Experimental and numerical assessment of the effect of transverse reinforcing of AL-GFRP single lap adhesive joint using Z-pins under tensile loading

In this study, the effect of z-pins on the strength of the single-lap adhesive joint of GFRP composite-aluminum has been investigated. The joint consists of Al 7075T6 and Glass/Epoxy composite as adherends. Araldite 2015 A/B has been used as the adhesive along with four, six and eight steel pins that reinforced the joints in the z-direction. The stress analysis of the joints was done experimentally using tensile testing and numerically by the cohesive zone model (CZM) for progressive damage in commercial finite element software ABAQUS with the objective of reproducing the experimental results and better understanding of the failure mechanisms. The numerical results show that the maximum shear and peel stresses occur at the interface of the adhesive-composite in the joint. Also, local deformation was observed around the z-pin holes, thereby reducing the joint rigidity. It is concluded that there is a maximum number of z-pins beyond which the strength of the joint starts to decrease. This optimum number includes six z-pins in which the ultimate load of the joint increases by 19.5%. Finally, the numerical analysis has shown to have good agreement with the experimental results, indicating a promising model that can be used for further investigations for these joints.