Fracture and post-fracture behaviour of glass and laminated glass structures

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The use of laminated glass as load bearing structure in buildings and engineering constructions gains increasing importance. Next to the use for extensive glass facades, laminated glass structures are applied as fall protection, walkable glass floor as well as essential load bearing component in form of beams and columns.The design and optimisation of novel structural glazing requires knowledge in material and structural behaviour. Especially, the understanding of the fracture mechanism in glass and the reliable prediction of the structural post-fracture behaviour of layered laminated glass is required. The construction and design of structural glazing is currently based on a conservative handling of approved design approaches. The Institute of Structural Mechanics and Design of TU Darmstadt has experience in manufacturing and experimental investigation of laminated glass structures for many years. The Institute for Structural Analysis of TU Dresden is focused on the development and implementation of numerical models. The combination of large experimental expertise and comprehensive experience in numerical models is a promising approach to the development of models to predict the fracture and post-fracture behaviour of laminated glass structures.Initially, the fracture mechanical behaviour of sole glass structures is investigated. The systematic experimental documentation of the fracture characteristics of thermally pre-stressed glass and the identification of the main influence parameters are in the focus of the investigation. Based on this, analytical and numerical models are developed, in order to describe and reliably predict the fracture process. The analytical model is founded on an energetic analysis of the whole structure for the prediction of the fracture pattern. The novel phasefield model shall be adopted for the description of the fracture configuration and the fracture process. At first, a continuum mechanical model is developed for the genesis of a micro-fragment, in order to understand and depict the fundamental fracture processes in glass. Subsequently, the formulation is transferred into a plate element and, this way, the simulation of the fracture process on the structural level is enabled. After documentation and modelling of the fracture processes in glass, the behaviour of the polymeric membrane, which is used as interlayer in laminated glass, is in the focus of the experimental investigation and the numerical modelling. Concluding, the combination of glass and polymer with respect to fracture is investigated. The final goal of the research project is the development of a systematic experimental data base for fracture and post-fracture characteristics of laminated glass structures as well as the development, implementation and application of a numerical concept for the description of the observed behaviour via the combination of crack evolution and material modelling.