Mode I Fracture Energy of Adhesive Joints Bonded with Adhesiveswith Different Characteristics Under Quasi-static and Impact Loading

Abstract

Double cantilever beam joints were manufactured from spring steel substrates bonded together using a twopartepoxy adhesive, a two-component type second-generation acrylic adhesive, and a one-part polyurethaneadhesive. Rheological behavior of the adhesives was measured with a dynamic mechanical analyzer. Mode Ifracture behavior of the joints was investigated with a tensile test machine and a falling-wedge impact test machinechanging opening speeds from 8.33 × 10^-5 m/s to about 1.9 m/s. Although stable fracture was observedfor the epoxy and polyurethane adhesives under the tested conditions, unstable（i.e. stick-slip） fracture wasobserved for the acrylic adhesive when increasing the opening speed. Adhesive fracture energy, G_IC, was estimatedusing several methods. Different dynamic dependency of the fracture energy was observed dependingon the type of adhesive, and correlation between the change of fracture energy against opening speed and thechange of dynamic loss tangent against temperature was suggested.