A powerful new tool for testing adhesives in situ

The thick-adherend tensile-shear test of adhesive technology is Improved in the experimental parr and supplemented with a new computer-aided evaluation method. Stepped substrates ensure a more uniform stress state by increasing the stiffness of the assembly. In order to minimize the influence of the adherend deformation, which is taken into account by a finite element calculation, the total displacement of the joint was measured directly at the overlap zone. For this purpose, two extensometers with strain gages were attached to each side of the specimen at three reference points. In this way, realistic shear data were obtained from the determined stress-strain diagrams. The evaluation procedure was also improved by developing a numerical test simulation technique that allows the computation of Young's modulus. Steel substrates and an anaerobic adhesive were used. The influences of both the test temperature and the bond gap on the mechanical properties: of the joint were investigated.