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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]

Plastic-based bushings and bearings are used in some parts of the machines used in different sectors of the industry. In applications where high temperature, corrosion, chemical resistance and wear resistance are required, choosing a right material is very important for the service life of the machine element. In this study, the tribological performances of pure poly-ether-ether-ketone (PEEK) polymer and 30% by weight glass fiber (GF) reinforced poly-ether-ether-ketone (PEEK-30GF) composite were investigated. The materials used in the experiments are in the form of rods produced for industrial purposes by the extrusion method. Tribological experiments were carried out 2000 m under dry sliding conditions at room temperature using a pin-on-disc wear test device. Two different loads (30 N and 60 N) and four different speeds (1, 2, 3 and 4 m s-1) were used in the experiments. As a result of the experiments, the friction coefficient, pin temperature and specific wear rate of pure PEEK polymer and 30% glass fiber reinforced PEEK composite were determined. As a result of the experiments, with the increase of the sliding speed, the wear rate of both pure PEEK and glass fiber reinforced PEEK composite increased, while the friction coefficient values decreased. At low load (30 N) and speed (1 m s-1), PEEK composite was found to be 2.46 times more wear resistant than pure PEEK polymer. In addition, microstructure examinations of the wear surface of the test materials were carried out using an optical microscope. Adhesive wear at low loads and speeds and abrasive wear mechanisms at high speeds and loads were observed for both test materials. [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]

Copyright of Turkiye Klinikleri Journal of Dental Sciences is the property of Turkiye Klinikleri and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to find the best wear resistant polymer or polymer composite pair that can be used in electrical contact breaker applications. For this, the pin-on-disc (PoD) wear test machine was used. Poly-etherether- ketone (PEEK) polymer and 20% and 30% by weight glass fiber (GF) reinforced PEEK composites were used as pin material. Long glass fiber reinforced and calcium carbonate mineral-filled unsaturated polyester composite material was used as the counterpart material. In the tribological experiments, while the effect of glass fiber reinforcement on wear was examined, the effect of the applied pressure was also investigated. The highest wear rate was obtained in PEEK+30% GF polymer composite with 4.42x10-14 m2 N-1 under 5.30 MPa pressure, while the lowest wear rate was obtained with 1.13x10-14 m2 N-1 under 1.77 MPa pressure. As a result of the study, it was determined that among the materials subjected to the wear test, the long glass fiber reinforced and calcium carbonate filled pure polyester composite material and the pure PEEK polymer pair were the most suitable pairs for electrical contact breaker applications. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Defense Sciences / Savunma Bilmleri Dergisi is the property of Turkish Military Academy Defense Sciences Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Synthesized phenol formaldehyde and commercial urea formaldehyde were mixed with glass fiber and Ceratoniasiliqua seed particles to produce MDF (Medium density fiberboard). Various reinforcement and matrix ratios were applied and ZnB2O3.3,5H2O was used as additives due to its fire retardant property. By means of mechanical and burning tests produced composites were investigated. Outdoor usage possibility of the composites was checked by swelling thickness and water absorption experiments. Results indicate that glass fiber increase composite strength up to 14,438 kPa, whereas particle reinforcement enhances hardness to 142 VH. Addition of 5% of ZnB2O3.3.5H2O increase LOI value from 39% to %52 oxygen concentration. [ABSTRACT FROM AUTHOR]