Testing Procedure and the Effect of Testing Machinery on Four‐Point Bending of Curved Glass

Abstract

ABSTRACTThe paper presents a method to determine the bending strength of thermally curved glass with the four‐point bending test, which was developed during the research project PRÜFgbGLAS at Technische Universität Dresden. The test procedure as well as the calculative evaluation closely refers to the EN 1288‐3, which defines the determination of the bending strength of flat glass. However, with curved glass specimens, parameters like the bending radius or the chord length, as well as a practical realisation in the industry have to be taken into account. During the project over 360 specimens were tested with recording the strain at the tensions side and the input force. The examined glass thickness ranged from 3 mm to 12 mm and the bending radii from 400 mm to 2000 mm. Besides, four specimens were tested non‐destructively on different testing machineries in collaboration with four specialists from the glass bending industry. This article gives a practical overview over the application of the new aspects to perform a four‐point bending test on a thermally curved glass specimen. It describes the specimen measurement and the modification of the test rig for testing small bending radii. Further, it presents the results of the additional tests on different testing machineries and discuss the deviation of results, which may occur with the new procedure.