Float Glass Plates Research Articles

Damage patterns in float glass plates: Experiments and peridynamics analysis

In this study ring bending tests on plates are performed to analyze the tensile strength of tin and air sides of float glass. Fracture stress values computed from experimental data applying the plate theory are analyzed by means of Weibull distribution. Probability of failure vs. fracture stress plots show much higher scatter for the air side than for the tin side. The linear peridynamic solid constitutive model coupled with damage is applied to simulate the ring bending, up to the critical state of crack initiation and early stage of crack propagation. A convergence study with respect to the number of nodes is performed. The simulated sequence of initial damage patterns, including the bond breakage inside the load ring and the formation of ring damage zone followed by initiation of radial cracks agrees with experimental observations for most specimens with tin side subjected to tensile deformation. A novel procedure to identify the critical bond stretch in the damage model based on experimental data for the critical ring force is proposed. The corresponding characteristic values are presented for both tin and air sides of the float glass.

Response of laminated float glass to 9 mm projectile impact

This paper presents an experimental study on the performance of laminated float glass plates against high-velocity projectile impact. Two configurations of the specimen’s layers were used, 5 layers (3 glass and 2 polymer interlayers) and 7 layers (4 glass and 3 polymer interlayers). The specimens were suspended on steel ropes for stress-free boundary conditions. The projectile was a standard in-service 9 mm Luger fired from a distance of 20 m. The results showed that both layer configurations are more than capable of stopping the projectile. However, only the higher layer count was able to stop the formation of significant damage to the backside of the specimen, from which a certain amount of harmful debris could have been released. The higher layer count also prevented the formation of radial cracks.

The effect of the loading system on the modulus of rupture of a rectangular glass plate

Strength determination of rectangular float glass plates is commonly carried out by standard tests. Different standards include different requirements of the specimen geometry, loading set up, sample size, etc. It is known that the modulus of rupture depends on the specimen’s area. This paper shows that it is also dependent on the loading system, and the dominating parameters affecting the experimental modulus of rupture are investigated. The loading system significantly affects the modulus of rupture and this finding raises a question with respect to the testing guidelines appearing in different standards and the experimental results thereby obtained.

Size effect of the modulus of rupture in float glass plates

This paper investigates the modulus of rupture of float glass plates of different sizes aiming at determining the effect of the plate area on its flexural tensile strength. Currently, the Weibull statistical distribution expression, which is calibrated with test data, is used for estimating the area dependent size effect. The present investigation is based on a theoretical stochastic model that is independent of test data. The numerical analysis simulates large size samples of plates and is based on the glass plate geometry, the boundary conditions, the specific loading data and implements the glass properties through a flaw distribution model characterizing the glass plate material. Very large size samples are required to obtain a converged solution. The model analysis yields higher strengths for smaller plates and the predicted tensile strength depends on the loading method. To eliminate the effect of the loading system on the size effect it was hypothesized that the fracture origin area, rather than the entire plate area, dominates the behavior. The fracture origin area for typical loading systems was determined from the model analyses. Implementation of this hypothesis shows that all tensile strength results for large samples of plates subjected to different loading systems follow a single common size-effect curve, which depends on the fracture origin area and is independent of the loading system. The calculated nonlinear stress ratio spans over almost five orders of magnitude of the plate area, considerably beyond the limited range of plate areas appearing in the literature. Comparison of the theoretically based size effect function with the empirical Weibull based data in the literature, shows similar results for relatively large area plates but an increasing difference for smaller areas, where the extrapolated empirical stress ratio law considerably underpredicts the theoretical results. Comparison of the calculated stress ratio results with test data shows very good agreement.

Three-dimensional (3D) dose distribution measurements of proton beam using a glass plate

The measurements of the three-dimensional (3D) dose distribution of proton beams in water are critical for proton therapy for quality assessment (QA). Although ionization chambers are commonly used for this purpose, such measurements take a long time to calculate precise 3D dose distribution. To solve this problem, we measured 3D dose distributions using a glass plate. We placed a 1-mm thick float glass plate on the upper inside of a black box with a water tank set above the float glass plate outside the black box and irradiated the proton beam to the water tank from the upper side. The attenuated proton beam by water in the tank was detected by the float glass plate and a scintillation image was formed in the plate. The image was reflected by a first-surface mirror set below the float glass plate and detected by a cooled charge-coupled device (CCD) camera from the side. We changed the water depths in the tank and measured the scintillation images at each depth. Then we calculated the 3D scintillation images from the measured images by stacking them in the depth direction. Measurements were made for 71.2- and 100-MeV proton pencil beams and a spread-out Bragg peak (SOBP) using the imaging system. From the images, we successfully formed 3D scintillation images without quenching. The depth profiles measured from the scintillation images showed almost identical distribution with those measured by the ionization chamber within a maximum difference less than 5%. The lateral profiles were also almost identical within width differences less than 2 mm. We conclude that our proposed method is promising for the 3D dose distribution measurements of proton beams.

Fracture and fragmentation of blast-loaded laminated glass: An experimental and numerical study

In this study, we use the explicit finite element method in combination with higher order elements and 3D node splitting to simulate fracture and fragmentation of blast-loaded laminated glass. Node splitting is a modelling technique where elements are separated instead of being eroded when a fracture criterion is reached. The resulting FE simulations are thus capable of describing behaviours such as fragmentation without loss of mass or momentum, fine cracking of the glass plates, and delamination and separation between the glass and the polymer interlayer. The simulations are compared to blast experiments conducted in a shock tube. In total, 15 laminated glass specimens (consisting of annealed float glass plates and PVB) were tested at five different pressure levels. The time and position of fracture initiation in the glass plates varied, which in turn resulted in varying post-fracture behaviour within the different pressure levels. The simulations were in good agreement with the blast tests, revealing the potential of the selected numerical method. Additional simulations of monolithic (i.e., non-laminated) glass plates were conducted and compared to experiments that were presented in an earlier study. Again, these simulations displayed a highly comparable response to the experiments, and were able to describe crack branching, formation of large glass splinters and free-flying fragments.

On the Dynamic Response of Laminated Glass Exposed to Impact Before Blast Loading

In this study, the effect of fragment or bullet impact before blast loading on laminated glass is studied experimentally. First, laminated windows consisting of two 3.8 mm thick annealed float glass plates and a 1.52 mm thick PVB interlayer were blast loaded in a shock tube with various pressures as a reference. In these tests, the blast loading was successively increased until fracture occurred not only in the glass plates but also in the PVB interlayer. Second, a diamond drill was used to make a 5 mm diameter centrally placed hole in some windows before they were blast loaded with the same pressures as those used for the undamaged windows. Third, windows were impacted by 7.62 mm AP bullets, both with and without the brass jacket, before they were blast loaded. Such bullets may have similar mass and velocity to typical primary fragments from an explosive detonation. The results are finally compared with each other and discussed with respect to the blast protection offered. It is found that the capacity is significantly reduced if the laminated glass is perforated by a fragment or a bullet before it is blast loaded and that such impacts should be considered in the design of blast-resistant windows.

Imaging of the scintillation light of float and silica glasses during irradiation of radiations

Although luminescence of water during radiation irradiations with energy lower than the Cerenkov-light threshold were found recently, it was not still obvious whether the luminescence or scintillation is produced or imaging is possible in commonly used float or silica glass. Thus we tried to image the produced light from plates and a block made of float or silica glasses during irradiations of radiations. We clearly detected the images of the produced light of glass plates by using an electron multiplied (EM) CCD camera during irradiation of alpha particles for silica glass and float glass. The silica and float glass plates produced 13 photons/MeV and 258 photons/MeV for alpha particles, respectively. The light spectrum showed high intensity for longer wavelength in silica glass plate and it was relatively broad for float glass plate. By combining the float glass plate with a photomultiplier tube (PMT), energy spectrum could be measured for 5.5 MeV alpha particles with the energy resolution of 65% FWHM. We also measured the scintillation image during irradiation of proton to a float glass block. The image in float glass block during irradiation of proton showed light distribution similar to the dose in the glass. These results suggest float or silica glass plates or blocks are promising materials for radiation detection and imaging.

Quasi Two-Dimensional Evaporation and Boiling Under Reduced Pressure

To study the washing mechanism of laminated plates with solvent vapor, we have experimentally investigated evaporation dynamics of liquid confined between solid plates under reduced pressure. As the test liquid, we use deionized water and several organic compounds. To visualize the fluid motion in the thin gaps, we adopt glass plates. When a test liquid is sandwiched between a normal (float) glass plate and a ground (sand-blasted) one, vertically incident light passes through the plates without much scattering; once the liquid starts to evaporate, dried rough surface of the ground glass scatters the light and we can monitor the flow pattern. Based on the transmitted light intensity, the whole plate area is categorized into three regions; completely wet, completely dry, and semi-dry one; the last one is supposed to be the state that thin liquid film spreads on the plate. In the case of water, many tiny spots of semi-dry region appear and expand at the initial stage, which is probably cavitation of dissolved gas. In organic liquid cases, evaporation seems to start from the edges of the plates. At a later stage, the semi-dry region expands with complicated branching patterns. In all cases, occasional rapid motions of liquid were observed, which correspond to two-dimensional flash boiling. We also investigated the influence of the control pressure, the surface roughness, and the plate deformation.

A thin float glass MRPC for the outer region of CBM-TOF wall

A Multi-gap Resistive Plate Chamber (MRPC) made out of thin float glass is proposed for the outer region of the time of flight (TOF) system for the Compressed Baryonic Matter experiment at FAIR. Usually MRPCs are assembled with ordinary glass plates of 0.5mm or more thickness, but their rate capability is less than the CBM requirement (1.5kHz/cm2). There are two ways to improve the rate capability. The first way is to reduce the bulk resistivity of the glass plates. The second is to reduce the thickness of the glass plates. Tsinghua University has made significant progress in the development of low resistive glass and high rate MRPCs. In this paper we report on three MRPCs produced with float glass plates of 0.7mm, 0.5mm and 0.35mm thickness. Tests with cosmic rays and X-rays were performed at Tsinghua University. The results show that thin float glass MRPCs work well and have the rate capability necessary to meet the demands of the CBM-TOF outer region. Further studies were performed using a continuous 1GeV deuterium beam at the Nuclotron accelerator at the Joint Institute for Nuclear Research (JINR). Time resolution of about 70ps and efficiency higher than 90% were obtained for flux densities up to 3kHz/cm2, exceeding the requirement for the CBM-TOF outer region.

Sphere-to-Plate Glass Welding using Picosecond-Laser Radiation

Welding of a spherical shaped glass beads with the diameter of 0.7 mm to a float glass plate by using picosecond laser irradiation was investigated. The glass bead itself acts as focusing lens and should be considered as a part of optical system. The different number of pulses, repetition rate and average laser power were applied to estimate the joint strength dependence on the laser process parameters. Modeling of transient thermal fields induced by laser irradiation was performed in order to evaluate a possible defect formation. Two types of crack-free welding regimes were found, namely, the point welding with a low number of laser pulses and a weak joint and the fusion welding when irradiation lasts up to one second. The joint area is significantly larger and the glass bead can withstand higher compression stress which is important for application in vacuum isolated glasses. The processes still need to be optimized in terms of productivity.

Picosecond Laser Welding of Spherical Glass Bead to Substrate

Welding of a spherical shaped glass beads with the diameter of 0.7 mm to a float glass plate by using picosecond laser irradiation was investigated. The glass bead itself acts as focusing lens and should be considered as a part of optical system. The different number of pulses, repetition rate and average laser power were applied to estimate the joint strength dependence on the laser process parameters. Two types of crack-free welding regimes were found, namely, the point welding with a low number of laser pulses and a weak joint and the fusion welding when irradiation lasts up to one second.

Effect of the tin- versus air-side plate-glass orientation on the impact response and penetration resistance of a laminated transparent armour structure

Our recently developed continuum-level, physically based, high strain-rate, large-strain, high-pressure mechanical material model for soda-lime glass has been enhanced to include differences in the flaw-size population between the so-called air-side and the so called tin-side of float-glass plates, and adapted for use in the case of borosilicate glass. The model was structured in such a way that it is suitable for direct incorporation, as a material user-subroutine, into standard commercial transient non-linear dynamics finite-element-based software packages. The model was parameterized using various open-literature sources. The experimental portion of the work, which consisted of 28 projectile impacts onto glass/polyurethane/polycarbonate-based test laminates, was intended to allow for quantification of the effect of air- versus tin-side borofloat strike surface when incorporated into a multi-layer, multi-functional test laminate. Experimental findings indicated the lack of a significant difference in the impact resistance of air- versus tin-side test laminate strike surfaces. Subsequent to these findings, computational simulations were carried out in order to establish if the proposed borofloat material model could capture the prominent experimentally observed damage modes and the measured V50, reconfirming the experimental findings. In general, a good agreement was found between the computational and the experimental results.

Investigation of rain erosion on a brittle material by means of numerical simulation

In this work, the resistance and deformation characteristics of a brittle material against rain erosion are examined by using the non-linear, explicit software LS-DYNA. The water jet with varying speeds impinges at 90° on silica float glass plates with different thicknesses. In the simulations, the Arbitrary Lagrangian Eulerian method is used for modelling of the water. In order to analyse the deformations on the brittle material Johnson–Holmquist–Ceramics (JH-2) is used as the material model. Minimum plate thickness (for constant water jet speed) and maximum water speed (for constant plate thickness), which do not cause any damage to the target, are determined depending on the geometry, boundary conditions and assumed failure strain value for erosion. The results are compared with the water-hammer pressure.

Development of MMRPC prototype for the NeuLAND detector of the R3B collaboration

Abstract A prototype of Multi-strip Multi-gap Resistive Plate chamber (MMRPC) with active area 40 cm × 20 cm has been developed at SINP, Kolkata as a new Time-Of-Flight (TOF) system with timing resolution σ t 120 ps and position resolution σ x ∼ 0.58 cm . The intention is to use multilayers of this type together with converter materials as a high energy neutron ( 1 GeV > E n > 200 MeV ) TOF system for the R3B collaboration at the FAIR facility. The design of the detector elements is as follows: a double stack MMRPC with float glass plates and two gas gaps of 0.3 mm per stack. The response of this MMRPC has been studied with cosmic muons and γ -rays from a standard radioactive source (60Co) in coincidence with fast inorganic scintillators at SINP laboratory. Recently, response of developed MMRPC has been studied using pulsed electron beam at ELBE, FZD. The details of the MMRPC construction , experimental set-up for investigation of its response and first results are presented.

A New Technique for Testing Abrasion Resistance of Refractories at Elevated Temperatures

Based on an extensive comparison of test methods for abrasion resistance from home and abroad, a new technique for abrasion resistance at elevated temperature has been developed with some improvements. Two connected airtight chambers are designed to prevent compressed air from entering the sample chamber, so that heat loss of the sample chamber can be reduced and the chamber temperature is less disturbed. The sample surface temperature can reach stable within 5 min and the temperature fluctuation on sample surface can be less than 20°C in the course of inleting the compressed air at working temperatures up to1400°C. The repeatability was tested using float-glass plate as reference sample at ambient temperature and using high alumina bricks for elevated temperature. A variation coefficient under 7% at ambient temperature has been achieved. Comparison of abrasion resistance at elevated temperature was tested respectively on a high alumina brick and on a silicon nitride bonded silicon carbide brick and the results could be significantly distinguished. Nitrogen can be blown into sample chamber during heating the furnace to prevent nonoxide bearing samples from being oxidized.

Stress Generation in Float Glass Plates Loaded with Blast Wave in a Vertical Square Shock Tube

In order to study a glass plate strength against loading by explosion, stress generation of 300 mm×300 mm×19 mm float glass by blast wave loading was investigated by using a vertical square shock tube. Blast wave was produced by a vertical shock tube with an improved high-pressure chamber by inserting a cone-shaped material. Stress generation after maximum value upon blast wave was dependent on the decay pattern of blast wave loading. Stress generation σ(t, d*) at time t and normalized non-dimensional thickness d* by blast wave loading can be shown as using as a function of time t, various parameters: dynamic coefficient, Cd, static coefficient, Cb, two factors ω and λ dependent on glass thickness, decay constant A and positive time of blast wave tp: σ(t, d*)=Cd sin ωt•exp{−λ(t-π/2ω)}+Cb{1−(t-π/2ω)/tp}•exp{−A(t−π/2ω)/tp}with an additional decay term to blast wave equation due to shock tube loading. Further, it is suggested that shock wave loading and blast wave loading have almost similar influence on failure of glass.

Experimental Study of Glass Strength against Shock Wave Loading-Stress Generation of Float Glass Plates-

Stress generation by shock wave on a 300mm×300mm float glass specimen was investigated. Stresses in float glass plate increased to a maximum value impulsively, and decayed accompanied by a periodical oscillatory pattern. The stress values σ so far generated can be written in the following form of time t and thickness d using 4 parameters, σ(t, d*)=Cdsinωt·exp{-λ(t-π/2ω)}+Cs. In these 4 parameters, Cd and Cs are shown as a factor of Mach number by normalizing with glass thickness, and λ and ω are dependent on glass thickness.

A study on penetration fracture characteristics of glass plates subjected to impact loadings

In this study, a comparison between theoretical solutions and experimental results are examined for fracture conditions in the case of float glass plates subject to static loadings. The ranges from fracture-generated initiations to critical penetration energies are confirmed according to the impactor mass under high velocity, and an analytical method is presented to determine the fracture strength and penetration strength. Also, fracture patterns are investigated according to impact velocities.

Crack branching in float glass subjected to biaxial loading

Failure of float glass plates in biaxial loading, occurs by well defined crack branching. As part of a study of the effect of handling damage on the strength of annealed glass, extensive observations have been made of crack branching in 4 mm thickness plates with strengths between 40 and 270 MPa, and more limited observations in plates of other thicknesses. Testing was carried out on discs loaded by hydraulic pressure against a circular anvil. For the 4 mm thick 280 mm diameter glass samples a 254 mm diameter anvil was used. Crack length at branching 2c b is related to the applied fracture stress σ b: σ b − σ 0 = A b/✓c b, where the branching constant, A b, is close to published mirror constants for uniaxial loading. The intercept σ 0 is larger than the residual surface stress in the sample, of which it is often considered to be a measure. The results have been analysed using the stress intensity factors for circular and elliptical cracks in a finite thickness plate and found to give good agreement with experiment for the variation of branch length with failure stress.