Contribution À la Prise en Compte Des Effets de L'environnement Sur la Tolérance Aux Dommages D'impact de Stratifiés Composites

Résumé du livre

The extensive application of composite laminates in aeronautical industries demands a thorough understanding of their mechanical behaviours and damage. The prediction of impact behaviour, impact damage and the associated mechanisms under complex environmental effects remain still an open issue. The effects of various humid ageing conditions (No ageing, 65% relative humidity and 90% relative humidity ageing) and environ mental temperatures (room temperature and 80°C) on the intra-Iaminar and inter-Iaminar properties are characterized. A particular emphasis is laid on the study of different non linear behaviours of in plane shear. A progressive damage model based on continuum damage mechanics is proposed to describe intra laminar mechanical behaviour by taking into account the identified in-plane shear nonlinear phenomenon. This model is then applied in numerical simulation on low velocity impact combined with cohesive law in interface to predict the impact response and associated damage (ie. Fibre failure, matrix cracks and delaminations). The damage model is implemented in LS Dyna as user defined material laws.lmpact tests on laminate coupons with different stratifications are performed to validate the numerical simulation. Good agreement is achieved especially for nonaged material under room temperature between numerical and experimental results in terms of contact force history, platedeflection and impact duration. By means of non-destructive inspection, the impact damage is coherent with predicted results concerning fiber damage location, matrix cracks especially the through thickness delamination.