“…On the basis of equations (13) and (14), a method for measuring residual stress in axisymmetric glass articles has been elaborated [18,24]. In this method the stresses are approximated by polynomials.…”
Section: Integrated Photoelasticity In Case Of Weak Birefringencementioning
confidence: 99%
“…Since integrated photoelasticity is mostly used by measuring residual stress in glass [18,24], we consider complete stress analysis in this case. We may use the equilibrium equation @s r @r þ s r À s q r þ @t rz @z ¼ 0; ð23Þ which in a discrete form can be written as…”
Section: Determination Of Other Stress Componentsmentioning
confidence: 99%
“…Photoelastic measurements were carried out with a computercontrolled polariscope [24] using the phase-stepping method [29]. The version of the phase-stepping method, described in [29], permits to determine besides the parameter of the isoclinic and the optical retardation also the direction of the first principal stress.…”
Section: Stresses Near the Neck Seal Of A Crt Glass Bulbmentioning
By measuring stresses in cylinders with no stress gradient in axial direction, the cross-section of the cylinder may be considered as consisting of concentric rings in each of which the stresses are constant. Axial stress distribution in the cylinder is determined stepwise starting with the outermost ring (the so-called onion-peeling method). This paper generalizes the onion-peeling method for the case of axisymmetric stress distributions when stress gradient in the axial direction is present. Measurement of the integrated isoclinic and optical retardation is carried out in two parallel sections which are perpendicular to the specimen axis, Δz apart from each other. The distributions of the axial stress and shear stress are determined directly from the measurement data, using linear approximation of integrated photoelasticity. Other stress components are determined using the equilibrium equation and the compatibility equation (if stresses are due to external loads) or using the generalized sum rule (if residual stresses in glass are measured). The method is less sensitive to measurement errors than the Abel inversion. In comparison with the polynomial approximation of the stress distributions, the onion-peeling method gives more adequate results if stress distribution is not smooth. The paper is illustrated with several applications.
“…On the basis of equations (13) and (14), a method for measuring residual stress in axisymmetric glass articles has been elaborated [18,24]. In this method the stresses are approximated by polynomials.…”
Section: Integrated Photoelasticity In Case Of Weak Birefringencementioning
confidence: 99%
“…Since integrated photoelasticity is mostly used by measuring residual stress in glass [18,24], we consider complete stress analysis in this case. We may use the equilibrium equation @s r @r þ s r À s q r þ @t rz @z ¼ 0; ð23Þ which in a discrete form can be written as…”
Section: Determination Of Other Stress Componentsmentioning
confidence: 99%
“…Photoelastic measurements were carried out with a computercontrolled polariscope [24] using the phase-stepping method [29]. The version of the phase-stepping method, described in [29], permits to determine besides the parameter of the isoclinic and the optical retardation also the direction of the first principal stress.…”
Section: Stresses Near the Neck Seal Of A Crt Glass Bulbmentioning
By measuring stresses in cylinders with no stress gradient in axial direction, the cross-section of the cylinder may be considered as consisting of concentric rings in each of which the stresses are constant. Axial stress distribution in the cylinder is determined stepwise starting with the outermost ring (the so-called onion-peeling method). This paper generalizes the onion-peeling method for the case of axisymmetric stress distributions when stress gradient in the axial direction is present. Measurement of the integrated isoclinic and optical retardation is carried out in two parallel sections which are perpendicular to the specimen axis, Δz apart from each other. The distributions of the axial stress and shear stress are determined directly from the measurement data, using linear approximation of integrated photoelasticity. Other stress components are determined using the equilibrium equation and the compatibility equation (if stresses are due to external loads) or using the generalized sum rule (if residual stresses in glass are measured). The method is less sensitive to measurement errors than the Abel inversion. In comparison with the polynomial approximation of the stress distributions, the onion-peeling method gives more adequate results if stress distribution is not smooth. The paper is illustrated with several applications.
“…Equation (13) can be used to calculate the vector S (α,β) (t) at time t n+1 based on its value at time t n and increment Δe n .…”
Section: Mechanics Of Thin Layersmentioning
confidence: 99%
“…For transparent materials like glass, the birefringence method is customarily used for residual stresses measurement [13,14] . Strips were cut from the part with a low speed diamond saw (Isomet low-speed saw, Buechler).…”
A numerical simulation model for predicting residual stresses which arise during the solidification process of pressed glass bulb panel was developed. The solidification of a molten layer of glass between cooled parallel plates was used to model the mechanics of the buildup of residual stresses in the forming process. A thermorheologically simple thermoviscoelastic model was assumed for the material. The finite element method employed was based on the theory of shells as an assembly of flat elements. This approach calculates residual stresses layer by layer like a truly three-dimensional calculation, which is well suited for thin pressed products of complex shape. An experimental comparison was employed to verify the proposed models and methods.
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