Investigation of the performances under environmental conditions of composite materials produced by pultrusion method

The use of composite materials in the industry is increasing day by day. The use of composite materials produced by the pultrusion method is very common, especially because of their cost-effective and high corrosion resistance properties. Therefore, from past to present, the mechanical behavior of composite materials produced by pultrusion is investigated in different studies. In this thesis, some of the glass fiber reinforced polymer matrix composite profiles produced by the pultrusion method were subjected to environmental tests according to the military standard MIL-STD 810 w/Change 1, and some of them were subjected to continuous ambient conditions (+23°±2°C, 50±10% RH). U, I and box profile composites produced by pultrusion method were subjected to environmental conditions such as high temperature, low temperature, temperature shock, salt fog, rain and low pressure (altitude). The changes that may occur on the surfaces of the composite profiles exposed to environmental conditions tests were examined and recorded. In addition, in order to observe the changes that may occur in the internal structure of the samples, the internal structures of the samples were examined with the X-RAY method, which is one of the non-destructive testing methods. After that, test specimens were prepared in accordance with ASTM standards for three-point bending, tensile and Izod notch impact tests from composite profiles, and mechanical tests were carried out according to the relevant standards. The mechanical properties of composite materials exposed to environmental tests and composite materials under continuous ambient conditions were examined and the results were compared. As a result of experimental studies; It has been observed that environmental conditions have significant effects on the mechanical properties of composite materials. In general, when the results were compared with each other, it was observed that the mechanical properties of the composite materials subjected to the low temperature test were higher, and the mechanical properties of the composite materials subjected to the salt fog and rain tests were lower. When examining the effect of temperature on the mechanical properties of composite materials, it was observed that the mechanical properties of composite materials subjected to high temperature tests were lower than the mechanical properties of composite materials subjected to low temperature tests. The mechanical properties of composite materials subjected to low pressure tests have been slightly lower than the mechanical properties of composite materials exposed to low temperatures.