Fibre Metal Laminate

Fibre Metal Laminates (FML) is a kind of hybrid materials and it can be fabricated from an alternating
laminate of thin metal sheets and thin composite layers. Since several variables are involved in the
composition of this laminate, a wide range of different combinations lamination seems to be possible.
Some of these variables are the type of metal alloy, the type of fibres, the type of polymer, the
thickness of layers, the number of layers, the orientation of (fibrous) layers, etc. Therefore, FMLs are
regarded as a family of laminates, and GLARE is the best-known member of these laminates. GLARE
is made from aluminum layers in the range of 0.3–0.5 mm thick, and glass fibre reinforced composite
layers in the range of 0.25–0.5 mm thick . One of the wide used of GLARE composite is in aeronautic
application.
Based on the expected growth of passengers for intercontinental flights within the world, high
capacity aircraft (such as from the Airbus company) are currently developed. To make this airplane
cost effective for the next 30 years, new technologies are being evaluated such as the application of
new aircraft materials. One of these studies investigates the feasibility of using the FML in the upper
part of the aircraft that needs to be fatigue failure resistant, or specifically the structure should be under
damage tolerant design.
Fibre Metal Laminate (FML) can be said to have a high fatigue resistance, with it is achieved
by the intact bridging fibres in the wake of the crack. This condition restrains the occurrence of the
crack opening .Controlled delamination in the material makes some crack opening
possible without failure of the fibres. The fibres transfer load over the fatigue crack in the metal layer
and restrain the crack opening. This phenomenon is called fibre bridging .The
fatigue fibres laminates can be formed and machined like aluminum alloys and have the high specific
strength of composite materials: they combine the best of both worlds. The laminates can be applied in
various thicknesses, e.g. a 2/1 lay-up means a laminate with two aluminum layers and one intermediate
fibre/epoxy layer: [A1/prepeg/A1]. The fibre/epoxy layer at 2/1 lay-up can be multiple cross plied 0/90
layer or be unidirectional.