Experimental investigation of porosities evolution in a bonded assembly by means of X-ray tomography

ABSTRACT Structral bonding is a very advantageous technique for lots of application fields such as aeronautics or marine industry, which require both advanced performances and lightweight structures. Nonetheless, adhesive joints are often subject to bonding defects: kissing bonds, uneven polymerisation, or pores within the material, for instance. These pores, depending on their sizes and distributions, could jeopardise the mechanical strength of the assembly. Moreover, it is legitimate to hypothesise that these voids in the medium could be influenced by the application of a mechanical stress. In order to investigate this assertion, bonded samples are loaded by various tensile stress levels, and the pores within the joint are visualised and characterised using in-situ X-ray microtomography. This paper deals with the evolutions of various quantities such as the number of pores or their volumetric ratio along with the increasing load and with the diverse phenomena (nucleation, growth, coalescence, etc.) experienced during the testings. These results are extracted from the microtomographic data using a custom processing tool, whose parameters and performances are discussed.