Three-way interaction modeling of structural deformation, adhesive flow, and adhesion in hybrid aircraft assembly

During the assembly of modern aircraft structures, an adhesive (sealant) layer is applied to the joint at a certain stage. During subsequent operations, the gap between the assembled panels may open locally. The presence of adhesive significantly affects the gap opening since appreciable adhesion is observed between the adhesive and the panels. The present work is devoted to the development of a mathematical model that enables the simulation of aircraft assembly processes while accounting for the adhesion phenomenon. The intermediate state of the assembly is determined by three main physical processes: deformation of the panels accounting for possible contact, adhesive flow, and adhesion. The developed model resolves all these processes and is therefore referred to as a three-way interaction model. In the structural part, the contact problem is reduced to a quadratic programming problem. A distinctive feature of the proposed approach is the combination of the Reynolds lubrication approximation, typical for liquid-state adhesives, with the local interface RCCM model, conventionally used for solid-state contact, for the description of the macro-scale debonding process. To demonstrate the performance of the proposed model, a test problem of typical aircraft panel assembly is considered. The numerical results show that, for certain values of the problem parameters, the adhesion phenomenon has a direct effect on the assembly outcome and cannot be neglected.