Effect of loading rate, surface flaw length and orientation on strength of laser-modified architectural glass

The strength of architectural glass (soda-lime silica) is highly dependent on surface flaws generated during production, handling and service life. Fracture mechanical investigation of glass, however, is challenging due to e.g. the randomness of flaw size, flaw orientation and quality. Generation of radial and median cracks is inevitable while using a mechanical indenter with direct contact. These undesirable effects, along with uncertainty about the groove’s depth and geometry, degrade the accuracy of results and underline the need for a more reliable tool. Consequently, this contribution focuses instead on the application of ultra-short laser as a non-contact tool, which recently has proved to be a promising solution because of its precision, high speed, and repeatability. Here, artificial grooves with a well-controlled depth are realized on the surface of soda-lime silica glass to investigate the effects of loading rate, flaw size and flaw orientation on the glass strength. Four- point bending tests are performed to assess the failure loads. The method manages to capture the results with a very low standard deviation of the failure stress (approximately 1 MPa), eliminating the need for using large series of specimens.