Compressive zone depth of thermally tempered glass

Nielsen, Jens Henrik; Thiele, K.; Schneider, Jens; Meyland, Martin J.

doi:10.1016/j.conbuildmat.2021.125238

Cited by 20 publications

(9 citation statements)

References 12 publications

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“…1. The depth of the compressive zone is both analytically and experimentally found to be reasonably good approximated by 21 % of the glass thickness (Nielsen et al 2021). Failure of thermally tempered glass may be initiated as soon as the compressive surface stress that prevents flaws from opening (i.e.…”

Section: Introductionmentioning

confidence: 84%

High strain rate characterisation of soda-lime-silica glass and the effect of residual stresses

Meyland

Nielsen

2022

Preprint

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A ring-on-ring test configuration for the equibiaxial flexural testing of flat samples was developed and integrated into a novel modified split-Hopkinson pressure bar (SHPB) setup. The established modifications enabled the application of high-speed cameras for fracture assessment and non-contact displacement measurements using stereo digital image correlation (stereo-DIC). In the present paper, this setup was utilised to characterise the flexural surface strength and stiffness (Young's modulus) of circular, as-received soda-lime-silica glass samples at high strain rates. The effect of residual stresses was also studied by including thermally tempered glass samples divided into four residual stress groups. Despite the frequent application of glass products in the built environment, often post-processed into tempered or laminated glass, these investigations are still rare and thus highly demanded when designing for extreme events such as extreme weather, ballistic impacts, or blast loads. A total of 315 samples were tested at a quasi-static and a dynamic loading rate ranging from 2.0 MPa s -1 to 4.2·10 6 MPa s -1 . It was found that the flexural strength of the glass across residual stress groups was strongly dependent on the applied dynamic loading rate, while the residual stresses themselves showed no significant effect on the loading rate dependency. At the dynamic loading, the strength increased between 60 and 86 %. Within the two tested loading rates, strength increased expectedly with compressive surface stress. From the stereo-DIC displacement measurements, no change in Young's modulus with loading rate was observed.

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Section: Introductionmentioning

confidence: 84%

High strain rate characterisation of soda-lime-silica glass and the effect of residual stresses

Meyland

Nielsen

2022

Preprint

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“…Bisherige Untersuchungen zu Vorspannungsprofilen sind u. a. die in [6] dargestellten Ergebnisse an den Kanten vorgespannter Gläser vor und nach dem Schleifen sowie die in [7] beschriebenen Resultate lokaler Untersuchungen der Oberflächendruckspannungen aufgrund der Abkühlung mit Düsen. Vor kurzem hat Nielsen et al in [8] Untersuchungen zur Druckzonentiefe in thermisch vorgespanntem Glas veröffentlicht. Diese Untersuchung zeigt eine Abhängigkeit der Druckzonentiefe von der Glasdicke.…”

Section: Einleitung Und Motivationunclassified

“…Schematische Darstellung des thermischen Vorspannprozesses mit Definition der oberen Glasoberfläche ("top") sowie der unteren Glasoberfläche ("bot") (© K. Thiele, ISM+D, nach[5]) Schematische Darstellung der Eigen spannungsverteilung im thermisch vorgespannten Glas (© K. Thiele, ISM+D, nach[8]) Schematische Darstellung des Streulicht-Polariskop (SCALP) mit Definition der Koordinatenachsen (© K. Thiele, ISM+D, nach[9])…”

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Statistische Charakterisierung der Druckzonentiefe vorgespannter Gläser

et al. 2022

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Infolge variierender Produktionsbedingungen erfolgt der thermische Vorspannprozess von Gläsern nicht vollständig homogen. Daraus entstehen lokale Unterschiede in den Eigenspannungen. Um die statistischen Verteilungen von charakterisierenden Größen des Eigenspannungsprofils in thermisch vorgespanntem Flachglas zu bestimmen, wurden mehr als 100 Proben mit einem Streulicht‐Polariskop (SCALP) untersucht. Die Messungen wurden an zuvor definierten Stellen in drei Richtungen an beiden Oberflächen der Probekörper durchgeführt. Dies ermöglicht die quantitative Auswertung und Kalibrierung statistischer Modelle der Druckzonentiefe sowie der Homogenität der Vorspannungsprofile. Statistical characterization of compression zone depth in pre‐stressed glasses. Due to varying production conditions, the thermal tempering process of glass is not fully homogeneous. This results in local differences in the residual stresses. In order to determine the statistical distributions of characterizing quantities of the residual stress profile in thermally toughened flat glass, more than 100 samples were examined with a scattered light polariscope (SCALP). The samples were examined at previously defined locations from both surfaces in three directions with respect to the pre‐stress profiles. This allows the quantitative evaluation and calibration of statistical models of the compression zone depth and the homogeneity of the prestress profiles.

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“…The magnitude of the surface stress is approximately twice the tensile stress, (2𝜎 m = |𝜎 s |). The zero stress level is at a depth of approximately 21% of the thickness, ℎ, from the surface, known as the compressive zone depth [21]. The surface flaws then are in a permanent state of compression by the compressive residual stress at the surface, which has to be exceeded by externally imposed stresses due to loadings before failure and fracture of the glass pane can occur [10,22].…”

Section: Background On Thermally Pre-stressed Glassmentioning

confidence: 99%