Experimental identification of pore opening, growth and coalescence in a bonded assembly using X-ray μ-tomography
Identification expérimentale de l’ouverture, de la croissance et de la coalescence de pores dans un assemblage collé, en utilisant la µ-tomographie aux rayons X
Résumé
Structural bonding is increasingly used in various industrial sectors such as i) naval, ii) automotive
and iii) aeronautics [1]. The adhesives traditionally used in the context of structural assemblies are
two-component epoxy adhesive type (resin and hardener). Thus, during the resin-hardener mixing
phase, but also during the polymerization step, it can be observed the appearance of the pores in the
joint. The size and distribution of the pores are greatly influenced by the nature of adhesive components, their viscosity, their temperature, mixing time, etc. It can be observed experimentally [2] that this population of porosity considerably influences the mechanical strength of the seal and consequently leads to the degradation of the adhesive. Naturally, the changes in the morphology of the joint could be due to mechanisms (opening, growth, coalescence of the pores), occurring during the mechanical loading of the joint. So, the objective of this study concerns the establishment of a robust strategy for the experimental identification of these damage mechanisms, using X-ray μ-tomography. The proposed strategy is built first from synthetic tomographic data for which the appearance of the different mechanisms (opening, growth, coalescence) is mastered. The effect of voxelization of porosities on the identification of these mechanisms is studied and a coalescence criterion is proposed. The second step aims to validate the proposed strategy, using semi-synthetic data obtained from the results of a finite element model. Finally, the strategy is applied to two concrete cases: a monotonic tensile test on a bulk sample and a tensile test on a bonded joint based on a mini-scarf type sample stressed in the out-of-plane direction.
Domaines
Mécanique [physics.med-ph]Origine | Fichiers produits par l'(les) auteur(s) |
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