Beitrag zur Betrachtung von Zweischeiben-Isolierverglasungen unter klimabedingten Drucklasten [Teil 1]

Contribution to the examination of double glazed units under climate-induced pressure loads — Part 1: Method of Calculation.

This article describes the development of a method for determining the maximum deflection of double glazed units under climate, wind and other area pressure loads. Starting from the Kirchhoff thin plate theory the well known series solution for simply on four sides supported plates is described. Following this it is shown, that the first element of the series solution for full area loads always overestimates the deflection that is calculated on the basis of many series elements. At the same time it is a sufficiently accurate solution for those plate measures which are relevant in buildings. This is followed by an insertion, with the help of which a simple method for calculating the temperature changes of the glazing under varying climatic boundary conditions is introduced. This is necessary, to determine the change of pressure due to the temperature induced gas expansion in the cavity of the insulating glass according to the ideal gas law. Also at this stage it can be shown that linearising the ideal gas law leads to acceptable losses of accuracy. After the integration of the plate solution and the ideal gas law, the final pressure states can easily be calculated by coupling the change of volume and the change of pressure. An exemplary calculation finally demonstrates the handling of the solution.
This is the first part of two publications; the second part describes the metrological validation of the algorithm.