This paper analyses the influence of surface roughness on adhesive bond strength. Numerical simulations were performed to evaluate the influence of geometry on the performance of structural adhesive joints. The objective is to create a model to describe the behaviour of the interphase of adhesive joints according to its geometry. Two-dimensional simulations with theoretical geometries were performed considering parameters of roughness, stress distribution, and contact area to verify the qualitative influence of substrate topography on the adhesion of a joint. Numerical analyses were done to verify the effect of the interpenetration of materials on the mechanical properties of the interphase.