Parametric analysis of failure load of single lap adhesive joints using the response surface method

Over the past few decades, the application of adhesively bonded joints has increasingly expanded in aerospace and aeronautical industries. Single lap joints (SLJs) are the most famous types which are more considered by researchers. However, because of the multiple effective geometrical features and their interaction, statistical analysis would be inevitable. In this paper, the interaction effects of different geometrical features on the failure load of SLJs are investigated using the statistical response surface methodology (RSM). To achieve this, the RSM was used to design the experiments. The design contains four geometrical features with five level. In this study, the overlap length, the free length, the adhesive thickness and the substrate thickness of the joints are considered as the variables. Aluminum-Epoxy SLJs with various geometries are prepared and tested under tensile loading. The effects of the four variables on the experimentally failure loads are completely investigated. It is found that failure loads increase by increasing the overlap length and substrate thickness and decrease by rising the free length and adhesive thickness. According to the result, the overlap length is the most significant parameter on the failure load of a SLJ. In addition, this variable has a considerable interactions with adhesive thickness. The effect of other variables on the response are more considerable at higher overlap lengths.