Strength Of Glass Research Articles

Determination of the bending strength of glass via four point bending: correction of factor ke in EN1288-3

AbstractEN1288-3 (Glass in building—Determination of the bending strength of glass—Part 3: test with specimen supported at two points (four point bending), 2000) describes the four point bending test for the determination of glass strength. The failure stress is calculated from the vertical force of the testing machine. To determine the difference between the stress calculated from linear 1st order theory and actual glass stress, a factor ke is given. This factor is derived from a 1994 publication (Blank in Glass Sci Technol 67:9–15, 1994) that uses a very simplified finite element model. The present paper will show that for tests with high deformation, which becomes more relevant for smaller glass thickness and chemically strengthened glass, these results differ vastly from the actual behaviour of the glass in the four point bending test as it is performed in most industry and lab settings. With the corrected curves for ke, increases in the characteristic edge strength of more than 50% compared to the current version of EN1288-3 can be derived from the four point bending test in some cases.

Strengthening mechanism and plasticity deformation of crystalline/amorphous Cu3Fe/Fe3Cu nanolayered composite

Metallic glasses possess high strength and excellent elastic properties due to their amorphous atomic structure. However, they often display brittleness and suffer catastrophic failure because of shear localization, without exhibiting significant macroscopic plastic deformation under tension. In this paper, an effective method to enhance the strength and ductility of metallic glasses is presented by molecular dynamics simulation. The approach involves controlling the thickness of the crystalline Cu3Fe and amorphous Fe3Cu layers. The results indicate that increasing the thickness of the crystal layer improves the strength of the nanolayered composite. The crystalline/amorphous interface impedes stress propagation in the shear transformation zone, thereby enhancing the yield stress of the composite. Additionally, the presence of Hirth dislocations in the crystal layer strengthens the composite. The generation and annihilation of fixed dislocations in the crystal layer cause stress fluctuations in the composite, which further enhances its ductility. However, a small content of crystalline layer can cause stress concentration towards the shear band, leading to rapid fracture failure and reduced ductility. These findings shed light on the plastic deformation behavior of crystalline/amorphous composites at the nanoscale, providing valuable theoretical guidance for designing high-strength and ductile metallic materials.

Tensile strength and crack tip stress distribution of modified glass in the composite laser beam separation

The tensile strength of the modified cross-section (MCS) determines to a certain extent whether the composite laser can complete the separation of glass, and the quality and efficiency of the separation. In this work, the effect of the picosecond Bessel laser on the tensile strength of soda-lime glass was systematically investigated for the first time. The relationship between the tensile strength and residual stress was not negatively correlated absolutely. The tensile strength was also related to the homogeneity and micro-structure of MCS, including micro cavities, cracks, and voids. Meanwhile, it was pointed out that by selecting appropriate modified parameters, the plasma shielding effect can be suppressed and the micro-morphology of MCS can be controlled to obtain smaller tensile strength and better cutting quality. Secondly, the stress field distribution at the crack tip was simulated to analyze the mechanism when the continuous wave (CW) laser interacted with the modified glass. The simulation results showed that only the stress perpendicular to the laser incidence direction and the scanning direction exceeded the tensile strength of glass material, ensuring that the cracks propagated only along the MCS. Finally, one-time separation of glass was achieved by using a composite laser beam separation (CLBS) technology with a speed of 50 mm/s, which was comparable to the industrial level, and the roughness of separated sidewall was less than 0.5 μm.

Methodology of residual strength prediction of composite structures with low-velocity impact damage based on NDT inspections and numerical-experimental CAI testing

One of the most challenging tasks is to evaluate a structural condition and predict a residual strength when damage is present in a composite structure. Such a prediction is usually performed based on experimental destructive testing on specimens, which often does not reflect the geometrical complexity of a component with damage, or based on numerical simulations, which are difficult to parametrize due to the complexity of fracture mechanisms of composite materials. In this paper, we proposed a hybrid methodology based on evaluation of results of the ultrasonic non-destructive testing technique supported with numerical modeling and compression after impact (CAI) tests to evaluate residual strength of glass- and carbon-reinforced polymer composite structures. Based on ultrasonic C-scans processing and incorporation of impact damage shapes in numerical models and further evaluation of the obtained results in the light of CAI tests, the model for the prediction of residual strength in composites was developed.

Quantitative fractography for brittle fracture via multilayer perceptron neural network

Quantitative fractography is instrumental in the failure analysis of brittle materials, yet the methodology is currently only applied to a handful of materials and loading scenarios as the generalization of the methodology is severely hampered by the unknown roles of many physical factors. With the development of computational tools, artificial neural networks (ANNs) are widely used in engineering and could provide a reliable connection between inputs and outputs. In this work, ANN models were used to analyze the fracture strength of various glasses and ceramics fractured in both flexure and tension. A large set of data consisting of over 4,500 experimental fracture surfaces obtained from 41 types of glasses and ceramics were collected from 82 references for training the models, and the best ANN models for analyzing each scenario were selected. The trained models were further validated by experimental fracture tests conducted in this study. This study showed that the developed ANN could often outperform accepted empirical relations in the literature when predicting the fracture strength and suggested that the developed ANN could be reliably extended to estimate the fracture strength of a broader set of brittle materials. However, it was concluded that for more accurate predictions in the case of ‘non-glass’ ceramics, additional relevant physical factors should be considered in the analysis.

Prediction model of long-term tensile strength of glass fiber reinforced polymer bars exposed to alkaline solution based on Bayesian optimized artificial neural network

The present study presents a model for predicting the long-term tensile strength of glass reinforced thermoset polymer (GFRP) bars based on the artificial neural network (ANN) algorithm, for bars which were exposed to alkaline solutions with different temperatures, different chloride ions concentration, and different applied stress levels. 272 groups of durability data of GFRP bars were collected from the literature. The correlation coefficients between each input feature and the target variable were calculated to analyze their relationships. The principal component analysis (PCA) method was performed to identify possible opportunities to reduce the input dimensions. Bayesian optimized search and randomized search were used and compared to tune and optimize the hyperparameters of the ANN model. Once the optimal ANN model was built, permutation feature importance, partial dependence plot (PDP), and SHapley Additive exPlanations (SHAP) value methods were used to interpret the optimal model. Results indicate that only the ultimate tensile strength has a high potential of being linearly changing with the long-term tensile strength of GFRP bars. PCA results show that the input dimensions cannot be reduced if 99% explained variance needs to be retained. The optimal ANN model trained through the Bayesian optimized search method can achieve a determination coefficient R2 and a mean absolute percentage error of 0.941 and 7.11%. Permutation feature importance and SHAP importance both ranked the initial ultimate tensile strength of GFRP bars as the most important input feature, followed by temperature, ageing time, diameter, applied stress level, pH value, and chloride ions concentration based on their SHAP values. On average, the PDP result of the ageing time tended to show that there will be a certain residual tensile strength of GFRP bars after ageing for a long period.

Improving the bond strength of bioactive glass coatings obtained by atmospheric plasma spraying

Bioactive glasses are inorganic biomaterials that can provide a bioactive response and thus favor the successful bonding of orthopedic implants. Some strategies were studied to improve the bond strength of bioactive glasses, such as producing agglomerated bioactive glass powders or designing different coatings combining hydroxyapatite (HA) with bioactive glass. The bioactive coatings were produced by atmospheric plasma spray (APS) onto titanium alloy substrates, and the microstructure and adhesion strength of the developed coatings were evaluated. It was found that a significant improvement in adhesion strength was obtained for the developed coatings, in particular when thermal treatment was applied to pure glass coatings and when HA was part of the coating. The coatings reactivity in simulated body fluid and Tris-HCl solutions was studied. All coatings showed bioactive behavior, but the ones with only an amorphous phase in the upper part of the coating dissolved faster, releasing a larger proportion of Ca ions, which caused faster nucleation and growth of apatite deposits.

Relationship of Temperature Dependences of Microhardness and Enthalpy of Glass on the Example of Selenium

A model is proposed that makes it possible to calculate the temperature dependence of the microhardness of glass over the entire temperature range from the softening temperature to absolute zero. The calculation uses the temperature dependence of the glass enthalpy and the value of its microhardness at the glass transition temperature. The proposed model is tested on the example of glassy selenium. For this, the temperature dependence of the microhardness of selenium on the softening temperature up to 100 K, which is 50 K below its Debye temperature, is measured. Thus, a relationship is established between the strength and thermodynamic properties of glass.

Effect of Process Parameters on Thermal and Mechanical Properties of Filament Wound Polymer-Based Composite Pipes.

The aim of this study was to investigate the mechanical and thermal properties of composite pipes based on epoxy resin and glass fibers produced by filament winding (FW) technology. Epoxy resins are widely used polymers in FW composite structures. The thermal characterization of the neat epoxy resin, curing, and post-curing characteristics for the determination of polymerization and glass transition temperature was performed, which is important for the mechanical properties of polymer composite pipes. In the present work, the applicability of the full factorial experimental design in predicting the hoop tensile and compressive strengths of glass fiber/epoxy resin composite pipes was investigated. The composite pipes in accordance with the 23 full factorial experimental design by using of three parameters and two levels of variation were prepared. The winding speed of the composites was taken to be the first factor, the second was the fiber tension, and the third was winding angle. To approximate the response, i.e., the mechanical properties of the composite pipes within the study domain, the first-order linear model with the interaction was used. The influence of each individual factor to the response function was established, as well as the influence of the interaction of the two and three factors. Additionally, those results were completed with the thermal characterization of the polymer composite pipes. From received results from mechanical and thermal characterization, it was concluded that the properties of composite specimens were highly affected by the analyzed parameters in filament winding technology. It was found that the estimated first-degree regression equation with the interaction gave a very good approximation of the experimental results of the hoop tensile and the compressive strengths of composite pipes within the study domain.

Study on dynamic response of high speed train window glass under tunnel aerodynamic effects

PurposeThis paper aims to analyze the bearing characteristics of the high speed train window glass under aerodynamic load effects.Design/methodology/approachIn order to obtain the dynamic strain response of passenger compartment window glass during high-speed train crossing the tunnel, taking the passenger compartment window glass of the CRH3 high speed train on Wuhan–Guangzhou High Speed Railway as the research object, this study tests the strain dynamic response and maximum principal stress of the high speed train passing through the tunnel entrance and exit, the tunnel and tunnel groups as well as trains meeting in the tunnel at an average speed of 300 km·h-1.FindingsThe results show that while crossing the tunnel, the passenger compartment window glass of high speed train is subjected to the alternating action of positive and negative air pressures, which shows the typical mechanic characteristics of the alternating fatigue stress of positive-negative transient strain. The maximum principal stress of passenger compartment window glass for high speed train caused by tunnel aerodynamic effects does not exceed 5 MPa, and the maximum value occurs at the corresponding time of crossing the tunnel groups. The high speed train window glass bears medium and low strain rates under the action of tunnel aerodynamic effects, while the maximum strain rate occurs at the meeting moment when the window glass meets the train head approaching from the opposite side in the tunnel. The shear modulus of laminated glass PVB film that makes up high speed train window glass is sensitive to the temperature and action time. The dynamically equivalent thickness and stiffness of the laminated glass and the dynamic bearing capacity of the window glass decrease with the increase of the action time under tunnel aerodynamic pressure. Thus, the influence of the loading action time and fatigue under tunnel aerodynamic effects on the glass strength should be considered in the design for the bearing performance of high speed train window glass.Originality/valueThe research results provide data support for the analysis of mechanical characteristics, damage mechanism, strength design and structural optimization of high speed train glass.

75‐3: Investigation of Influence and Improvement of Dry Etch on Glass Strength

None film surface of TFT glass will be damaged varying degrees due to physical contact with array equipment, which will seriously reduce the strength of none film surface. In this paper, we clarified the physical damage caused by the dry etch equipment on none film surface of TFT and its impact on the strength reduction through multiple verifications in array process. It is proved that strength reduction is mainly related to the back electrode material of dry etch. By changing the back electrode material from M to N(code name), the strength of the acrylic ball drop increased by more than 500%, and the strength of the cell ROR increased by 57%. This research has greatly improved the strength of none film surface of LCD, which is great significant to product performance improvement and new product certification.

Brilliability and fracture strength of float glass under static and dynamic loads due to radiation heat

In this research, steady state and thermal crack analysis was carried out on clear glass exposed to heat radiation with different thicknesses. The analysis process is carried out from the thickness of the glass and testing the temperature variation of the glass testing process to find out the maximum temperature limit of radiation exposure until the glass multiplies thermal crack with steady state analysis of the predetermined ideal heat time. The data collection method used in this study was through testing in an oven where data collection was based on the results of a thermal steady state analysis. The increase in temperature per minute from the first minute was 138.4 ⁰C to the 7th minute or the end was 179.3 °C, from the results research states that in the 7th minute the glass has experienced a crack or crack where the crack starts from the side of the glass which is insulated from radiant heat.

14‐3: Drop Resistance Optimization Through Post‐Hoc Analysis of Chemically Strengthened Glass

In the market of the mobile cover glass, the development of chemically strengthened glass is focused on the drop resistance improvement. The cover glass which protects the display panel is a typical brittle material that the micro cracks tends to be occurred underneath a glass surface by physical impacts. The micro cracks tends to be propagated by tensile stress and it is known as a general procedures on glass breakage. In purpose of the cover glass strength improvement, compressive stress is applied to the glass surface using chemical strengthening method by ion exchange. However, since the central area of the glass is relatively subjected to tensile stress, the glass is instantly broken when the propagated cracks are reached on the tensile stress exerted area. The glass specifications have been managed for maintaining the strength using parameters of compressive stress (CS), depth of compression (DOC), and central tension (CT). However, there was no method to judge the most effective factor for impact drop resistance. In order to solve this problem, we developed a machine learning program for cover glass that can predict the breakage height based on stress and mapped evaluation data based on the measured stress profile data and the actual drop breakage simulated evaluation. Especially, eXplainable AI (XAI) method is used to identify the effective factors on drop breakage height. And the test and measurement data were applied to various chemically strengthened glass for analysis.In this study, it was possible to predict the drop breakage height only by measuring the stress profile of chemically strengthened glass. The feature value of chemically strengthened that has the most effect on the drop breakage resistance on rough surfaces was identified to be stress value at 30um in the case of alkali aluminosilicate glass. And it was proved that the drop breakage height was improved by 25% only by increasing the compressive stress at 30um depth.

Non-destructive strength testing of microindented float glass by a nonlinear acoustic method

The present paper describes a method for non-destructive testing of the glass strength. Square 10 × 10 cm2 samples of annealed float glass was inflicted with a controlled defect in the centre of the atmospheric side using Vickers microindentation-induced cracking with a force of 2 N, 5 N and 10 N and compared to an un-indented reference. The samples were non-destructively tested using a nonlinear acoustic wave method resulting in defect values. The average of the defect values was found to linearly correlate to the indentation force in a log–log relationship. The samples were subsequently tested in a ring-on-ring setup that allows for an equibiaxial stress state. The indentation-induced cracking gave practically realistic strength values in the range of 45 to 110 MPa. The individual sample values for failure stress as a function of normalized defect value show linear trends with approximately half of the data within 95% confidence limit. In summary, this study provides an initial proof-of-concept for a non-destructive testing of the strength of glass.

Development and Performance Characterization of Lightweight Foam Glass Mixed with Coal Waste

Waste glass and fly ash are used as main raw materials, borax is used as fluxing agent, and calcium carbonate is used as foaming agent to prepare foam glass. The main factors affecting the performance of foam glass and the appropriate ratio and process were obtained by single factor test and orthogonal test. The macroscopic physical properties such as thermal conductivity and porosity of the product and XRD, DSC-TG and SEM microscopic performance tests were carried out. The results show that the CaCO3 content is 2%, the fly ash content is 10%, the foaming temperature is 875 °C, and the foaming time is 30 min. The thermal conductivity of the obtained foam glass can reach 0.050 W/(m•k). When the fly ash content is 20%, the compressive strength of the foam glass can reach 6.5 MPa.

Study to analyze the mechanical strength of composite glass fiber laminated with resin epoxy, resin polyester, and PVC foam under tensile loading conditions by numerically using finite element analysis via Ansys

With the development of material sciences, different kinds of materials are being developed and studied continuously. In order to significantly reduce weight and reduce emissions, composite materials are employed in aerospace, automobile, mechanical, and wind industries all over the world. Advanced polymer composites, which generally consist of continuous fibers inside a polymer matrix, give greater material qualities than metals and provide for the achievement of lightweight structural designs. Additionally, it is expensive and time-consuming to prepare samples and carry out studies with these materials. Therefore, finite element analysis and simulation have been chosen as the method for failure analysis in order to understand the complicated failure behavior of polymer matrix composite material. The primary goal of this study is to investigate the mechanical strength of glass fiber/resin epoxy, glass fiber/resin polyester, and glass fiber/PVC foam at the laminate level and lamina level under tensile loading conditions in Ansys and Ansys ACP. After analysis, this study has revealed that glass fiber laminated with resin epoxy composite has a higher life cycle and high stress-bearing capacity compared to glass fiber/resin polyester, and glass fiber/PVC foam.

Effect of boundary conditions on tensile bending strength of glass under four-point bending

Tensile bending strength is the most crucial property of structural glass. An evaluation procedure of tensile bending strength is specified in EN 1288-3 using the four-point bending (4PB) tests. However, the effects of boundary conditions of the supporting and bending rollers on tensile bending strength have not been well documented. The purpose of this paper is to provide a modified procedure for evaluating tensile bending strength considering the combined effects of boundary conditions and friction. The 4PB test method was re-evaluated by performing a comprehensive experimental, analytical and numerical study on ultra-white annealed glass (ANG) and fully tempered glass (FTG) subjected to large deflection. The results demonstrate that different boundary conditions can lead to a deviation between the EN 1288-3 standard method and the newly proposed evaluation procedure, which is strongly dependent on boundary conditions and friction effects. If laboratory conditions permit, it is highly recommended to ensure that the supporting and bending rollers can rotate freely during the 4PB test to avoid overestimating the tensile bending strength of structural flat glass. Otherwise, it is necessary to employ the newly proposed evaluation procedure to obtain the tensile bending strength accurately.

Effect of shatterproof polymer film application on the fracture types and strength of glass subject to bending load

Shatterproof polymer films are widely for windows used because they can be easily installed on existing glass windows to improve safety. Applying them to glass plates has been reported to not only prevent fragments from scattering but also increase load-bearing capacity and penetration resistance. However, the clarification of their mechanism and quantitative evaluation are still insufficient because the effect of film application on the strength and failure mode of glass under quasi-static loading has not been investigated. In this study, three-point bending tests and fracture surface observations were conducted on a float glass with a shatterproof polymer film. The stress field formed inside the glass was visualised during the tests using the photoelastic method. By varying the support span of the specimen, the deformation mode was varied to generate three types of failures: bending, shear caused by Hertzian contact stress, and mixed-mode failures. Under the conditions in the present study, the breaking loads of the specimens with and without film were almost the same; however, the fracture surface observation indicated that the area subjected to shear failure caused by Hertzian contact stress was larger with film application. Finally, the effect of the film thickness on the breaking load due to bending deformation was theoretically predicted.

Strength and Durability Properties of Waste Glass Based Self Compacting Concrete: A Review

Strength and Durability Properties of Waste Glass Based Self Compacting Concrete: A Review

Extra-High Pressure in the Core of Silica-Based Optical Fiber Preforms during the Manufacturing Process

The core refractive index n2 of silica-based optical fiber preform heated to 2000 °C was determined experimentally for the first time. The measurements were carried out in the process of preform temperature reduction. It was shown that n2 could increase up to ~1.75 in the visible spectral range at temperatures of ~2000 °C (n2 ≈ 1.46 at room temperature). This fact suggests that pressures close to or exceeding the ultimate strength of silica glass (~20 GPa) occur in the preform core region. The local extra pressure is argued to be a possible cause of the well-known “starburst” phenomenon at the core–cladding interface of preforms with certain core compositions. The observed effect of radial cracks can be interpreted as the result of silica cladding destruction under the action of extra-high pressure in the core.