The effect of different environmental condition on the static and dynamic strength of laminated composites

Properties such as stiffness and lightness have come into prominence by developing technology in engineering application. This circumstance caused to unavoidable usage of composite materials which is as durable as conventional metallic materials and lighter than it. Composite materials occur by coming together two or more materials in macro scale to make a new material having superior properties than own properties. Composite materials have been used as structural material in land, sea, and air vehicle also building industry and defense industry due to their properties as ultra-impact and corrosion resistance, high rigidity, lightness and good thermal conductivity. The mechanical properties of composite materials change according to used fiber and matrix. Therefore ambient conditions, where this type of composite will be used, and stress situation on the structure must be well known, after that fiber and matrix material should be chosen this phenomenon. Polymer based composites can be loss their strength by negatively affecting from environmental conditions such as temperature, ph, and moisture etc. Many of engineering materials are working under cycling load during usage. The materials which is working under dynamic loading, can be damaged even under their yield strength. Under dynamic load, creating of crack on the surface of material, progressing of crack, and following that fracturing is named fatigue. The fatigue life of composite materials can be decreased in improper ph environments. For that reason, the fatigue life of composite materials, which works at acidic and basic atmosphere, must be known in case of workers and job safety. Static strength, fatigue life and failure mechanism of pure glass, pure carbon and glass-carbon reinforced hybrid composite materials, which retained into acidic and alkali environments, will be investigated with this project. In this content, glass/epoxy (C8), carbon/epoxy (K8) un-hybrid composites and glass-carbon/epoxy (C2K4C2), carbon-glass/epoxy (K2C4K2) hybrid composites having eight layers will be produced by using hand lay-up method. The produced composite materials will be retained into acidic and alkali solution having 5%, 15%, and 25% concentration along 4, 8, 12, and 16 weeks. To understand the environmental condition effects on the internal structure of hybrid and un-hybrid composites, scanning electron microscope (SEM) image belonging each structure will be taken before fatigue test. Fatigue life under flexural loading will be defined in load value which equal to 80%, 70%, 60%, 50%, and 40% of bending strength. To describe failure mechanism of damage which occurs after fatigue, SEM image of damaged specimens will be taken. Also, to better understand of environmental condition on the fatigue life, results will be compared with results of hybrid and un-hybrid composites, which didn't retained into any environments (0%). Although there are studies about fatigue life in the room temperature of different hybrid structures, there is not study about the fatigue behavior under acidic and alkali environments. The usage of composite materials in our country increasing every passing day in the industry branches given above. The aim of this prepared project is determination of static and dynamic (fatigue) behaviors the fatigue life of glass-carbon composite materials, which retain into different environments. Project results will present beneficial knowledge's in terms of both manufacturing and economical for composite manufacturing firms (especially automotive parts, wind tribune, and composite structure materials) in our country. In addition, the acquired experience of project team during working time and to be done publication study will be the other important output of this project.