scholarly journals Effects of Fiber Angle on the Tensile Properties of Partially Delignified and Densified Wood

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5405
Author(s):  
Matthias Jakob ◽  
Jakob Gaugeler ◽  
Wolfgang Gindl-Altmutter
Keyword(s):  
Tensile Strength ◽  
Tensile Properties ◽  
Mechanical Performance ◽  
Treated Wood ◽  
Untreated Wood ◽  
Mechanical Anisotropy ◽  
Densified Wood ◽  
Wood Fibers ◽  
Transverse Tensile ◽  
Transverse Tensile Strength

Partial delignification and densification provide a pathway to significant improvement in the mechanical performance of wood. In order to elucidate potential effects of this treatment on the mechanical anisotropy of wood, partially delignified and densified spruce wood veneers were characterized at varying degrees of off-axis alignment. While the tensile strength and the modulus of elasticity (MOE) were clearly improved in parallel to the axis of wood fibers, this improvement quickly leveled off at misalignment angles ≥30°. For transverse tensile strength, the performance of alkaline-treated and densified wood was even inferior to that of untreated wood. Microscopic examination revealed the presence of microscopic cracks in treated wood, which are assumed to be responsible for this observation. It is concluded that impaired transverse tensile properties are a weakness of partially delignified and densified wood and should be considered when a potential usage in load-bearing applications is intended.

Experimental reexamination of transverse tensile strength for IM7/8552 tape-laminate composites

2020 ◽  
Vol 54 (23) ◽  
pp. 3297-3312
Author(s):  
Caitlin M Arndt ◽  
Nelson V de Carvalho ◽  
Michael W Czabaj
Keyword(s):  
Tensile Strength ◽  
Weak Link ◽  
Surface Preparation ◽  
Test Method ◽  
Transverse Fracture ◽  
Laminate Composites ◽  
Transverse Tensile ◽  
Specimen Volume ◽  
Transverse Tensile Strength

Due to the observed dependence of transverse-tensile strength, Y T, on test geometry and specimen size, there is no consensus regarding a test method that can uniquely measure Y T. This study reexamines the characterization of Y T by comparing results from established flexure tests with results from a new tensile test that exhibits consistent failure in the gage region. Additionally, the effects of surface preparation and direction of transverse fracture are investigated. Results show that Y T is inversely proportional to specimen volume and surface roughness and is insensitive to direction of transverse fracture. The relationship between specimen volume and Y T is adequately captured by Weibull strength-scaling theory, except at the tails of the Y T distributions. However, specimens exhibited microcracking prior to failure, which violates the “weak-link” assumption of the Weibull theory. These findings highlight the challenges of using deterministic Y T values in progressive damage analysis.

scholarly journals Investigation of Interlaminar Defects and their Influence on Interlaminar Strength

1996 ◽  
Vol 5 (4) ◽  
pp. 096369359600500
Author(s):  
J Ziao ◽  
J Tao
Keyword(s):  
Tensile Strength ◽  
Large Scale ◽  
Peel Strength ◽  
Test Method ◽  
Bending Test ◽  
Four Point Bending ◽  
Transverse Tensile ◽  
Interlaminar Shear ◽  
Transverse Tensile Strength ◽  
Set Up

In this paper, we directed our attention to the interlaminar defects and their influence on the interlaminar strengths. With the aid of a S-570 scanning electron microscope, the morphology and distribution of interlaminar defects were inspected and documented. According to their shape, size and cause of formation, the defects were classified into five types: flakiness void, irregular shaped debond, local imperfectly cured resin, debond in two multi-directional plies, and inhomogeneous fibers and the large scale debond by these fibers. The cause of defects formation was discussed by analyzing the manufacturing process of composites. The influence of defects on the interlaminar strength and its mechanism was analyzed experimentally and theoretically. The results indicate that these defects, with different effects, decrease the interlaminar strength because they form interlaminar cracks, and the interlaminar shear strength is less affected than interlaminar tensile strength, which is measured according to GB4944 test method. To comprehend defects distribution effect, a four-point-bending test method was introduced to measure the interlaminar peel strength, and a discussion was made on the correlation between the interlaminar tensile strength, interlaminar peel strength and in-plane transverse tensile strength. Finally the concept of interlaminar defect coefficient, which can be used to characterize the defects, was set up and the formula to calculate it was proposed.

Effect of Nanocellulose Loading on Tensile Properties of Nitrile Rubber

2017 ◽  
Vol 264 ◽  
pp. 112-115
Author(s):  
Erfan Suryani Abdul Rashid ◽  
Wageeh Abdulhadi Yehye ◽  
Nurhidayatullaili Muhd Julkapli ◽  
Sharifah Bee O.A. Abdul Hamid
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Tensile Strength ◽  
Tensile Test ◽  
Tensile Properties ◽  
Mechanical Performance ◽  
Butadiene Rubber ◽  
Fracture Surfaces ◽  
Scanning Electron

Nanocellulose (NCC) is incorporated into nitrile butadiene rubber (NBR) latex with the composition 0 to 5 phr using dipping method. Mechanical properties of NBR/NCC composites using tensile test was used to characterize their mechanical performance and the fracture surfaces post tensile test were studied. The tensile strength of NBR/NCC composites increase significantly with the addition of nanocellulose. This could be anticipated due to the presence of Van der Waals interaction between hydrophilic natures of nanocellulose with hydrophobic of NBR consequently limits the tearing propagation. The result was supported with the fracture surfaces morphology viewed under Fourier Emission Scanning Electron Microscopy (FESEM).

Fibronectin matrix polymerization increases tensile strength of model tissue

2004 ◽  
Vol 287 (1) ◽  
pp. H46-H53 ◽  
Author(s):  
Candace D. Gildner ◽  
Amy L. Lerner ◽  
Denise C. Hocking
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Actin Cytoskeleton ◽  
Tensile Properties ◽  
Mechanical Performance ◽  
Actin Organization ◽  
Tissue Constructs ◽  
Fibronectin Matrix ◽  
Matrix Polymerization ◽  
Tension Generation

The composition and organization of the extracellular matrix (ECM) contribute to the mechanical properties of tissues. The polymerization of fibronectin into the ECM increases actin organization and regulates the composition of the ECM. In this study, we examined the ability of cell-dependent fibronectin matrix polymerization to affect the tensile properties of an established tissue model. Our data indicate that fibronectin polymerization increases the ultimate strength and toughness, but not the stiffness, of collagen biogels. A fragment of fibronectin that stimulates mechanical tension generation by cells, but is not incorporated into ECM fibrils, did not increase the tensile properties, suggesting that changes in actin organization in the absence of fibronectin fibril formation are not sufficient to increase tensile strength. The actin cytoskeleton was needed to initiate the fibronectin-induced increases in the mechanical properties. However, once fibronectin-treated collagen biogels were fully contracted, the actin cytoskeleton no longer contributed to the tensile strength. These data indicate that fibronectin polymerization plays a significant role in determining the mechanical strength of collagen biogels and suggest a novel mechanism by which fibronectin can be used to enhance the mechanical performance of artificial tissue constructs.

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