A Preliminary Study on Fatigue Behavior of Aluminum Single-Lap Joints Subjected to Laser Surface Treatments

The study deals with the effects of laser surface treatments on the fatigue behavior of adhesive-bonded aluminum joints. Laser texturing, laser cleaning, and their combination are produced by adopting a 30 W nanosecond pulsed Yb:YAG laser. Parallel grooves, perpendicular to the load direction, varying in depth, width, and areal density are adopted as textured geometrical features. To assess the performance of laser treatments a central composite design (CCD) experimental plan is adopted to evaluate the apparent shear strength of single-lap joint test (ASTM D1002-10). Then, for the more promising treatment conditions, fatigue tests are carried out according to the ASTM D3166-99 standards, and cycles to failure are adopted to quantify the treatments. In addition, mechanical surface treatment (sandpaper polishing) is adopted as a reference treatment. Findings demonstrate that laser treatments significantly enhance the fatigue life of the joints (up to six times), offering a promising alternative to traditional mechanical methods.