Influence of Bondline Thickness on the Performance of Adhesive Joints Under Ballistic Peel Impact

Abstract

Abstract As structural adhesive technology advances, adhesive joints provide attractive advantages over conventional fastening methods. Since welding, riveting, and bolting may cause nonuniform stress distribution across the joint, and in many cases cannot be used to bond dissimilar materials such as composites to metals, adhesive joining may be considered as an alternative joining method. It is well known that the geometry of adhesive joints as well as their material properties and the adhesive thickness may affect their performance. In this study, an adhesive joint consisting of an aluminum back plate and a patch bonded by an epoxy is employed to investigate the influence of the bond thickness on the performance of adhesive joints under predominantly Mode I ballistic impact. A pressure gas gun is used for the dynamic test. High speed camera (Phantom V710) was used to record specimen behavior under ballistic peel impact tests. Frame rate of the high-speed camera to capture impacts was kept at 120,000 per second. The effect of bondline thicknesses (i.e., 0.005” (0.127 mm), 0.01” (0.254 mm), 0.015” (0.381 mm) on the adhesive joint performance were investigated. The results indicate that the adhesive joint with 0.01” mm bondline thickness performs better than those with 0.005” and 0.015” adhesive thickness. In addition to the experimental work, Finite Element Analysis is carried out to determine the mechanical properties of the joints by an inverse problem-solving technique.