Investigating the Phenomenon of Flutter as well as the Mechanical and Microstructural Properties of Layered Composite of Aluminum Sheet with An Epoxy Matrix Reinforced with Carbon Fibers

Flutter is an example of an aero-elastic phenomena that involves analyzing the interaction between elastic and aerodynamic forces, both static and dynamic. This study examined the effects of the stacking of polymer and aluminum layers on the modal frequency, drop weight impact, and tensile characteristics of polymeric composites and Fiber Metal Laminates (FMLs) incorporating carbon fibers. In this study, Carbon Fiber Reinforced Plastic (CFRP) laminates were used in the FML composite specimen. Based on a hand-lay-up method, ۲۰ layers of carbon fiber prepregs were used to fabricate the specimen, i.e., Al/۴CFRP/Al (Al۲C۱) and then, Al/۴CFRP/Al/۴CFRP/Al (Al۳C۲) fiber metal laminates with two stacking arrangements were made. The surfaces of the aluminum sheets were treated through an anodizing method to improve the adhesion between aluminum and polymer layers. The fracture surface of the specimen was investigated using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). The mechanical properties along with the vibration behavior of specimen were also studied accordingly. The results showed that Al۳C۲ had the greatest values of the required frequency for vibration and lowest stress brought on by vibration, with ۰.۰۰۰۸ MPa for the initial state. Additionally, the FML sample demonstrated a higher frequency and less stress from vibration than the CFRP specimen with the same thickness. According to the findings of the impact tests, CFRP and Al۳C۲ had the lowest (۲۱۰ KJm-۲) and the highest (۹۶۰ KJm-۲) values, respectively. However, due to the lower weight of Al۲C۱ than that of Al۳C۲, the specific absorbed energy value of the former was higher (۴.۷ Jm۲kg-۱) than that of the latter (۲.۳ Jm۲kg-۱). In tensile testing, Al۳C۲ was characterized by the best tensile properties (i.e., yield strength of ۵۸۰ MPa and ultimate tensile strength of ۸۹۷ MPa) compared to other samples. The current study demonstrated that compared to other specimen, Al۳C۲ possessed the least potential to flutter occurrence in a possible real situation.