Experimental and numerical investigation of the effect of graphene addition to carbon fibre reinforced aluminium plates (CARALL) on mechanical properties

The requirement for high performance lightweight aircraft, especially in the field of aviation, has necessitated the use of new production methods and innovative materials. Fibre metal laminate (FML) composites developed for this purpose offer a solution in advanced engineering applications with their unique properties such as high specific strength, extraordinary energy absorption capacity and excellent impact resistance. In areas requiring high performance such as aerospace, automotive and defence industries, FMLs combine both the toughness properties of metal and the light weight of composites, creating an unrivalled material option. CARALL (Carbon fibre reinforced aluminium laminate) is a new generation FML that combines the light weight and high strength properties of carbon fibre with the toughness of aluminium, offering significant advantages in areas that require high performance and safety, such as the aviation industry. It provides superior impact resistance and energy absorption compared to conventional composites, as well as high fatigue strength, low density and corrosion resistance. In aircraft structures where the potential for low-speed impact is high, situations such as stone impact during take-off, equipment drop during service or object impact at rest pose structural risks. Therefore, the low speed impact behaviour of CARALL FML composites is an important issue. In this study, the effect of fibre orientation and Graphene Nanoparticle (GNP) doping on CARALL FML composites, which are relatively new members of the FML family, were investigated by experimental and numerical methods. In the study, the mechanical properties of CARALL materials by tensile and 3-point bending tests, as well as the effect of low velocity impact behaviour at different temperatures (-40 °C, 23 °C and 80 °C) and different energy levels (23J, 33J and 48J) were investigated using non-destructive testing methods. In addition to these, low velocity impact tests at room temperature were verified experimentally and numerically in order to guide the design optimisation of CARALL materials in the future. As a result of the study, no significant effect of GNP additive was observed in tensile and 3-point bending tests where fibre orientation was more effective. In low speed impact tests, it was observed that the specimens with 0°-0° fibre orientation showed better results in terms of both damage and maximum peak load. Temperature was found to be effective on low speed impact behaviour. Experimental and numerical results were found to be compatible with each other.