Analysis of the anisotropic mechanical properties of structural adhesive joints with curing-induced pre-deformations

In modern lightweight construction, multi-material design has become increasingly important. An increasing number of structures are being adhered because adhesive joining technology can be used regardless of the material of the bonded partners. Owing to the dissimilar coefficients of thermal expansion, thermally induced relative displacements of the adherend occur during heat curing. Following these pre-deformations, changes in the mechanical properties of adhesive joints were observed. In this study, thick adherend shear specimens were used to induce defined relative displacements in the shear plane during the curing process. Quasi-static tests showed a directional dependence in the pre-deformation. This anisotropic behaviour was investigated in detail. Results showed that shear band formation occurred in the adhesive owing to the load during the cooling of joined structures. The restructuring of the polymer structure leads to changes in the mechanical properties.