Generalized analytical solution for compressive forces in adhesively-bonded-joint assembling

Normal forces exerted by the adhesive to the substrate during the squeeze flow occurring in compaction of bonded joints are analyzed using theoretical, numerical and experimental techniques. An analytical solution, derived from the squeeze-flow theory of a viscoplastic material, is generalized to be valid for any initial shape of the adhesive cord. The rheology of the material is modeled according to the Herschel–Bulkley model and is fitted with experimental data available from the characterization of an epoxy-based adhesive. The analytical law is compared with a numerical model, where the two-phase problem for the squeeze-flow test is solved by finite-volume methods using a commercial CFD solver. The results obtained with these two approaches show excellent agreement with experimental forces obtained for a wedge-shaped specimen. The proposed methodology can therefore be useful for the optimization of the bond lines in assembling processes.