High-Temperature Effect on the Tensile Mechanical Properties of Unidirectional Carbon Fiber-Reinforced Polymer Plates

Carbon fiber-reinforced polymer (CFRP) has the advantages of a high strength-weight ratio and excellent fatigue resistance and has been widely used in aerospace, automotive, civil infrastructure, and other fields. The properties of CFRP materials under high temperatures are a key design issue. This paper presents the quasi-static tensile mechanical properties of unidirectional CFRP plates at temperatures ranging from 20 to 600 °C experimentally. The laser displacement transducer was adopted to capture the in situ displacement of the tested specimen. The results showed that the tensile strength of the CFRP specimen was affected by the high-temperature effect significantly, which dropped 68% and 16% for the 200 and 600 °C, respectively, compared with that of the room temperature. The degradation measured by the laser transducer system was more intensive compared with previous studies. The elastic modulus decreased to about 29% of the room temperature value at 200 °C. With the evaporation of the resin, the failure modes of the CFRP experienced brittle fracture to pullout of the fiber tow. The study provides accurate tensile performance of the CFRP plate under high-temperature exposure, which is helpful for the engineering application.

Influences of high temperature on mechanical properties of fly ash based geopolymer mortars reinforced with PVA fiber

In this study, a geopolymer composite containing PVA fiber was produced to recycle waste fly ash and obtain an eco-friendly binder. Mechanical properties of geopolymer mortars, produced by using F class fly ash which was activated with NaOH (sodium hydroxide), and reinforced by PVA (polyvinyl alcohol) fiber were investigated after high temperature effect. Geopolymer mortar samples produced by mixing with fly ash, sand, water and NaOH were placed in standard molds of 40×40×160 mm3. PVA fibers were used at percentages of 0,5%, 1% and 1,5% by volume in the experiment. Tests were performed on mortars exposed to high temperatures of 200°C, 400°C, 600°C and 800°C for physical and mechanical properties. For the specimens not subjected to high temperatures, an increase in the compressive strength of mortars containing PVA fibers was observed in comparison to mortar without PVA fiber. On the other hand, it was concluded that losses in compressive strength were less for mortar without PVA fiber when compared with the mortars containing PVA fibers. As a result of the modeling, the PVA ratio, which gives the optimum flexural and compressive strength, was determined as 1,47%. As a result of melting of PVA fibers under the effect of high temperature, 83,58% loss of compressive strength was determined in samples containing 1,5% PVA after 800ºC temperature.

High-temperature effect of a gas jet of reacting components on an inclined plate

The purpose of the research was to experimentally and computationally study the distribution of pressures and heat fluxes when near-design jets of high-temperature reacting mixtures on the oxygen-kerosene, oxygen-methane, oxygen-ethanol components act on an inclined plate in the near field of the jet within the distance equal to nozzle exit diameter for pressure ratio The paper introduces the results of these studies. They were carried out with jets flowing with total temperatures of into ambient environment with normal pressure and temperature. The level of heat fluxes created by the jet on the plate was in range within Calculations in the SolidWorks Flow Simulation environment for the effect of a high-temperature flow for a perfect gas with parameters corresponding to the chemical composition in a model combustion chamber showed good agreement with experimental data.

An investigation on the properties of woodcrete exposed to high temperature

By combining wood wastes with various binders, construction materials can be produced. These materials can be used in non-bearing parts such as wall block, insulation panel. In this study, prismatic specimens were taken from the mixtures produced considering the chip-cement ratio as 0.25, 0.5 and 1. The unit weight, ultrasonic pulse velocity, bending and compressive strengths of the specimens were determined by using the results of the experiments on these specimens. In addition, specimens were kept at 200 and 400°C for 3 hours in order to determine its behavior under high temperature, which is one of the most important problems for wood composites. With the experiments carried out on the cooled specimens, weight and strength losses, changes in ultrasonic pulse velocity were examined. As a result of the study, while determining that the chip-cement ratio can be used as 1, it is recommended to use the chip-cement ratio up to 0.5 when the high temperature effect is taken into consideration.