Paper number 926


T. Risson, O. Ceysson, and M. Salvia

Laboratoire d'Ingénierie et Fonctionnalisation des Surfaces, UMR 5621
Ecole Centrale de Lyon, BP 163, Ecully Cedex, 69131, France

Summary Carbon fibre reinforced plastics (CFRP) offer high specific mechanical properties (performance vs. weight ratio). Thus during the last decade, they have been increasingly used as components in engineering structures and particularly for aeronautical applications. However, this type of complex material with organic matrix shows, even at the room temperature, mechanical characteristics depending strongly on the duration of loading and/or the stress or strain rate. This behaviour is obviously amplified by an increase of temperature or by a particular environment as the occurrence of moisture or low-molecular weight plasticizing agent (jet fuels, lubricants or other hydrocarbons). So, concerning the design of such structural components, one of the most important feature of the long-term durability and dimensional stability is to take account of their long-term viscoelastic behaviour. To fore see the long-term integrity of a composite structure, the viscoelastic behaviour of the polymeric part of these materials have to be understood.
In this contribution a long-term prediction method for creep behaviour of off-axis CFRP (unidirectional 90° and [±45°] laminates) is proposed using both the classical time-temperature-stress superposition principle (TTSSP) and a new microscopic approach based on a theory of the non elastic deformation of amorphous polymers developed from a model of molecular mobility.
Keywords CFRP, flexural creep, long-term behavior, TTSSP, molecular mobility, amorphous polymer.

Theme : Mechanical and Physical Properties ; Creep and Viscoelastic Behaviour

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