Flexural behaviour of laminated fibre composite sandwich beams

Abstract

A new generation composite sandwich made up of glass fibre reinforced polymer skins and lightweight but high strength core material has been developed in Australia. Experimental investigation was conducted to determine the behaviour of this composite sandwich with a view of using this material for structural beam. As these sandwiches are produced in limited thicknesses, the structural beam section could be attained by gluing a number of sandwiches in the flatwise (horizontal) or edgewise (vertical) positions. Characterisation of the behaviour of individual sandwiches as well as beams with 2, 3 and 4 composite sandwiches glued together was conducted. The results showed that the composite sandwiches in the edgewise position has a 9% lower effective modulus of elasticity in bending than in the flatwise position. However, it failed at a 20% higher load with a different failure mode. The specimens in the edgewise position failed with greater ductility due to progressive failure of the fibre composite skins while the specimens in the flatwise position failed in a brittle manner due to core shear failure followed by delamination between the skin and the core. These initial results are very encouraging. With further investigation, the development of structural beams from these fibre composite sandwiches could be realised.