Free Vibration and Buckling Analysis of Carbon Laminated Aluminium Reinforced Epoxy

Abstract

Less weight and recovers injury acceptance characteristics were the most major drivers to advance original family of things for the aerospace/aeronautical industries and for structural engineering purpose. Meant to this objective, a fresh light weight Fiber/Metal Laminate (FML) has been established. This mixture of metal and polymer composite laminates can generate a good effect on various properties. The mechanical properties of FML shows advances over the properties of both aluminium alloys and composite materials independently. Due to their outstanding properties, FML are being used as fuselage skin structures of the next generation commercial aircrafts. One of the benefits of FML when related with straight carbon fiber/epoxy composites is the low moisture absorption. The moisture absorption in FML composites is gentler when compared with polymer composites, even under the comparatively harsh conditions, due to the blockade of the aluminium outer layers. Due to this favourable atmosphere, recently big companies such as EMBRAER, Aerospatiale, Boing, Airbus, tata ,audi and so on, starting to work with this kind of materials as an another to save money and to assurance the safety of their jets. Carbon Laminate Aluminum Reinforced Epoxy (CLARE) is a new variety of fiber metal laminates for advanced aerospace structural applications. It consists of thin aluminium sheets bonded together with unidirectional or biaxially reinforced adhesive prepreg of high-strength carbon fibers. CLARE laminates offer a unique combination of properties such as outstanding fatigue resistance, high specific static properties, excellent impact resistance, good residual and blunt notch strength, flame resistance and corrosion properties, and ease of manufacture and repair. CLARE laminates can be tailored to suit a wide variety of applications by varying the fiber/resin system, the alloy type and thickness, stacking sequence, fiber orientation, surface pre-treatment technique, etc. The present work deals with the theoretical and experimental analysis of CLARE composites. Finite element method in conjunction with Hamliton’s principle have been used to derive the equation of motion. The resonant frequencies have been determined for a CLARE composite with symmetric carbonepoxy composite [0/45/90/90/45/0]. Experiment are carried out to determine the resonant frequencies, using the sine sweep method. Though the theoretical and experimental values are fairly nearer, there is some difference. The experimental values are found to be less than the theoretical values. The reason may be due to the lack of perfect bonding between the layers, as have been assumed. Imperfect bonding increases the flexibility of the beam and hence there is drop in the resonant frequencies. The experimentally determined buckling load is also less than the theoretical values, the reason may be due to imperfect bonding between layers and inaccurate estimation of the material properties.