ◽

10.2478/ace-2019-0018 ◽

2019 ◽

Vol 65 (2) ◽

pp. 57-66 ◽

Cited By ~ 1

Author(s):

M. Bakalarz ◽

P. G. Kossakowski

Keyword(s):

Mechanical Properties ◽

Cross Section ◽

Bending Strength ◽

Carbon Fabric ◽

Static Work ◽

Work Analysis ◽

Cfrp Sheets ◽

Laminated Veneer Lumber ◽

Frp Reinforcement ◽

Bottom Face

AbstractThis paper presents the results of the static work analysis of laminated veneer lumber (LVL) beams strengthened with carbon fabric sheets (CFRP). Tested specimens were 45mm wide, 100 mm high, and 1700 mm long. Two types of strengthening arrangements were assumed as follows: 1. One layer of sheet bonded to the bottom face; 2. U-shape half-wrapped reinforcement; both sides wrapped to half of the height of the cross-section. The reinforcement ratios were 0.22% and 0.72%, respectively. In both cases, the FRP reinforcement was bonded along the entire span of the element by means of epoxy resin. The reinforcement of the elements resulted in an increase in the bending strength by 30% and 35%, respectively, as well as an increase in the global modulus of elasticity in bending greater than 20% for both configurations (in comparison to the reference elements).

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Study on the Static Performance of Prefabricated UHPC-Steel Epoxy Bonding Interface

Advances in Civil Engineering ◽

10.1155/2021/6663517 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Yang Zou ◽

Jinlong Jiang ◽

Zhixiang Zhou ◽

Xifeng Wang ◽

Jincen Guo

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Shear Strength ◽

Shear Test ◽

Interfacial Shear Strength ◽

Interfacial Shear ◽

Bonding Interface ◽

Tensile Shear ◽

Epoxy Bonding ◽

Shear Coupling

Prefabricated UHPC-steel composite structure can make full use of the two materials’ mechanical and construction performance characteristics, with super mechanical properties and durability, which has been proved to be a very promising structure. However, using traditional mechanical connectors to connect prefabricated UHPC and steel not only is inconvenient for the prefabrication of UHPC components but also introduces heavy welding work, which is detrimental to the construction speed and antifatigue performance of the composite structure. Bonding UHPC-steel interface with epoxy adhesive is a potential alternative to avoid the above problem. In order to explore the mechanical properties of the prefabricated UHPC-steel epoxy bonding interface, this study carried out the direct shear test, tensile test, and tensile-shear test of the UHPC-steel epoxy-bonded interface (prefabricated UHPC-steel epoxy bonding interface). The results show that the interface failure is mainly manifested as the peeling of the epoxy-UHPC interface and the destruction of part of the UHPC matrix (the failure of the UHPC's surface). In pure shear and pure tension state, the interfacial shear strength is 5.14 MPa and the interfacial tensile strength is 1.18 MPa. In the tensile-shear state, the interfacial shear strength is 0.61 MPa and the interfacial tensile strength is 1.06 MPa. The stress-displacement curves of the interface normal and tangential direction are all in the shape of a two-fold line. The ultimate displacement was within 0.1 mm, showing the characteristics of brittle failure. Finally, a numerical model of the tensile specimen is established based on the cohesive interface element, and the interfacial tensile-shear coupling failure mechanism (tensile-shear coupling effect) is analyzed.

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Method of Optimisation for Ambient Temperature Cured Sustainable Geopolymers for 3D Printing Construction Applications

Materials ◽

10.3390/ma12060902 ◽

2019 ◽

Vol 12 (6) ◽

pp. 902 ◽

Cited By ~ 20

Author(s):

Shin Bong ◽

Behzad Nematollahi ◽

Ali Nazari ◽

Ming Xia ◽

Jay Sanjayan

Keyword(s):

Mechanical Properties ◽

3D Printing ◽

Ambient Temperature ◽

Shear Failure ◽

Mechanical Performance ◽

Silicate Solution ◽

Ambient Temperatures ◽

Tension Tests ◽

Shape Retention ◽

Interlayer Bond

Since the initial introduction of geopolymers, these materials have been characterised as environmentally-friendly sustainable substitutes for ordinary Portland cement (OPC). There is a routine increase in the application of geopolymers, especially in advanced technologies. Because of its better rheological characteristics compared to OPC, geopolymers are appropriate materials for extrusion-based 3D printing technologies. This paper focuses on the optimisation of an ambient temperature cured geopolymer for 3D printing construction applications. The effects of mixture parameters, including the type of hydroxide solution (HS), the type of silicate solution (SS) and the mass ratio of SS to HS on the workability, extrudability, shape retention ability and mechanical performance of different geopolymer mixtures were investigated. Accordingly, an optimum mixture was identified for geopolymers cured at ambient temperatures. Mechanical properties of the optimised mixture, including flexural and compressive strengths, were measured in different directions with respect to the printed layers. Further, uniaxial tension tests were also conducted on the optimised mixture to measure its interlayer bond strength. The results showed that among the activators investigated, the sodium-based activator composed of sodium hydroxide and sodium silicate solutions, with a SiO2/Na2O ratio of 3.22, was the most effective activator, providing appropriate workability and extrudability, along with reasonable strength and a high shape retention ability. The acquired mechanical properties exhibited anisotropic behaviour in different testing direction. The strength of the interlayer bond was found to be adequate to avoid interfacial shear failure.

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The mechanical performance of the laminated aluminum-epoxy/glass fiber composites containing halloysite nanotubes: An experimental investigation

Journal of Industrial Textiles ◽

10.1177/1528083720960735 ◽

2020 ◽

pp. 152808372096073

Author(s):

Marwa A Abd El-baky ◽

Mohamed A Attia

Keyword(s):

Mechanical Properties ◽

Shear Strength ◽

Tensile Strain ◽

Mechanical Performance ◽

Flexural Modulus ◽

Halloysite Nanotubes ◽

Interlaminar Shear Strength ◽

Plane Shear ◽

Bearing Strength ◽

Interlaminar Shear

In this study, the effect of different weight percentages (wt. %) of halloysite nanotubes (HNTs) on the mechanical performance of glass laminate aluminum (Al) reinforced epoxy (GLARE) was investigated. GLARE (3/2) laminates with quasi-isotropic lay-up, [Al/[(0°/90°)/(45°/−45°)]s/Al/[(0°/90°)/(45°/−45°)]s/Al] filled with 0, 0.25, 0.5, 1, 2 and 3 wt. % of HNTs were fabricated using hand lay-up followed by compression molding. To explore the effect of HNTs on the mechanical properties, tensile, flexural, in-plane shear, interlaminar shear, bearing and impact tests were conducted. Results demonstrated that the inclusion of 1 wt. % of HNTs into GLARE leads to maximum improvements of 35.67, 8.50, 28.85, 50.47, 50.27, 30.43, 23.73, 72.08, 30.74, and 51.52% in tensile strength, tensile strain, Young's modulus, modulus of toughness, flexural strength, flexural strain, in-plane shear strength, interlaminar shear strength, bearing strength, and impact strength, respectively, compared to pristine GLARE. An enhancement of 38.89% in the flexural modulus was attained by adding 0.5 wt. % of HNTs to GLARE compared to pristine GLARE. The tensile strength, tensile strain, modulus of toughness, flexural strength, flexural modulus, flexural strain, in-plane shear strength, and interlaminar shear strength of GLARE filled with 3 wt. % of HNTs are 0.91, 0.88, 0.91, 0.91, 0.71, 0.83, 0.85, and 0.91 times those of the original GLARE. But Young’s modulus, bearing strength, and impact strength are 1.10, 1.15 and 1.20 times those of the original GLARE. To investigate the fracture mechanism, field emission scanning electron microscope (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) were used. The microscopic images revealed that adding HNTs lead to the improvement in the interaction between the epoxy matrix and glass fiber, thereby improving the mechanical properties.

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