Investigation of Bonded Connections with Silicone under Shear Loading

In façade applications, structural sealant glazing systems with a soft adhesive like silicones show a number of advantages especially regarding brittle adherends like glass sheets, as stress concentrations in the adherends are avoided due to the large bonding area and the uniform load transfer. The application guideline for structural sealant glazing systems (European Technical Application Guideline ETAG 002) defines a simplified design concept for the silicone sealant, leading to high safety factors and restrictions in use. The material behaviour of the silicone sealant can be more accurately described using the Finite Element Method and hyperelastic material laws, but the results for the stresses at the edge area for a shear dominated loading are highly mesh dependent, due to the presence of a singularity and thus hampering the assessment of the realistic stress distribution. In this paper, shear tests on bonded connections with silicone, referring to the ETAG 002, are presented. Beside the overlap length and adhesive thickness of the specimen prescribed by the standard, two more overlap lengths and thicknesses are tested. For the experimental investigations, the force-deformation behaviour and the failure initiation, observed at the edge area, are recorded. Unlike for the adhesive length, an influence of the specimen thickness on the failure shear strain could be observed and predicted by the numerical simulations. A clear difference between the maximum load and the load at failure initiation was observed.