Determination of fatigue life for different R-ratios of the off-axis unidirectional hybrid (GFRP/Al) composite laminates

The developments that took place in the aircraft and space industry reveal the need for new and superior materials. Composite materials have begun to be used to meet these needs. In particular, the use of fiber reinforced composites in manufacturing and industrial field has increased considerably. Fiber-reinforced composites are the most preferred type of fiberglass when considering the sales quantities and consumption rates. In this thesis, composite plates of glass fiber reinforced plastic / aluminum (GFRP/Al) layers were produced in hybrid form and test specimens were prepared from these plates. Before the fatigue tests, static tests were performed so that the load values required for fatigue were determined. Fatigue tests were then carried out at these load values. Thus, fatigue life of GFRP/Al based layered composites was determined. The fatigue lives of GFRP/Al layer composites were determined for different fiber orientations (θ = 0o, 15o, 30o, 45o, 60o, 75o, 90o) and loading ratios (R = 0,3; 0,1 and -0,1) the results are compared with each other. The results show that the samples have the highest fatigue life in the fiber orientation direction at R = 0, 3 loading rate and the fatigue lives of the samples decrease as the loading rate decreases. In addition, loading rate changes have also resulted in fatigue life of the end resultant materials independent of the orientation sequence.