Abstract of: Sensitivity analysis for the determination of the interlayer shear modulus in laminated glass using a torsional test

Abstract

Polymeric interlayers used in laminated glass show viscoelastic material behaviour. Therefore, the precise design of laminated glass structures is dependent on temperature and the load duration. For the determination of the abovementioned material behaviour of the interlayers different small and big scale test setups exist. One of these tests is the torsional test in which the shear modulus of the interlayer can be calculated from measured data during a relaxation test. In this test, a laminated glass plate is conditioned at a certain temperature of interest and then isothermally twisted to a specific angle, thereby the resulting torsional moment at the support is measured over a time span. With this data, it is possible to calculate the corresponding shear modulus of the interlayer. There are a lot of parameters and boundary conditions with potential influence on the test and the results (e.g. accuracy of the thickness of the glass plates and interlayer, accuracy of the twist-angle, clamping of the laminated glass). Based on already conducted torsional tests at the ‘University of German Armed Forces Munich’ a Finite Element Model was implemented. In a sensitivity analysis (Finite-Element-Analysis using ANSYS® V17.2) the influences and the interdependencies of the parameters and boundary conditions of the test setup were determined. The results of the analyses can be used to get an understanding of the significance of the measured and calculated values for the shear modulus of the interlayer using a torsional test. Furthermore, the results can help to optimize the torsional test. Moreover, the torsional test results were compared to small scale test results from a Dynamical Mechanical Thermal Analysis, which exposes small scale test specimen to a steady state oscillation at different frequencies and temperatures.