Abstract :
Fibre Metal Laminates (FML) represent a
family of hybrid materials, consisting of alternating layers
of thin metal sheets and fibre reinforced epoxies. The
concept, invented in the late 1970s, has resulted in laminates
like ARALL and GLARE. The first material is made
of aluminum alloys, aramid fibres and an epoxy resin,
GLARE laminates use similar constituents except for the
aramid fibres, which are replaced by glass fibres. Besides, a
specific laminate is determined by its layer thickness, fibre
orientation, number of layers, etc., parameters, which can
be regarded as variables. The first large scale application of
the GLARE laminates is the fuselage of the Airbus A-380
aircraft. Large sections of the fuselage, both in the front
and aft section will have a GLARE skin and some local
GLARE doublers. Before this material could be applied to
the A-380, it took more than 20 years of research and
development, and the R&D is still continuing. The research
that is performed is a mixture between testing and modeling:
testing is necessary for the optimization of the
laminates, and a lot of test evidence is required for certification
and qualification purposes. In addition also analytical
and numerical tools have been developed to limit
the number of tests, to determine design allowables, and to
predict the material behavior in a multitude of structural
applications and details. Current and future research on
FML has at least two objectives. On one hand the research
is focused on generating new laminates based on the same
concept, on the other hand the modeling is advancing in
order to improve existing models and to develop new ones
(tools for the analysis of structures). The tendency for the
modeling is from macro-scale towards meso- and even
micro-scale modeling. From the modeling and experimental
point of view these hybrid materials, mixtures of
metal and composite layers, offer specific challenges. Since
fibres are embedded in the matrix and the materials have a
layered structure, typical composite characteristics and
failure modes are involved like anisotropy, fibre–matrix
interfaces, matrix cracking, and delamination. On the other
hand due to the metal constituents the laminates show
plastic behavior and have discrete interfaces between the
metal and the resin. In this paper an overview is presented
of the research and development of FML, in particular the
development of GLARE. The emphasis in this overview
will be on the understanding and analysis of these laminates,
and the development of appropriate tools (models).
Over the years the development was a concurrent one: both
testing and modeling were performed simultaneously.
Special attention will be paid on the current and future
research that is planned for a further understanding of this
structural material. This research is dominated by numerical
calculations and simulations and is aiming for topics
like the prediction of the fracture energy, the crack bridging
effect, and the blunt notch behavior of laminates.
Introduction
Fibre Metal
