Joint strength optimization of single lap adhesive joints by surface patterning

The objective of this work is to investigate the influence of macro-pattering and present its benefits compared to conventional surface preparation methods for adhesive bonding, regarding the eco-friendliness, strength and repeatability of the process. In particular, three different angles of 60°, 90° and 120° patterns were conceptualized and produced by wire cutting process on aluminium alloy surface. The statistical investigation was carried out on patterns produced for single lap joints regarding their influence on the joint strength performance. The statistical analysis was related to geometrical parameters of the adhesive bond and the surface pattering. To quantify the influence of the substrate angular pattering, the type of adhesive, the adhesive thickness, the adherend thickness and the overlap length were varied. The design of experiments technique of Taguchi was used. An experimental matrix of 18 different tests was developed and each test was repeated twice. The influence of the five aforementioned variables was assessed using the statistical software Minitab 17. Five parameters with different variability levels were considered. The signal-to-noise ratios and analysis of variance ANOVA were applied to determine the optimum parameter combinations. The results showed that angles of pattern of 120° and 60° provided for higher shear strength of ductile 2015 and brittle AV138 adhesives.