Disbond-Stopping Concepts for Bonded Composite Joints

摘要

Bonded composite joints have many advantages in comparison to conventional fasteners. However, adhesive bonding of primary aircraft structures is still a certification issue. One promising way to achieve airworthiness for bonded composite joints in accordance with the authority requirements is the establishment of disbond-constraining design features. Consequently, two novel design features are developed. On the one hand, the hybrid bondline is introduced as a combination of adhesive bonding and local thermoplastic welding. On the other hand, an array of small diameter pin elements is used as out of plane reinforcements. Enhanced manufacturing concepts are developed for both features. Their mechanical performance is evaluated by means of static and fatigue tests. Both principles are proven successful since crack growth is fully stopped for both technologies in fatigue crack lap shear (CLS) tests under relevant loading conditions. Thus, it can be concluded that these technologies are a promising step towards certification of bonded composite joints.