Optimisation of interlocking microstructured adhesive joints via finite element modelling, design of experiments and 3D printing

The potential to optimise the performance of microstructured joints based on mechanically interlocking adherends is investigated via experimental testing and finite element (FE) analysis. The microstructured joints were realised via imprint lithography and injection moulding. FE modelling indicated that, a frictional interface (i.e. no adhesive) was sufficient to generate joint load capacities within about 7% of the experimental values. This result indicates that mechanical interlocking (via feature bending) accounts for most of the tangential load carrying capacity of the joints – opening up the possibility of adhesive-less joints. The FE model was then used for a design of experiments analysis to identify key relationships between interlocking geometric parameters and mechanical performance, with a three-way ANOVA analysis employed to determine relative importance. Feature aspect ratio was found to be the key parameter defining performance. Energy absorption increased with feature aspect ratio while load capacity peaked at an aspect ratio of 1 making square features the best compromise for load capacity and toughness. Finally, the viability of a more cost-effective, SLA-based 3D printing approach is demonstrated for fabricating the interlocking joints, whereby the potential to tailor for optimised hybrid performance was studied by varying feature geometry horizontally along the joint.