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Fibre composites are being used in aviation for a very long time now. The outstanding characteristics of fibre
composites have been used in the German aerospace industry for the past 50 years. EUROCOPTER Deutschland,
formerly the helicopter division of Messerschmitt-Bölkow-Blohm, consistently applied the advantages of
fibreglass reinforced composites for the rotor blades of the helicopter BO 105. The virtually unlimited lifetime of
these rotor blades also influenced the development of the bearing less main rotor of the EC 135.
In the beginning fibre composites have mainly been used for components not subject to significant stress, such
as fairings, doors and horizontal stabilizers. Intensified use of fibre composites in other industrial sectors has
also led to falling prices for fibres and resins, which has in turn led to an expansion of use. Eurocopter established
the necessary expertise in the area of airframe structures e.g. by developing an entire BK117 airframe
from fibre composites. This research project contributed to the breakthrough of fibre composites in the Tiger
and NH90 programmes. Actual research projects are focused on the development of cost-effective production
methods, in order to further enhance the use in civil helicopter construction.
Prof. J. Szodruch
John M. Griffith
Dr Jocelyn Gaudin
10
The specifications for helicopter airframes and blades can be derived from customers’ requirements: high payload,
low maintenance expenditure, resistance to corrosion, and high level of safety combined with maximum
comfort. The advantages obtained by using fibre composites are clearly evident. Highly integrated assemblies
or individual components can be designed and manufactured with specifications optimized to match requirements
and minimum weight. Todays prepreg technology may reach in some areas its limits with regard to
producibility and production costs. Hence new production processes and more automated manufacturing has
to be developed. The following paper gives an overview of the latest improvements.
Title: Fibre optics distributed sensing: Status and perspectives
Authors: Prof. A. Güemes
Polytecnic University of Madrid
Time: November 3, 2009 1:40 pm
Room: Lumen
Getting the strains all along the optical fiber, with adequate spatial resolution and strain accuracy, open new
possibilities for structural tests and for structural health monitoring. Formerly, only point sensors, as strain gages
or FBGs, were available, and information on the response to loads was restricted to those points onto which
the sensors were bonded. Unless some sensor was located near to the damage initiation point, details about
the failure initiation and growth were lost. With a distributed system the information is given as an array of
data with the position in the optical fibre and the strain or temperature data at this point.
In this paper the physical principles underlying the different techniques for distributed sensing are discussed,
a classification is done based on the backscattered wavelength; this is important to understand its possibilities
and performances. The definition of performance for distributed sensors is more difficult than for traditional
point sensors, since the performance depends on a combination of related measurement parameters. For example,
accuracy depends on the spatial resolution, acquisition time, distance range or cumulated loss prior to
measurement location.
The field of applications of this new technology is very wide; Results of the structural tests of a 40 mts long
wind turbine blade, detecting the location and load of onset of buckling, and the results of the delamination
detection in a composite plate, are presented as examples.
Title: An Experimental Investigation into Frictional Effects in Bolted Joints
Authors: M. Oswald, W. Stanley, C. McCarthy
University of Limerick
Time: November 3, 2009 2:00 pm
Room: Lumen
Bolted joints form critical elements in composite aircraft structures and their design is heavily influenced by
friction acting at the interface between the joined members. In fully torqued joints, most of the load is transferred
through friction at this interface, with only a small percentage being transferred by contact between
the bolt and laminate. This is the most desirable situation, therefore to take full advantage of this phenomenon
designers need a full understanding of the coefficient of friction (COF) at this interface. The static and dynamic
COF at the interface in joints can vary over time due to wear, for example. Hence, this paper sets out to experimentally
measure the COF between bolted composite laminates and between bolted composite laminates and
aluminium. In this study, a versatile friction testing rig was designed and commissioned. This rig was mounted
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