Advanced analytics of elastic adhesive bonds by means of in situ computed tomography

This paper addresses optimization of parameters and measuring setups for in situ computed tomography measurements on marker particle-filled adhesives. The focus of this work was to increase the detail detectability and discriminability between used marker particles and surrounding adhesive compound even for materials with a high X-ray attenuation. Therefore, it is necessary to reduce the effects of artifacts like scattered X-rays and beam hardening, respectively. A key benefit of being able to distinguish different materials clearly improves the correct interpretation of the reconstructed three-dimensional volume significantly, while a reduction of artificial disturbances enhances the possibility to visualize previously overlaid undetected details, e.g. air voids. Performing in situ computed tomography measurements by applying the optimized parameter setups, cavitation formation was observed investigating the particle behavior of specimens modified with glass beads as marker particles under applied load. An achieved bonding enhancement by using a coupling agent as pre-treatment for glass beads was also proven by means of in situ computed tomography. Furthermore, the parameter setups optimized for bulk specimen could be adapted on material combinations, e.g. single-lap shear specimen, by adjusting a few parameters. Additional experiments demonstrate that computed tomography measurements can also be used for analytical purposes, for instance to evaluate the mixing quality of the so-called QUADRO™ or 2C mixers for two-component adhesives.