Experimental Analysis of Fibre Metal Laminates

Abstract

Aircraft structures are prone to impact damages and one of the several methods to overcome this, is to use Fibre Metal Laminates in the construction of structures. Fibre Metal Laminates is a new class of advanced aerospace materials. They consist of thin metallic sheets bonded together with fibre reinforced adhesive matrices. In this work, strength characteristics of fibre metal laminates and fibre laminates are studied and compared as follows; Case I - Fibre metal laminate (Top & Bottom layers of 0.3 mm thick aluminium alloys sheets + 5 layers of (0/90/0/90/0) cross ply glass fibre laminates) is compared with 7 layers of (0/90/0/90/0/90/0) crossply glass fibre laminates and Case II - Fibre metal laminate ( Top & bottom layers of 0.3 mm thick aluminium alloy sheets + 7 layers of (0/90/0/90/0/90/0) crossply glass fibre laminates) with 9 layers of (0/90/0/90/0/90/0/90/0) crossply glass fibre laminates. The specimens are fabricated such that the seven layers FML and seven layers GFRP has the same thickness. Similar, is the case for nine layered laminates. To prepare the surface as per ASTM D 2651 of the aluminium alloy for adhesive bonding, both mechanical and chemical approaches have been employed. Surface pre-treatment would also be able to increase surface tension or change the surface chemistry to enhance adhesion with the aid of a chemical bond. Experimental facilities used for this experiment are, Impact test machine used for impact strength analysis as per ASTM D 5628 FD. The deformation, energy absorbed and force upon impact are considered to evaluate the characteristics of the laminates. From the results, it is concluded that the fibre metal laminates are stronger when compared to the GFRP laminates. The stiffness is more than 3 times higher compared to a GFRP. The energy during impact is also high for the fibre metal laminate. The Fibre metal laminate is able to withstand more than twice the energy compared to a GFRP laminate. Similarly, the force upon impact is also high for the fibre metal laminate which indicates that the fibre metal laminate is stronger when compared to a GFRP laminate