Community Research and Development Information Service - CORDIS

Damage tolerant design of fibre reinforced plastic sandwich structures

A wide collection of damage sources, failures and damage types for typical aeronautical, naval and automotive applications has been catalogued. Low velocity impact damage and debonding of skins were identified as damages which occur most frequently and affect the structural behaviour most severely. A major part of the project was the development of strength prediction models. Three different types of damage were investigated: impact damage, disbond between core and skin and flawed butt-joints. Based on experience with fibre reinforced plastic (FRP) laminates 3 prediction methods were developed. The experimental data obtained showed an acceptable agreement with the analysis results. Parallel finite element models, generated with a general purpose code, have been used for investigations focusing on fracture test specimens.

The second part of the programme concerned the development of analytical and numerical tools to predict the fatigue life of damaged sandwich structures. The more sophisticated models are based on finite element modelling of the damaged region taking into account micromechanical failure modes and fatigue damage mechanisms, energy release rate or material degradation observed in the experimental studies. The models also showed a strong dependence on the used procedure and the initial geometric description and they induced numerical stability problems. In the experimental field more than a thousand specimens have been manufactured. Additional real structures components used by the industrial partners in their products have been used for non-destructive examination and static and fatigue testing. In this project relatively few methods were used for inspection. These methods and other possible methods like sherographic inspection, thermographic inspection and mechanical impedance scans, were evaluated and compared. Damage detection and monitoring during operation was also evaluated.

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Eurocopter Deutschland GmbH
81663 München
Germany
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