Formability analysis of Fiber Metal Laminates using rubber sheet and forming techniques

Fiber Metal Laminates (FMLs) such as GLARE and CARALL being light weight, strong and having high fatigue resistance are widely used in manufacturing of large aerospace/automobile parts. These parts/structures generally have larger radius profile curves and simpler design such as aircraft fuselage or flap skins etc and usually processed by autoclave molding techniques which have very long process time. Due to lengthy process time of such processes or tendency of fracture of layered/bonded structure if traditional sheet forming techniques are used, FMLs have not been considered for fabrication of parts with relatively smaller diameters and more complex shapes. This study attempts and investigates a new methodology to form relatively smaller and complicated parts using traditional sheet metal forming technique. Two Aluminum (Al-2024) layers each 0.8 mm thick are used as outer layers and a flexible Silicone rubber sheet with 1 mm thickness is used as core layer during forming. Gap between die & binder and shape as well as size of blanks have been considered as important process variables for a punch displacement upto 40 mm. Effect of presence of rubber sheet on forming of Al is also studied in details. The results show that die-binder gap and blank holding force are most critical factors which effect formability. The final product showed wrinkles due to presence of rubber sheet. The new method is very efficient to produce hybrid parts made of metal-composite materials. Future work has been suggested to further optimize the process, material and part quality. This study will expand the application areas of metal forming and will open new avenues for the experts working on weight, strength, vibrations and heat transfer areas for future research.