Nondestructive Safety Evaluation of Thermally Tempered Glass

Zaccaria, Marco; Overend, Mauro

doi:10.1061/(asce)mt.1943-5533.0003086

Cited by 14 publications

(4 citation statements)

References 16 publications

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“…The depth of the compressive pre-stress region for the case of thermal strengthening is around 21% of the glass thickness. This relatively thick compressive pre-stress region reduces the risk of flaw penetration to the tensile region (Schwind et al 2020;Zaccaria and Overend 2020). However, the magnitude of the pre-compressive stress is significantly lower than that of chemically pre-stressed glass (Zaccaria et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Experimental strength characterisation of thin chemically pre-stressed glass based on laser-induced flaws

et al. 2022

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The strength of chemically pre-stressed glass depends on the depth of surface flaws and the value of the pre-stress. So far, some research has been conducted on this topic; however, there were always uncertainties regarding the flaw depth and the pre-stress profile. Consequently, this research characterises the pre-stress profile using experimental methods. The latter include measuring the depth of layer (DoL) and the surface compressive pre-stress (CS) with FSM-7000h and verifying the achieved DoL with the Na + and K + distribution through the thickness obtained from the SEM/EDS analysis. Results demonstrate that the amount of K decreases parabolically (secondorder) to a certain value and then remains constant. Based on this observation and some boundary conditions, the equation of the pre-stress profile was obtained for thin chemically pre-stressed aluminosilicate glass (Falcon®) with 8h and 24h processing durations in molten salt at 460 ˚C. A non-strengthened glass (NSG) was also used as a reference for comparison. Then, three artificial laser-induced flaws with accurately controlled depths is tested by means of a clamp bender. The results of the strength tests demonstrated very low deviations in the failure stress. It was shown that even when the depth of the flaw is higher than the DoL, which means that the flaw tip enters the zone with the pre-tensile stress, there is still considerable resistance from the surrounding intact area. Furthermore, it was confirmed that the pre-stress strain energy for 24h processing is larger than for 8h, leading to more fragmentation after failure under a similar loading condition. Finally, it was found that the fracture toughness is not constant through the pre-stressed glass thickness, and it is dependent on the pre-stress profile with the peak value at the glass surface.

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Section: Introductionmentioning

confidence: 99%

Experimental strength characterisation of thin chemically pre-stressed glass based on laser-induced flaws

et al. 2022

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“…The stresses formed by tempering treatment are distributed parabolically along the thickness direction. The absolute value of surface compressive stress is nearly half of the mid-plane tensile stress [30,35,36]. The strain energy stored inside is hence mainly related to the tempering level and glass thickness.…”

Section: Global Fragment Densitymentioning

confidence: 99%

Morphological characterization and reconstruction of fractured heat-treated glass

Zhu

Yang

Wang

et al. 2023

Journal of Non-Crystalline Solids

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“…The depth of the compressive layer reaches to about 20% of the wall thickness, what makes it less likely for microscopic surface flaws to penetrate into the tensile region. In the event of defect growth to beyond the compressive zone and catastrophic failure, the pronounced inner tension results in crack branching and crumbling into fragments with a size which is characteristic for the achieved stress profile, avoiding sharp and potentially harmful pieces of broken glass 10,11 …”

Section: Introductionmentioning

confidence: 99%

“…In the event of defect growth to beyond the compressive zone and catastrophic failure, the pronounced inner tension results in crack branching and crumbling into fragments with a size which is characteristic for the achieved stress profile, avoiding sharp and potentially harmful pieces of broken glass. 10,11 The most critical parameter in the thermal strengthening of glass products is the achievable rate of heat extraction, which determines the transient and residual stress profiles. In interplay with conductive heat transport from within the glass, it defines the minimum glass thickness for which a sufficiently large temperature gradient can still be generated and, thus, thermal strengthening is possible in practice.…”

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confidence: 99%

Thermal strengthening of low‐expansion glasses and thin‐walled glass products by ultra‐fast heat extraction

Sajzew

Wondraczek

2021

J. Am. Ceram. Soc.

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Mechanical performance and consumer product safety have been major drivers for glass research and innovation. Commodity glass materials are brittle and, thus, their mechanical performance is extremely sensitive to the presence of microscopic flaws and defects at their surface: the extent by which surface flaws reduce the practical strength of glass products exceeds the effect of any optimization in glass composition by several orders of magnitude. 1 Strength-reducing flaws are created already during glass manufacture 2,3 : the intrinsic strength levels which are expected from theoretical considerations can be approached experimentally only on carefully drawn glass fibers which are basically free of microscopic defects. 4,5 For other types of glass products, processes such as acid-or fire-polishing are often applied in order to create defect-free surfaces. Such post-processing does not only reduce the presence of surface defects or flaws on pristine glass articles, but may also lead to a more persistent enhancement of product durability by generating surface gradients in chemical composition, mass density and residual stress.The most prominent post-processing methodologies for enhancing the strength of glass products rely on diffusive

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Nondestructive Safety Evaluation of Thermally Tempered Glass

Cited by 14 publications

References 16 publications

Experimental strength characterisation of thin chemically pre-stressed glass based on laser-induced flaws

Experimental strength characterisation of thin chemically pre-stressed glass based on laser-induced flaws

Morphological characterization and reconstruction of fractured heat-treated glass

Thermal strengthening of low‐expansion glasses and thin‐walled glass products by ultra‐fast heat extraction

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