GLASS-METAL JOINTS BONDED WITH UV- AND LIGHT-CURING ACRYLATES

摘要

Glass construction components are conventionally connected by established joint mechanisms such as clamping and bolting. By contrast, bonded joints offer a unique opportunity to connect glass in the form of a material-to-material bond that permits a homogeneous load transfer while simultaneously reducing the local stress peaks in the contact area. The use of UV- and light-curing acrylates is preferred. Such adhesives are clear and colourless, and thus achieve an even greater degree of transparency - congruent with the growing desire for lightweight constructions. Short curing times - no more than a few minutes - result in quick production with minimal downtime within the overall process. Subsequent processes can begin immediately once bonding is complete. The advantages of acrylates can be compared to the characteristics and properties of the silicone adhesives that have been widely approved by building authorities for specific facade applications (structural sealant glazing systems, SSGS). The material behaviour and mechanical properties of selected acrylates were assessed by intensive testing to qualify such an innovative adhesive system for structural use. Comprehensive testing of glass-metal bonds provided a basis from which it was possible to determine the bond strength while permitting a closer look at the fracture pattern, caused in most cases by adhesion failure. Adhesives are analysed both generally as bulk materials and in specific applications where they serve as joints between glass and metal. The use of dumb-bell specimens is recommended for analysing the material behaviour under a variety of influential factors such as temperature and testing rate. A cohesive failure appears. The bonded joints of test specimens provide an opportunity to examine the interaction between the adhesive and the materials to which it is applied. The examination of the delamination is part of the approach to avoid failure and to design an adhesive joint for loadbearing applications. A bonded glass construction, designed for use as a safety barrier, was analysed using a finite element program. In this case, the effects of the alterable geometry of the glued joint and the material properties are evident. The results are interesting; in particular, the thickness and length of the glued joint have a huge effect on the creation of a homogeneous stress state.