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Wood is one of the oldest widely used building materials. There is an increasing demand for its use in different areas for different purposes. In order to meet this demand, wood-based structural composites have been developed. In this study, some physical and mechanical properties of laminated composite samples obtained from beech (Fagus orientalis Lipsky) wood, which were heat treated and reinforced with carbon and glass fiber using phenol formaldehyde (FF) glue, were investigated. For this purpose, heat treatment was applied to wood materials at 150, 175 and 200°C for 3 hours and test samples were prepared. Density (D), modulus of elasticity in bending (MOE), bending strength, (MOR) compressive strength parallel to grains (CS//) and bonding strength parallel to grains (SS) were determined for the test samples. The test results showed that the bending strength (MOR) and modulus of elasticity in bending (MOE) values of the reinforced samples with carbon and glass fiber increased. However, while it caused significant changes in the compressive strength parallel to the grain (CS//) values depending on the applied heat treatment temperature and the type of reinforcing material, decreases in the bonding strength parallel to the grain (SS) values were determined. In general, the MOR and MOE values of the reinforced test samples with carbon fiber were higher than the reinforced samples with glass fiber, while the CS// and SS values were lower. [ABSTRACT FROM AUTHOR]

In this study, crushing and energy absorption behavior of carbon nanotube (CNT) reinforced glass fiber/epoxy (GFRP) and carbon fiber/epoxy (CFRP) composite tubular structures has been investigated. The study consists of two main parts. First part deals with the experimental studies. At this stage, functionalized multi-walled CNT added (at weight percentages of 0.1; 0.2; 0.3; 0.5; 1; 2%) and additive free GFRP composite plates were produced using hand lay-up method and tension, compression and shear tests were carried out to determine mechanical properties of the composite materials. As a result of these investigations, 0.5% CNT addition is determined to be most suitable rate for the composite in terms of tension, compression, and shear strength. The second part deals with the numerical studies. At this stage, quasistatic crushing and energy absorption characteristics of circular and square cross-section GFRP and CFRP tubes were investigated numerically using the determined mechanical properties in a commercial finite element based software (ABAQUS). The mechanical properties of CFRP tubes were taken from the existing literature. As a result of numerical studies, the specific energy absorption capacity of circular CFRP tubes was found to be most efficient compared to the other tubes. [ABSTRACT FROM AUTHOR]

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