Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-45703 Posterpräsentation Kiefer, P. Statistical analysis of Vickers induced subcritical crack growth in soda-lime silicate glasses Studies on Vickers induced subcritical crack growth are controversially discussed since the stresses that drive the crack growth are distributed three dimensionally within the material and cannot be retraced by available methods. Hence, empirical approaches are used to calculate mechanical material parameters such as the stress intensity factor KI. However, the results of these approaches show large deviations from those measured by standardized techniques such as double cantilever beam (DCB) or double cleavage drilled compression (DCDC). Yet, small specimen sizes and low specimen quantities can prevent the execution of DCB and DCDC measurements. Here we present an approach that is based on a statistical analysis of Vickers induced radial cracks. For this purpose more than 150 single radial cracks were analyzed. The cracks were generated in a commercial soda-lime silicate glass. The experiments were performed in a glovebox purged with dry nitrogen gas to minimize the influence of atmospheric water on crack growth. The temporally resolved evolution of the radial cracks was monitored in-situ using an inverted microscope equipped with a camera system directly below the Vickers indenter. An automated image analysis software was used to determine the crack length over time. The data show that the crack propagation and thereby the crack velocities are not uniformly but statistically distributed. These findings allow, using the statistical mean value of the distributions in combination with DCB data, a precise formulation of KI for each measured crack length. 2018 92nd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meetings of the Czech Glass Society & the Slovak Glass Society Bayreuth, Germany 28.05.2018 30.05.2018 2018-08-15 OPUS4-45704 Posterpräsentation Kiefer, P. Subcritical crack growth in water bearing soda-lime silicate glasses The presence of water in the surrounding atmosphere of a propagating crack has a major influence on the subcritical crack growth. While these external phenomena are well understood, there is still a lack of knowledge on the influence of structurally bound water on crack propagation. Thus, our recent study aims on the analysis of crack propagation in water bearing soda-lime silicate glasses with up to 8 wt.% water. The samples were synthesized in an internally heated pressure vessel at 0.5 GPa. Since this preparation route limits the sample sizes, standard test geometries allowing for the determination of stress intensity factors, such as double cantilever beam, are not feasible. Thus, radial cracks in the hydrous glasses were initiated by Vickers indentation and crack growth was simultaneously captured with a camera system. An automated image analysis algorithm was used for the analysis of the crack length of each single video frame. To minimize influences by atmospheric water, all experiments were conducted in a glovebox purged with dry N2. About 150 cracks per glass composition were analyzed to provide statistical significance of the Vickers-induced SCCG. The results show that structurally bound water has a major influence on SCCG by means of crack lengths, growth rates and time of crack initiation. 2018 92nd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meetings of the Czech Glass Society & the Slovak Glass Society Bayreuth, Germany 28.05.2018 30.05.2018 2018-08-15 OPUS4-45707 Vortrag Kiefer, P. Statistical analysis of subcritical crack growth in water bearing soda-lime silicate glasses The talk was given at the PNCS-ESG 2018 in Saint Malo and summarizes the actual findings about Vickers induced crack growth in water bearing soda-lime silicate glasses. 2018 15th International Conference on the Physics of Non-Crystalline Solids & 14th European Society of Glass Conference Saint Malo, France 09.07.2018 13.07.2018 2018-08-15 OPUS4-48343 Posterpräsentation Kiefer, P. Subcritical crack growth in water bearing soda-aluminosilicate glasses The subcritical crack growth in water bearing soda-aluminosilicate glasses is compared to the crack growth in a commercial soda-lime silicate glass. The water speciation is shown for comparison of water species in the material. Differences will be discussed in the poster session. 2019 Glastechnische Tagung 2019 Nürnberg, Germany 13.05.2019 15.05.2019 2019-07-02