scholarly journals Estimation of the Modulus Fir Wood Reinforced With PBO Fiber Mesh

2018 ◽  
Vol 64 (4) ◽  
pp. 105-121
Author(s):  
P. Sokołowski ◽  
P. G. Kossakowski

AbstractThis paper presents the results of preliminary tests for estimating the modulus of elasticity of wooden beams from firs reinforced with PBO fiber mesh. The tests were carried out in the Materials Strength Laboratory at the Kielce University of Technology in Kielce, Poland with PN-EN 408: 2004. The wooden elements were subjected to a four-point bending test with the aim of estimating the elastic modulus when bending, assuming the loading velocities of the loading forces of 5 mm / min. The obtained results show a significant increase in the load-bearing capacity of beams reinforced with PBO mesh.

2017 ◽  
Vol 27 (4) ◽  
pp. 105-120 ◽  
Author(s):  
Konrad Rodacki

Abstract This article discusses the issue of composite timber-glass I-beams, which are an interesting alternative for load-bearing beams of ceilings and roofs. The reasoning behind the use of timber-glass I-beams is the combination of the best features of both materials - this enables the creation of particularly safe beams with regard to structural stability and post-breakage load capacity. Due to the significant differences between the bonding surfaces of timber and glass, a study on the adhesion of various adhesives to both surfaces is presented at the beginning of the paper. After examination, two adhesives were selected for offering the best performance when used with composite beams. The beams were investigated using a four-point bending test under quasi-static loading.


2019 ◽  
Vol 15 (2) ◽  
pp. 125-133
Author(s):  
Vít Lojda ◽  
Aran van Belkom ◽  
Hana Krejčiříková

AbstractIn ballasted track, the wheel load is transmitted to the subgrade via sleepers commonly made of impregnated wood, prestressed concrete, steel or recently developed polymer sleepers. Mentioned material types of sleepers are characterized by different elastic moduli being a key parameter in any numerical model. Hence, this paper aims to determine the elastic modulus of sleepers subjected to a laboratory four-point bending test. Traffic resembling load level of 60 kN adopted from a typical axle load distributed by the rails to the sleeper was applied in a quasistatic and cyclic loading. The samples included sleepers made of polymers complemented with wood and pre-stressed concrete. The results of this paper are based on the elastic modulus investigation. Main conclusions are focused on the sleeper’s elastic modulus under changing loading frequencies. Wood and prestressed concrete sleepers indicated mainly elastic behaviour resulting in a constant elastic modulus. However, polymer sleepers showed a loading frequency dependent elastic modulus as a result of their viscous elastic behaviour. Moreover, the conclusions of this paper involve E-modulus measurements of impregnated beech sleepers in order to describe their piece by piece elasticity variation due to their natural origin.


2020 ◽  
Vol 309 ◽  
pp. 57-61
Author(s):  
Jakub Řepka ◽  
Tomáš Vlach ◽  
Diana Mariaková ◽  
Zuzana Jirkalová ◽  
Petr Hájek

This paper discusses the feasibility of an innovative anchoring element which is designed to be integrated into the volume of an ultra-thin coffered façade panel made of textile reinforced concrete and to not increase its external dimensions. The first part of the article describes the composition and shape of the façade panel and focuses on the manufacturing of the composite anchoring element made of carbon technical textile penetrated with polymer matrix which is intentionally identical composition as in the case of the façade panel reinforcement. The second part of the article focuses on the behavior of the composite anchoring element and its effect on its surroundings during the mechanical loading of the façade panel. Specimens of the coffered façade panel with integrated anchoring elements were subjected to four-point bending test to determine the impact of the anchoring elements on the façade panel flexural tensile strength and type of failure. Additional specimens were tested to determine the load-bearing capacity of the anchoring elements.


Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Xianzhi Gao ◽  
Guangyan Liu ◽  
Lu Wang ◽  
Yanan Yi ◽  
Guang Lin ◽  
...  

AbstractAs a natural graded material, bamboo has gradually increasing elastic modulus along the radial direction from the inner to the outer skin. Accurate measurement of the modulus distribution plays an important role in bamboo-based structural design. However, it is difficult to characterise this modulus distribution by using conventional testing approaches on bamboo slices. A more effective method was developed in this study for the inverse identification of gradually varying material properties. The method is based on the digital image correlation and finite element model updating techniques. The radial distribution of the elastic modulus of bamboo was obtained through only one four-point bending test. The inversely identified modulus distribution was verified through uniaxial tensile tests on sliced bamboo strips and microscopic observation of the volume fraction distribution of its vascular bundle. The results showed that the elastic modulus of the bamboo material decreased from the outer skin (20 GPa) to the inner skin (2 GPa), which is in good consistence with the tensile test results on sliced specimens.


2021 ◽  
Vol 1144 (1) ◽  
pp. 012039
Author(s):  
M A Iman ◽  
N Mohamad ◽  
A A A Samad ◽  
Steafenie George ◽  
M A Tambichik ◽  
...  

2021 ◽  
pp. 152808372199377
Author(s):  
Jalil Hajrasouliha ◽  
Mohammad Sheikhzadeh

In the interest of reducing the weight and also cost of blade skins, various automatic preform manufacturing processes were developed including tape laying, filament winding and braiding. Among them, the circular braiding process was found to be an efficient method in producing seamless preforms on mandrels with various geometries. In this regard, an attempt was made to produce a carbon fiber reinforced composite with the shape of NACA 23018 airfoil using a circular braiding machine. Thus, suitable wooden mandrels were manufactured using NACA 23018 airfoil coordinates, which were obtained by assuming the perimeter of 20 cm. Furthermore, both biaxially and triaxially braided preforms were produced and subsequently impregnated with epoxy resin through an appropriate fabrication method. To assess their performance, four-point bending test was carried out on samples. Ultimately, the elastic response of braided composite airfoils was predicted using a meso-scale finite element modeling and was validated with experimental results.


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