Digital full-field photoelasticity of tempered architectural glass: A review

Dix, Steffen; Schüler, Christian; Kolling, Stefan

doi:10.1016/j.optlaseng.2022.106998

Cited by 18 publications

(3 citation statements)

References 68 publications

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“…There are several methods for determining the pre-stress distribution such as the scattered light method and RGB photoelasticity (Dix, Schuler and Kolling 2022;Laurs et al 2019). The seconddegree polynomial distribution was assumed for thermally toughened glass in which the pre-stress is produced by quenching of hot glass (Nielsen et al 2021).…”

Section: Pre-stress Distributionmentioning

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: Pre-stress Distributionmentioning

confidence: 99%

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

et al. 2022

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“…Retardation R determines the color of iridescent patterns because R and λ show a periodic function relationship with interference light intensity I according to equation (1), and their correspondence can be obtained according to Michel-Lévy interference color chart. 33 As R increases, the iridescent patterns successively get black zero-order fringes, gray, white, orange, and red first-order fringes, blue, green, orange, and red second-order fringes, and third-and above-order fringes. The lower order fringes with black, white, and gray appear at the lower retardation, and in contrast, colorful higher order fringes appear at the higher retardation.…”

Section: Optical Characteristics Affecting the Color And Brightness O...mentioning

confidence: 97%

Influence mechanism of injection process parameters on iridescent pattern defects on optical molded parts

Yuan,

Qiu

2023

J of Applied Polymer Sci

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Iridescent patterns are insufferable molding defects during mass manufacturing of polymer optic devices by using injection molding (IM) technique and seriously affect the appearance and imaging performance of parts. However, at present, the research on the factors affecting iridescent pattern defects is lacking, resulting in the difficulty of obtaining effective methods to weaken iridescent pattern defects. This article aims to clarify the correlation mechanism between injection process parameters and iridescent patterns and provide a theoretical basis for reducing iridescent pattern defects. Based on the process characteristics of IM and the optical mechanism of iridescent patterns, the correlation between iridescent patterns and influencing factors such as optical characteristics and the material structure is established. The influence mechanism of process parameters on iridescent patterns is further clarified by experiments. The results show the iridescent pattern color is related to the retardation, while the iridescent pattern brightness is affected by the retardation and transmittance. Process parameters change the retardation and transmittance by varying factors such as the thickness, birefringence, and crystallinity. Higher mold temperature, reasonable melt temperature, injection speed, and holding pressure are conducive to reducing the colorful fringe area and iridescent pattern brightness, thereby weakening the iridescent patterns on the part.

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“…Despite the continuous glass industry efforts in optimising the process (Dix 2022, Monnoyer 2008, Mikkonen 2017), the tempering unintentionally produces minor differences in residual stress distribution in the glass panel due to non-uniform heat exposure and transfer making the glass birefringent. Due to its photo-elasticity, glass shows optical anisotropic behaviour since the optical index locally varies according to the different embedded stress (Dix 2022, Illguth 2015. This leads to birefringence phenomena which are more or less visible according to the observation conditions.…”

Section: Introductionmentioning

confidence: 99%

Coatings Sensitivity to the Quench Marks

Maccariello

Hivet

2022

CGC

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During tempering process, the non-homogenous heating or rapid cooling can induce localized strain in the glass leading to birefringence (or optical anisotropy) phenomenon, a result of the photoelastic effect. Since transmission and reflection coefficients of interfaces at high angles can be quite different with the polarization, inhomogeneous birefringence may manifest as peculiar geometric patterns of bright or darkish shadows or iridescence effects in given polarized observation conditions. The patterns appearance may be at the origin of dispute between the client and the glass manufacturer. Each party may have a different perception, how strong the anisotropies are and what is permissible. With the use of an in-line scanner for the optical retardation, it is possible to control and optimise the tempering process homogeneity and thus reduce the visibility of the patterns. However, the presence of low emissivity coatings on the façades windows can alter the visibility of the quench marks: depending on the coating nature, the quench pattern visibility can be magnified or reduced. Here, we show the calculation of σQM, as a parameter representing the coating sensitivity to quench marks, i.e., the capability of a coating to reveal or hinder the iridescence pattern of tempered glass. Thanks to the angular measurements of the transmission and reflection in s and p polarization we compute the quench mark sensitivity by estimating a color contrast gradient with regard to the phase delay.

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Digital full-field photoelasticity of tempered architectural glass: A review

Cited by 18 publications

References 68 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

Influence mechanism of injection process parameters on iridescent pattern defects on optical molded parts

Coatings Sensitivity to the Quench Marks

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