Etude du vieillissement de liaisons adhésives en milieu marin pour application offshore

This thesis work was performed with a view to offshore applications, and the aim is to improve understanding of the the long term behaviour of adhesive bonding in a marine environment, in order to replace welding by adhesive bonding on offshore platforms. An experimental method has been developed to collect the data required for a numerical model, to predict the life expectancy of adhesively bonded structures. There are several objectives, the first is to understand the mechanisms of failure of adhesively bonded joints and to evaluate the kinetics of their degradation. So, in a first step, the water absorption of bulk adhesives has been studied under different aging conditions, and its influence on the mechanical and physico-chemical properties of the adhesives was evaluated. In parallel, the mechanical characterization of two kinds of adhesively bonded assemblies during aging was performed. The second objective is to develop a finite element model of the hydro-mechanical behaviour of assemblies, taking into account the evolution of the properties of the bulk adhesives during aging. The validation of this model has been evaluated by comparison with the experimental results obtained from the study of the aging of adhesively bonded assemblies. In parallel, a method of non destructive control of adhesively bonded assemblies has been developed, based on Impedance Spectroscopy which has been applied to the measurement of the water uptake of bulk adhesive and assembled joints.