Laminated Glass Windows Research Articles

A high explosive blast simulator

Window facades are heavily used in modern design. To ensure that the facade can withstand sufficiently large blast loads, experimental evaluation of the entire facade is crucial. In this study, we present the High Explosive Blast Simulator (HEBSim), an outdoors modular explosive-driven blast simulator with a large cross-section designed for real-size blast testing of glass facades. To evaluate the performance of HEBSim, we performed two test series, one with a rigid steel plate component and one with deformable laminated glass window components. Pressure sensors were used to measure the overpressure histories for both test series and deformation data was gathered using three-dimensional digital image correlation (3D-DIC) for the window component tests. The test series demonstrated that HEBSim generates planar and repeatable blast load profiles in line with explosive pressure resistance (EPR) classifications for various charge masses. In addition, the window component test series illustrated the stochastic fracture behavior of glass. Based on the presented data, HEBSim is found suitable for blast testing of large glass facades.

Experimental and numerical study on dynamic behavior of laminated glass window under combustible gas explosions

In this paper, full-scale field tests and numerical simulations are used to study the dynamic behaviour and destruction process of the laminated glass windows under combustible gas explosions. The blast overpressure caused by the explosions of combustible gas, the mid-span displacement and damage process of the windows were all documented during the field tests. The results are analyzed and presented in this paper. It is found that the laminated glass windows under blast loads of combustible gas explosions exhibit a characteristic bending failure, which differs from those under high explosives explosions. Numerical model of dynamic behaviour and destruction of laminated glass windows is developed in LS-DYNA and validated by the test results. The factors affecting the resistance of laminated glass windows to explosions of combustible gas are analyzed through numerical simulations. The results show that increasing the thickness of the glass panel and the interlayer, using soft supports and providing sufficient bite depth for the laminated glass window can significantly enhance its capacity to resist combustible gas explosions.

Influence of panels size on the static and dynamic performance of laminated glass panels

Laminated glass is made by joining two or more glass layers together using a polymeric interlayer which can significantly minimize the risk of flying shards and dissipate a great deal of energy after the glass cracking stage. In this paper, tensile tests are conducted on three different polymeric films i.e., PVB, EVA, and SentryGlas (SG) at two different strain rates to characterize the mechanical properties of the interlayer. In addition, a static full-scale water chamber was used to study the effect of panel size on the characteristic failure and deflection of the laminated glass windows experimentally. However, due to the high risk and cost of explosion experiments, dynamic modeling of laminated glass window systems is presented in this paper using ANSYS AUTODYN. The accuracy of the dynamic model is verified with previously published experimental data. Material characterization tests showed that SG film has the highest strength, which appeared significantly also in the static panel test and numerical. In addition, the maximum reduction in panel static strength due to size increase was observed in panels with SG and PVB interlayers with a maximum reduction of 58%. However, SG showed a lower dynamic response under blast loads.

Study on blast resistance for SiO2 nonmetallic material based on a multi-factor orthogonal experiment

To analyze the performance of SiO2 nonmetallic material, the (Ctitiacal Content, CC) of several types of laminated glass was calculated by FEM simulation. From the changes of measuring factors, the principal elements that influence the blast resistance of double laminated glass, from big to small, are the thickness of the glass, short-to-long side ratio of the glass panel and the thickness of the interlayer. The significant analysis results show that when the glass is 8 mm thick, the interlayer is 0.76 mm thick and the size of laminated glass is 900 × 900 mm, the laminated glass window was good at blast resistance.

Experiment and Simulation of Critical Parameters for Building Windows under Thermal Explosion

The personal awareness of explosion protection increases consequently with the terrorist threat throughout the world in recent years, so explosion protection becomes a worldwide problem. People pay more and more attentions to the explosion-proof of building. Glass window is the weakest component of a building. Therefore, it is very important to study the explosion-proof performance of glass windows for improving the building protection capability. The experiment is the most intuitive method to detect the explosion-proof performance of glass windows. The critical safety distance of the glass window under small explosion load was measured by experiment in this paper. However, due to the high risk and cost of explosion experiments, so the experiment data were rather rare. For comprehensive understanding the explosion-proof performance of laminated glass windows, the critical charge for double laminated toughened glass under explosion was simulated. According to the fitting curve of critical charge, the empirical formulas for calculating the critical charge for laminated glass windows with three panel sizes, three glass thicknesses and four interlayer thicknesses are obtained at different distances. The error analysis shows that the empirical formulas are accurate and available, which can provide some reference for the anti-explosion design of laminated tempered glass.

Numerical analysis of dynamic responses of laminated glass window subjected to gas explosions

Gas explosion is one of the main forms of accidental explosions that may cause significant loss of lives and economy. However, the researches on the dynamic responses of structures or structural members under gas explosion are still very limited. The current analysis and design approaches of structures against accidental gas explosions specified in design guides are mainly based on equivalent methods to predict loads from gas explosions, which may not necessarily give accurate explosion loads predictions and hence structural response estimations. Since the flying fragments from damaged architectural glass windows and façades induced by gas explosions are one of the main reasons to cause injuries in such an event, it is essential to accurately predict the damage and dynamic response of architectural glass structures subjected to gas explosion load for developing effective technology to mitigate the hazard from gas explosions. In this paper, the dynamic responses and failure modes of laminated glass window under TNT and gas explosions are firstly simulated with the validated numerical model, and the results are compared and analyzed. The results show that the laminated glass window under gas explosions experience typical bending failure, which is different from the case of laminated glass window under TNT explosions, implying the TNT equivalence method normally used to predict the blast loads for structural design against gas explosions may not lead to reliable predictions. To quantitatively demonstrate the differences, blast loads recorded in three gas explosion scenarios and the corresponding blast loads estimated by the TNT equivalence method are used to predict the dynamic response and damage of laminated glass windows. It is found that the TNT equivalence method for predicting gas explosion load in a vented room, in a partially confined chamber and in free field lead to over predictions of the responses of the laminated glass window. Parametric studies are also carried out to explore the influences of some key parameters, i.e., window size, glass panel thickness, interlayer thickness and boundary conditions on the response of laminated glass window subjected to gas explosion. The results indicate that increasing the glass and interlayer thickness, increasing the ratio of length to width of the laminated glass window, and adopting soft support constraints could greatly reduce dynamic responses and damage of the laminated glass window subjected to gas explosions.

Strengthening of Laminated Glass Windows against Windborne Debris Impact

This paper presents numerical modelling to study potential mitigation methods to improve the impact resistance performance of laminated glass windows against timber windborne debris impact. A detailed numerical model of laminated glass window is generated and validated with laboratory impact tests. The influence of supporting frames made of different stiffness materials is examined. Numerical simulation shows that boundary condition has limited influence to the penetration resistance of laminated glass windows. Then, the dynamic response of doubly laminated glass windows of the same total thickness as that of singly laminated glass windows is studied, which finds that optimization of glass and interlayer layout could effectively improve the penetration resistance of laminated glass windows.

Effect of the polymer interlayer on the high-velocity soft impact response of laminated glass plates

The choice of the polymer interlayer is a key consideration for laminated aircraft windshields. Such windshields often employ chemically strengthened glasses and are required to withstand impact by birds, hail-stones and other foreign bodies. In the present study, windshields employing three different polymer interlayer materials were investigated under high-velocity impact by a soft projectile: Thermoplastic Polyurethane (TPU), Polyvinyl Butyral (PVB) and Ionoplast interlayer-SentryGlas® Plus (SGP). Parameters such as the polymer interlayer type and thickness, multi-layering the interlayer and the sensitivity of the behaviour of the windshield to the environmental temperature were studied. The performance was assessed through a series of laboratory-scale impact experiments (using a bird-substitute material) and modelled via finite element simulations (using a smoothed particle hydrodynamics approach). The experimental and numerical results were found to be in good agreement for the three polymer interlayers investigated. The polymer interlayer type was found to have the most significant effect on both the deformation and the failure of the laminated glass windows at room temperature, i.e. 25 °C. However, the influence of the polymer interlayer type became less pronounced at lower temperatures. The novel modelling that has been developed assists in the choice of the best polymer interlayer, including the multi-layering of interlayers, for complex windshield designs.

Quasi-static bending and low velocity impact performance of monolithic and laminated glass windows employing chemically strengthened glass

In this paper, firstly the quasi-static bending performance of chemically strengthened alumina silicate glass plates is investigated for different glass thicknesses: 2.2, 4.0 and 6.0 mm. The flexural strength is measured using coaxial double ring experiments. The 3D Digital Image Correlation (DIC) technique is employed to measure the strain at failure. The failure probability is then assessed using the Weibull statistical distribution. Secondly, the performance of the laminated glass windows made of these chemically strengthened glass plates is evaluated quasi-statically under concentrated and distributed loadings. The effects of polymer interlayer thickness, glass and polymer type and multi-layering the polymer interlayer on the structural performance are investigated. The type and thickness of the polymer interlayer, as well as the type of loading are found to influence the fracture sequence in the glass plates and consequently the post fracture safety of the structure. The response of laminated glass specimens is then assessed under low velocity soft impacts, for velocities up to 3.3 m s−1, using a drop tower facility. Laminated glass with a polyvinyl butyral (PVB) interlayer shows the greatest improvement in terms of peak force and absorbed energy.

Deformation and damage mechanisms of laminated glass windows subjected to high velocity soft impact

Bird strike can cause serious risks to the safety of air travel. In this paper, the aim is to improve design by determining deformation and damage mechanisms of laminated glass windows when subjected to high velocity soft impacts. To achieve this, laboratory-scale impact experiments using bird substitute materials were performed in the velocity range of 100–180ms−1. An important step forward is that high-speed 3D Digital Image Correlation (DIC) has effectively been employed to extract the full-field deformation and strain on the back surface of the specimens during impact. The finite element simulations were performed in Abaqus/explicit using Eulerian approach and were able to represent successfully the experiments.For the laminated glass structures investigated, the damage inflicted is strongly sensitive to the nose shape of the projectile and most deleterious is a flat-fronted projectile. Two threshold velocities for impact damage have been identified associated with firstly the front-facing and secondly the rear-facing glass layer breaking. The order of the glass layers significantly influences the impact performance. The findings from this research study have led to a deeper and better-quantified understanding of soft impact damage on laminated glass windows and can lead to more effective design of aircraft windshields.

Delamination properties of laminated glass windows subject to blast loading

Delamination processes absorb significant amounts of energy in laminated glass windows when they are subjected to blast loads. Blast tests were performed previously and their results had been used to calculate the loads imposed on the support systems. In this research, the delamination process at realistic deformation rates was studied to understand the reaction force response obtained. Laboratory tensile tests were performed on pre-cracked laminated glass specimens to investigate their delamination behaviour. The experiments confirmed the presence of a plateau in the force-deflection graphs, suggesting that the delamination process absorbed significant energy. The experimental results were then employed to calibrate FEA models of the delamination process with the aim of estimating the delamination energy of the polyvinyl butyral (PVB) membrane and glass layers and its relationship with deformation speed. The delamination energies obtained through this research, if used with the appropriate PVB material model, are a valuable new tool new tool in the modelling and design of laminated glass façade structures.

The response of glass window systems to blast loadings: An overview

The failure of glass windows in terrorist bombing attacks and accidental explosion incidents has been cited as one of the major causes to the vast casualties. Many studies have been carried out to investigate the response and vulnerability of glass windows against blast loadings. These include laboratory and field tests that have been carried out to experimentally study glass window performance under explosion scenarios and development of analytical and numerical models to analyze and predict glass window responses. This article reviews literatures on the studies of the response of glass window systems to blast loadings. Over 100 papers and documents that are available in the open literature are reviewed. The background and history of the studies on the topic are also briefed. Understandings about the dynamic material properties of glass and available material models are summarized. Popularly used analysis methods and design standards for monolithic and laminated glass windows are outlined, and their accuracies are discussed. Recent studies including analytical solution, numerical simulation, and experimental investigations on glass window systems are summarized. Mitigation measures for blast-resistant windows are also briefly discussed.

Design of Blast-Loaded Glazing Windows and Facades: A Review of Essential Requirements towards Standardization

The determination of the blast protection level of laminated glass windows and facades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with respect to this kind of application. This paper attempts to give a first idea of a possible standardization concerning such numerical simulations. Attention is drawn to the representation of the blast loading and to the proper description of the behaviour of the material of the mentioned products, to the geometrical meshing, and to the modelling of the connections of the glass components to the main structure. The need to validate the numerical models against reliable experimental data, some of which are indicated, is underlined.

Reaction forces of laminated glass windows subject to blast loads

Several blast trials on laminated glass windows have been performed in the past, using both full field 3D Digital Image Correlation and strain gauges located on the supporting structure to collect information on the glass pane behaviour. The data obtained during three blast experiments were employed to calculate reaction forces throughout the perimeter supports both before and after the fracture of the glass layers. The pre-crack experimental data were combined with finite element modelling results to achieve this, whilst solely experimental results were employed for post-cracked reactions. The results for the three blast experiments were compared to identify similarities in their behaviour. It is intended that the results can be used to improve the existing spring–mass systems used for the design of blast resistant windows.

Experimental and theoretical study on the effect of window films on building energy consumption

Solar control films are designed to absorb or reflect the incident solar radiation, in order to reduce solar transmission through window glass. In the present study, the glass surface temperatures were measured for selected solar window films on various applications, and compared to the cases of the same window glass types without solar window films. Dynamic simulation models are also developed with the aid of the building energy simulation program EnergyPlus. After experimental validations, the computer models are used to evaluate the energy saving potentials of the subject samples of solar window films as applied onto glazing of three different function rooms in Hong Kong, namely office, shopping mall and hotel guest room. The results show that the thermal performance of the film applications on clear glass is better than on tinted or laminated glass windows. Solar films have very good energy saving potential when applied to all three functional areas in commercial buildings, and the best results are found in office applications.

Experimental and numerical study of boundary and anchorage effect on laminated glass windows under blast loading

Over the years extensive studies have been conducted to analyze the response of laminated glass panes under blast loading for personnel and property protection. The failure modes of glass windows in most of those studies are related to flexural bending of the glass panel. The problems of laminated glass failure at boundaries along window frames, as well as the influences of window frame constrain effect and the interlayer anchorage on the overall response of laminated glass panels are less examined. In this paper, experimental and numerical studies are carried out to examine the boundary conditions and interlayer anchorages of laminated glass windows on their responses under blast loadings. Blast tests were designed and conducted on window specimens with different frame bite depths, fixed or sliding boundaries and different interlayer anchorages. Numerical model of laminated glass windows is also developed. The accuracy of the numerical model in prediction of glass window responses is verified by field blast testing results. The validated numerical model is used to perform intensive simulations to study the window boundary conditions and interlayer anchorage measures on glass window responses to blast loadings. The results demonstrate that properly designed window frame and interlayer anchorage will increase the survivability of laminated glass windows under blast loadings.

Experimental study of laminated glass window responses under impulsive and blast loading

Laminated glass panes are widely adopted as blast-resistant glass windows to mitigate the hazard from ejecting fractured glass fragments. The response of laminated glass windows under blast loads is often predicted by equivalent static analysis or simplified equivalent single degree of freedom (SDOF) analysis. The equivalent SDOF and equivalent static analyses are also respectively adopted in UFC and ASTM design guide for glass window designs. Owing to the inherent problems, the SDOF analysis can only predict the global responses of glass windows and the predictions are not necessarily always satisfactory. Therefore the accuracy and applicability of the SDOF analysis is sometimes questioned. Often numerical simulations and/or experimental tests have to be carried out for reliable predictions of laminated glass window responses to blast loads. In this study, experimental tests on laminated glass windows subjected to impact and blast loads were carried out to evaluate the accuracy of available analyses and design methods. Pendulum impact tests were conducted first on laminated panes of various thicknesses. Full-scale field blast tests were performed on laminated glass windows of dimension 1.5 m × 1.2 m. Glass pane deflections were monitored by mechanical linear voltage displacement transducer (LVDT) and high-speed cameras. The responses of the tested windows are compared with the estimations of SDOF models and design standards in this paper. Available blast testing data by other researchers are also included together with the current testing data to evaluate the accuracy of the SDOF and equivalent static analyses defined in the design guides. The adequacy of these simplified approaches in predicting laminated glass window responses to blast loads is discussed.

Dynamic material model of annealed soda-lime glass

Glass is an omnipresent material which is widely used as façade in buildings. Damage of glass windows and the associated glass fragments induced by impact and blast loads impose great threats to people in the vicinity. Much effort has been directed towards understanding glass material properties, and modeling of glass window responses to impact and blast loads. For reliable predictions of glass structure performances under dynamic loadings, an accurate dynamic constitutive model of annealed float glass, which is commonly used for glass windows, is therefore needed. In current practice, the Johnson-Holmquist Ceramic (JH2) model is most commonly used in simulating glass plate responses to impact and blast loads. In this study, the accuracy of the JH2 model in modeling annealed float glass material, especially at high strain rate is examined in detail. Static compressive tests and dynamic compressive tests using Split Hopkinson Pressure Bar (SHPB) are carried out on soda-lime glass specimens sampled from commercially used annealed float glass panes. These testing results are used together with the authors' previous testing data and data reported by other researchers in the literature to determine the constitutive constants for the JH2 model, including Equation of State (EOS), strength criterion and strain-rate effect. The JH2 model with new material constants is then programmed in commercial code LS-DYNA. To verify the model, it is used to simulate a SHPB compressive test on a 15 mm by 15 mm (diameter by length) glass specimen, a field blasting test on a laminated glass window of 1.5 m by 1.2 m in dimension, and a full-scale laboratory windborne debris impact test on a laminated glass window. The simulation results demonstrate that the JH2 model with the new material constants for annealed glass gives good predictions of glass material and glass window responses to impact and blast loads.

Spectrally-selective all-inorganic scattering luminophores for solar energy-harvesting clear glass windows.

All-inorganic visibly-transparent energy-harvesting clear laminated glass windows are the most practical solution to boosting building-integrated photovoltaics (BIPV) energy outputs significantly while reducing cooling- and heating-related energy consumption in buildings. By incorporating luminophore materials into lamination interlayers and using spectrally-selective thin-film coatings in conjunction with CuInSe2 solar cells, most of the visible solar radiation can be transmitted through the glass window with minimum attenuation while ultraviolet (UV) radiation is down-converted and routed together with a significant part of infrared radiation to the edges for collection by solar cells. Experimental results demonstrate a 10 cm × 10 cm vertically-placed energy-harvesting clear glass panel of transparency exceeding 60%, invisible solar energy attenuation greater than 90% and electrical power output near 30 Wp/m2 mainly generated by infrared (IR) and UV radiations. These results open the way for the realization of large-area visibly-transparent energy-harvesting clear glass windows for BIPV systems.

The Development of Micro Ball Supersonic Impact Test System

A micro ball supersonic impact test system was developed for the study of dynamic fracture of ceramic materials. This system consists of (1) low pressure gas gun, (2) sabot assembly and stopper block for velocity multiplication system, (3) velocity measurement device for sabot and ball, and (4) enclosed target box for final impact test. The principle of velocity multiplication system is similar to two stage gun. The plastic sabot assembly houses steel plunger and the void filled with silicone rubber. The sabot is stopped by the stopper block then the steel plunger inside the sabot compress the silicon rubber to high pressure to rupture the plastic membrane. Then the compressive energy of the silicon rubber is transferred to the ball. More than ten times of initial speed was attained. Non-contact velocity measurement system uses two set of ribbon laser with optical array sensor to measure the supersonic speed of the micro ball. Maximum speed up to 1200m/s for plastic and 600m/s for steel ball was attained. Perforation test of plastic film laminated glass window was successfully done by the developed impact system.