Influence of material and geometry parameters on the adhesive stress and strength of anchor bolts for thick FRP laminates

Adhesive bonded anchor bolts have the potential to apply high local loads to fiber reinforced polymer (FRP) composites by standard screw connections with little manufacturing effort. However, because of different geometry and material properties the stress distribution within the adhesive layer varies from conventional lap joints. In this study the influence of these properties on the stress distribution within the adhesive and the load bearing capacity of the anchor bolt are analyzed. A numerical parametric study is performed to determine the influence of substrate geometry parameters as well as adhesive and laminate material properties on the stress distribution. The results show that there are characteristic effects on the adhesive stresses of anchor bolts in FRP laminates such as: the non-homogeneous distribution along the circumference, the influence of the in-plane shear stiffness G ₁₂ of the laminate and the interaction between the overlap length and the cross section. In addition, the impact of geometry parameters on the load bearing capacity of the joint with a glass fiber-reinforced polymer (GFRP) laminate under tensile load is experimentally determined. Damage types of the joint are described and failure modes defined. In case of the used ductile adhesive the load bearing capacity shows to be directly proportional to the anchorage length. Further, the results determined a dependence of the failure mode and the load bearing capacity on the cross section of the laminate.