Durabilité des époxys ; application au collage structural aéronautique

Abstract : This thesis deals with a multi-scale study of the ageing of bonded assemblies based on epoxy adhesive used in the aeronautical field. In service conditions, these materials are subjected to humid ageing, which can be accompanied by thermal ageing essentially during the take-off phases of aircraft. Such conditions make it difficult to predict lifetime based only on the study of the mechanical properties of the assemblies (by single lap shear stress or wedge tests) in standardized ageing tests, which, for the moment, prevail in the industry. Our objective was therefore a study of ageing at the molecular scale in order to derive forward kinetic laws predicting the kinetics of degradation. A first step highlighted the differences between humid ageing (adhesive failure) and thermal aging (cohesive failure). The cohesive rupture observed in thermal ageing led us to study the mechanisms responsible for the decrease in toughness of the epoxies. We studied the mechanisms of degradation of the adhesive as well as two of its "representative" systems (DGEBA-DDS and TGMDA-DDS). The analysis of degradation products in these networks and their model compounds led us to develop a kinetic scheme introducing the reactivity of the main oxidation sites (site near certain heteroatoms) which can partly describe the oxidation of simple systems. In the future, DGEBA-DDS and TGMDA-DDS will have to be converted into a co-oxidation model (that means integrating the simultaneous participation of several sites) to describe entirely the oxidation of simple systems but especially for handled industrial materials of complex formulation. In a last part, we were interested in the specificity of bonded assemblies during humid aging. This last section displays the need to understand diffusion phenomena at the interface, and in oxidized materials, to predict the lifetime of epoxy adhesives used for bonded assemblies.
Complete list of metadatas

Cited literature [303 references]  Display  Hide  Download

https://pastel.archives-ouvertes.fr/tel-02194167
Contributor : Abes Star <>
Submitted on : Thursday, July 25, 2019 - 11:48:07 AM
Last modification on : Tuesday, September 3, 2019 - 3:30:11 PM

File

DELOZANNE.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02194167, version 1

Collections

Citation

Justine Delozanne. Durabilité des époxys ; application au collage structural aéronautique. Mécanique des matériaux [physics.class-ph]. Ecole nationale supérieure d'arts et métiers - ENSAM, 2018. Français. ⟨NNT : 2018ENAM0071⟩. ⟨tel-02194167⟩

Share

Metrics

Record views

158

Files downloads

73