An End-Loaded Shear Joint (ELSJ) Specimen to Measure the Critical Energy Release Rate in Mode II of Tough, Structural Adhesive Joints

This paper introduces a newly developed specimen type, which is used to measure the critical energy release rate of tough, structural adhesives loaded in shear. This End-Loaded Shear Joint (ELSJ) specimen is loaded until a shear crack propagates through the adhesive layer. When the crack propagation is stopped, by unloading the specimen, the critical energy release rate in mode II, GIIc, can be obtained by correlating the energy dissipated during the test and the measured crack area on the fracture surface of the specimen. The paper presents the dimensions of the ELSJ specimen, the corresponding test setup and the evaluation method used to obtain GIIc. An overview of the advantages and the limitations of the new specimen type shows the need for its development and improvement when compared to some state of the art experiments. The first results of ELSJ tests are shown and discussed, using the crash-optimized structural adhesive - Henkel Terokal 5077. The experimental results presented, focus on thin adhesive layers and quasi-static test velocities.