Overview
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This technological project originated from the observation that there has been little evolution in the field of aeronautical wiring over the last 25 years and that the current 'wire by wire' technologies, although reliable, easy to implement and flexible in terms of use, were showing their limits in addressing the critical changes currently in progress.
This resulted in the need for the 'development of a new flat concept', for general electrical harnesses and standard airframe cables and connectors.
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- 10% minimum on weight
- 30% minimum on implementation times
- 20% minimum on overall costs
- improvement of advanced design tools
-
improvement of safety:
- guarantee reproducibility and precise knowledge of the position of each signal in the harness
- optimise the electro-magnetic resistance and thermal protection required for each type of signal
- eliminate a large number of individual screening connections
- work no longer performed 'wire-
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The proposed approach comprised several independent parts:
- design of a new modular flat harness concept
- study of the distribution of the electrical signals
- definition of the rules, directives and associated IT tools
- design of components ( to be standardised)
- concept validation process.
Funding
Results
All results detailed in the EECS Final Report show that a flat cable concept is a feasible alternative to the open bundle solution currently being used.
Four points need to be highlighted:
- Foil screen efficiency is sufficient to cover crosstalk needs when signal allocation models are available. This screening technology is easy to implement and is of particular interest for bundles with numerous shielded jacketed cables inside due to weight and implementation time saving. This will be the case for aircraft with composite structures.
-
A very cheap and innovative contact technology inside simple modules was developed based on a stamp instead of machined technology. If stripping is necessary, no tool is required to make the contact / cable conductor interface. Vibrations test results confirmed feasibility for this.
These contacts are integrated in small modules. -
To apply these concepts on a large scale wiring tool, the main issues will be the integration of
pre-designed allocation models to cover the various type of signals and
geometrical constraints brought by the rectangular shape of the bundle
(no flexibility in one direction).
This integration involves more work than originally expected. - As ribbon cables use sets of conductors and in order to limit risks from unused conductors and associated weight penalties, these two concepts will have to co-exist.
This new concept, which still addresses the medium term, will be able to bring the following savings for a given perimeter:
- 10% minimum on weight
- 300% minimum on implementation times
- 20% minimum on overall costs.
Furthermore, impossibility of error insertion, reproducibility of signal positioning and the possibility of putting sensible cables inside the bundle in order to protect them from possible external mechanical or electrical aggression are major factors in guaranteeing an improvement in the quality of the electrical signal distribution.