Many materials in modern civil engineering applications, such as interlayers for laminated safety glass, are polymer-based. These materials are showing distinct viscoelastic (strain-rate) and temperature dependent behaviour. In literature, different mathematical representations of these phenomena exist. A common one is the 'Prony-series' representation, which is implemented in many state-of-the-art Finite-ElementAnalysis-Software to incorporate linear viscoelastic material behaviour. The Prony-parameters at a certain reference temperature can either be determined by relaxation or retardation experiments in the time domain or with a steady state oscillation in the frequency domain in the so called 'Dynamic Mechanical
This work deals with the prediction of glass breakage. A theoretical method based on linear elastic fracture mechanics (LEFM) merged with approaches from stochastic geometry is used to predict the 2Dmacro-scale fragmentation of glass. In order to predict the fragmentation of glass the 2D Voronoi tesselation of distributed points based on spatial point processes is used. However, for the distribution of the points influence parameters of the fracture structure are determined. The approach is based on two influencing parameters of fragment size δ and fracture intensity λ, which are described in this paper. The Fragment Size Parameter describes the minimum distance between the points and thus the size of a fragment. It is derived from the range of influence of the remaining elastic strain energy in a single fragment taking into account the LEFM based on the energy criterion of Griffith. It considers the extent of the initial elastic strain energy U 0 before fragmentation obtained from the residual stress as well as a ratio of the released energy η due to fragmentation. The Fracture Intensity Parameter describes the intensity of the fragment dis
The numerical treatment of the residual load-bearing behavior of laminated glasses (LG) in the post-fractured state is highly topical. Nevertheless, currently only few numerical approaches for an accurate representation of the experimentally observed behavior are existent. In order to model the characteristics of the load-bearing behavior of glass laminates in the post-fractured state, the behavior of the interlayer, the behavior of the glass fragments as well as the bonding between glass and interlayer need to be characterized correctly. This paper focuses on the modeling of the frictional contacts between the glass fragments itself. In order to allow for the calibration of failure criteria for the fractured glass particles, framed shear tests which are a common experimental technique in geomechanical testing to determine the shear strength of soils, are performed on glass fragments of different thicknesses and levels of thermal pre-stress. The test results are subsequently used to calibrate non-associated Mohr–Coulomb criteria, which are widely applied to the description of failure and frictional sliding of soils, to the experimental data of four distinct kinds of glass fragments. The obtained parameters of the Mohr–Coulomb models are in magnitude similar to the parameters of standard soils such as sand or gravel. The experimental data further show, that the Mohr–Coulomb model in general can be used to approximate the stress failure plane of the glass fragments but lacks for capturing correctly the plastic volumetric strains (dilation) in Finite Element modelling. Numerical investigations by the Finite Element method showed, that it is possible to reproduce experimental data by using Mohr–Coulomb plasticity models and hence the numerical models are validated for further investigations.
Spatial load bearing structures in the building sector are usually built with the help of aligned steel‐glass elements in the form of a net. The installed glass elements are flat and have a large glass thickness, in order to achieve sufficient plate stiffness. This implied a less economical use of materials. Nowadays, due to new manufacturing techniques it is possible to use resource saving materials, e.g. thin‐walled laminated safety glass (ttotal ≤ 5.38 mm). For this purpose, the thin‐walled laminated safety glass consists of thin glasses (t < 3 mm) and interlayer materials. The thin‐walled laminated safety glass is cold bent onto shaping frame girder elements (uniaxial or double curved) at the installation site with subsequent continuous supports. In general, this leads to a spatial load bearing capacity of the single element under pressure and suction loads. The process of cold bending is easily feasible due to the lower resetting effect of the thin‐walled laminate. For this case, a state of cold bending is activated in the glazing. With additional loading perpendicular to their shell level a state of loading is generated. To this, the load‐bearing capacity depends on many parameters (time‐ and temperature‐dependent material behaviour, geometry and supporting conditions). The aim of curved single elements is to achieve maximum geometric stiffness more specifically maximum static resistance ERd. For this reason, the influencing parameters were mathematically, numerically and experimentally investigated and discussed plus transferred to a design method for two exemplary cold bent structures (uniaxial or double curved).
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