Effect of grooves on the strength of adhesively bonded joints

The objective of this work was to study the influence of the macroscopic state of the substrate surface on the strength of adhesive joints. For that, several patterns were made on the surface of aluminium substrates. The patterns were tested in two different ways, cleaned with acetone or chemically etched. Single lap joints were manufactured using a brittle adhesive and a ductile adhesive to assess the influence of the type of adhesive. The joints were tested statically and under fatigue loading conditions. The patterns applied to the specimens consisted of a series of grooves, which were applied with 0°, 45° or 90° orientations (relative to the sides of the specimen). The different patterns were always compared to specimens without pattern. The main conclusion is that the patterns can increase the joint strength of non-treated substrates in the case of the brittle adhesive.