Determination of impact tensile properties of structural epoxy adhesive butt joints using a hat-shaped specimen

Abstract
The impact tensile properties of structural epoxy adhesive butt joints are determined with a modified version of the split Hopkinson pressure bar using a hat-shaped joint specimen. A typical two-component structural epoxy adhesive and two different adherend materials (Al alloy 7075-T6 and 99% pure titanium) are used in the adhesion tests. The impact joint tensile strength is evaluated from the applied tensile load history at failure. The corresponding static joint tensile strength is measured with an Instron testing machine using joint specimens of the same geometry as those used in the impact tests. It is demonstrated that the joint tensile strength increases definitely with increasing loading rate up to the order of 106 MPa/s, and decreases with increasing adhesive layer thickness up to nearly 180 m, depending on the adherend materials.