Relationship between 3D surface roughness parameters and load capacity of adhesive joints after shot peening

The aim of the article was to investigate whether 3D roughness parameters can be used to assess the strengthening treatment and to predict the load capacity of lap adhesive joints subjected to shot peening. The analyzes were carried out for single-lap adhesive joints made of EN AW-2024-T3 aluminum alloy, whose overlaps were shot peened for 60 to 180 s using balls with a diameter of 0.5 to 1.5 mm with a compressed air pressure of 0.3 to 0.5 MPa. As a result of the regression and correlation analysis, it was found that within the adopted range of input parameters variability, the load capacity of adhesive joints subjected to shot peening is most closely related to the roughness parameter Sdr. It has been shown that increasing the value of the Sdr parameter contributes to increasing the load capacity of adhesive joints. A mathematical model describing the impact of treatment time, balls diameter and compressed air pressure on the value of the Sdr parameter was also built. The model was built in accordance with the the Hartley's PS/DS-P:Ha3 plan methodology. The obtained results allow to conclude that the Sdr parameter can be used to predict the load capacity of adhesive joints after shot peening and to assess the strengthening treatment (within the assumed range of input parameters variability). Additionaly, the simplicity and low cost of roughness measurements justify the use of this method in industrial purposes.