Glass Laminates Research Articles

Sound Transmission Loss Analysis for Laminated Glass and Perspex

The aim of this study is to analysis the sound transmission loss (STL) for the laminated glass and Perspex. In this study, the STL of laminated glass and Perspex are determined using the two-load transfer function method (TFM) impedance tube measurement setup. There are 5 mm and 8 mm thickness of glass and Perspex were used. Glass and Perspex will be laminated into double and triple layer in order to investigate its STL due to interlayer effect. All the specimens are prepared into round shape with the diameter of 33 mm that fit with the inner diameter of impedance tube. From the measurement, it is concluded that the STL almost similar for the Perspex and glass without the layer lamination at the frequency range below 3500Hz. Number of interlayer for the glass or Perspex lamination plays the major role as main parameters that affect the overall STL.

Metallic glass nanolaminates with shape memory alloys

We model the deformation behavior of metallic amorphous Cu64Zr36/crystalline B2 CuZr nanolaminate systems using molecular-dynamics computer simulations. Amorphous-crystalline nanolaminates with shape memory alloys may be a material class which is combining the advantageous properties of metallic glasses with large-strain homogeneous flow at low temperatures and high stresses. We find that the deformation of the glassy and crystalline phases is a coupled process: martensitic transformation leads to shear band formation while the stress at the shear band tip induces martensitic transformation in the shape memory crystal. Moreover, the martensitic transformation changes the shear band morphology, stabilizes the shear flow and avoids a runaway instability. Finally, the critical volume fraction of the B2 layer for which the composite laminate shows a brittle-to-ductile transition is identified. The value of the critical volume fraction can be further decreased when the structure of the metallic glass is rejuvenated. Therefore, tailoring the architecture of metallic glass laminates with shape memory phases may allow the development of materials that exhibit large tensile ductility.

Numerical Analysis and 1D/2D Sensitivity Study for Monolithic and Laminated Structural Glass Elements under Thermal Exposure.

Glass is largely used in architectural and engineering applications (i.e., buildings and vehicles) as a structural material, especially in the form of laminated glass (LG) sections. To achieve adequate and controlled safety levels in these applications, the well-known temperature-dependent behavior of viscoelastic interlayers for LG sections should be properly accounted for during the design process. Furthermore, the materials’ thermomechanical degradation with increases of temperature could severely affect the load-bearing performance of glass assemblies. In this context, uncoupled thermomechanical finite element (FE) numerical models could represent a robust tool and support for design engineers. Key input parameters and possible limits of the FE method, however, should be properly calibrated and assessed, so as to enable reliable estimations for the real behavior of glazing systems. In this paper, FE simulations are proposed for monolithic (MG) and LG specimens under radiant heating, based on one-dimensional (1D) and two-dimensional (2D) models. A special attention is focused on thermal effects, being representative of the first step for conventional uncoupled, thermomechanical analyses. Based on experimental results available in the literature, FE parametric studies are discussed, giving evidence of limits and issues due to several modeling assumptions. In particular, careful consideration is paid for various thermal material properties (conductivity, specific heat) and thermal boundaries (conductivity, emissivity), but also for other influencing parameters like the geometrical features of samples (thickness tolerances, cross-sectional properties, etc.), the composition of LG sections (interlayer type, thickness), the loading pattern (heat transfer distribution) and the presence of additional mechanical restraints (i.e., supports of different materials). Comparative FE results are hence critically discussed, highlighting the major effects of such influencing parameters.

Experimental investigations into SGP laminated glass under low velocity impact

The structural use of laminated glass (LG) is growing rapidly. To meet safety and post-breakage strength requirements, a SentryGlas®Plus (SGP) interlayer has been widely used in LG. Limited data has been available to date concerning the impact resistance of SGP LG. This paper describes an experimental investigation into the damage behaviour of SGP LG panels under hard-body impact. A mean minimum breakage velocity (MMBV) test approach has been employed to determine the breakage energy. By tracing the crack initiation through the use of high speed filming, six categories of breakage sequence have been classified. The characteristics of crack propagation, including the lagging time between the initiation of different cracks and the typical crack propagation speed, were also obtained. This is followed by the identification of the representative cracking morphology and the motion behaviour of the impactor. The impact resistance of SGP LG has been calculated by examining the effects of the design variables such as the LG panel size, interlayer thickness, the support conditions and the glass make-up. It was found that the influence of LG panel size on the MMBV and both pre- and post-breakage stiffness is limited, and increasing the interlayer thickness cannot improve the resistance to glass breakage under impact. The LG panel with clamped edges requires more MMBV to trigger glass breakage and has an increase of 44% in pre-breakage stiffness compared to the panel with bolted connections at four corners. The evident improvement in post-breakage stiffness due to the beneficial fragmentation pattern of heat strengthened (HS) glass, compared to its counterpart of fully tempered (FT) glass, has also been revealed. However, the differences in MMBV between them are modest. Results also indicate that a significant degradation of dynamic stiffness in the post-breakage stage can be found in both the double layered LG with thicker interlayer, and in the triple layered LG. The energy dissipation behaviours were also examined, and results suggest that the energy dissipation ratio can be greater than 40% in most instances, and the thicker interlayer will produce negative effects on dissipating impact energy. Two types of delamination are identified, and the dependency of their delamination growth on the impact velocity is analysed.

Laser forming of glass laminate aluminium reinforced epoxy (GLARE): On the role of mechanical, physical and chemical interactions in the multi-layers material

The present work concerns the laser forming of Fiber-Metal Laminates (FMLs) by a high power diode laser source. FMLs are made of different layers of metal and composite material. The wide difference in the thermo-mechanical and physical properties of the different layers within FMLs makes them extremely problematic to be reprocessed. In particular, the economic shaping of FMLs in complex shapes is practically impossible, limiting greatly their field of application. Therefore, this manuscript explores the possibility of using laser forming to reprocess FMLs and obtain final components with precisely controlled bending radii. For this purpose, the effect of the laser operating parameters, namely laser power, scanning speed and number of passes, on the final shapes of FMLs was investigated. Secondly, further tests were also performed to obtain other complex shapes on FMLs from multiple laser scanning paths, side by side and equidistant on the substrates. An analysis of the failure of the substrates during the shaping process was also performed, with particular emphasis on deformation mechanisms, interfacial delamination and thermal alteration of the layers. The experimental results showed the good viability of laser reprocessing to shape FMLs, thus opening up new possible applications of this class of materials in aeronautical and aerospace applications.

Laboratory testing of different window design cases for noise transmission

We investigated the effect of different window designs employed in Abu Dhabi Emirate- UAE on the level of noise transmission. For that, 21 window cases were tested in the laboratory. Several factors were considered, including window glass thickness, glazing, lamination, opening style, area, frame type, frame style, and use of shutters. Results showed that sound transmission loss is improved significantly with the use of shutters and the use of hinged, not sliding, windows. The instalment of glass thicker than 6 mm did not cause any improvement. As for the double glazed windows, no noticeable improvement was detected with an air gap of 12 mm or less, but increasing the air gap to 20 mm causes a moderate improvement. Slight improvement was found when a lamination layer or uPVC frame (instead of aluminum) was used. It was further found that box umbrella and curtain wall frames did not seal as well as half umbrella frames, and thus resulted in a lower acoustic performance of the windows.

The effect of drilling parameters, cooling technology, and fiber orientation on hole perpendicularity error in fiber metal laminates

Conventional twist drilling is a widely used machining process for creating holes in aerospace and automobile structures. Drilling at room temperature can sometime affect the quality of machined holes due to increased thermal effects on the workpiece. Thermal effects can be a cumbersome when machining composites and fiber metal laminates due to their different thermal expansion coefficients, which may introduce additional stress in the structure. Thermal machining effects can be minimized using coolants supplied either directly or indirectly to the cutting tool-workpiece interaction zone, to remove away part of the generated heat. The use of coolants adds extra costs for handling, disposal, and environmental impact. Therefore, environmentally friendly cooling technologies are replacing conventional cooling methods to reduce costs and impact on the environment. In addition, the selection of machining parameters has great influence on the hole quality. This paper investigates the impact of drilling parameters and two modern cooling technologies namely cryogenic liquid nitrogen and minimum quantity lubrication on the hole perpendicularity error of fiber metal laminates commercially known as GLARE® (Glass Laminate Aluminum Reinforced Epoxy). It was also found that applying cryogenic liquid nitrogen or minimum quantity lubrication does not lead to an improvement in hole perpendicularity error in GLARE® laminates.

Simulating the impact damage of laminated glass considering mixed mode delamination using FEM/DEM

This paper presents an approach for modelling the impact breakage of the laminated glass (LG) using the combined finite-discrete element method (FEM/DEM). It encompasses the discrete crack model for glass, the Mooney-Rivlin model to represent the hyperelasticity of the PVB interlayers. The improved Xu and Needleman model is adapted to serve as the mixed-mode interfacial constitutive law, in particular, describing the combined damage-plasticity behaviour for irreversible unloading and thus can predict the interlaminar cohesion failure. The comparison between the simulation and the experimental results for several laminated glass make-ups shows that this interfacial model can adequately reproduce the typical delamination behaviour. The characteristics of the stress wave propagation and the interlayer tearing in the example cases can be satisfactorily reproduced. The shortcoming of the discrete crack model in modelling the impact damage of strengthened glass and the resulting errors are discussed as well.

Laminated glass beams with thick embedded connections – Numerical analysis of full-scale specimens during cracking regime

Laminated and hybrid glass systems are typically realized by bonding or joining together several structural components and materials. Their structural performance and safe design is hence related to the optimal combination of several parameters, including material properties and degradation, geometrical ratios, connections type and features, etc.This research paper is focused on the numerical assessment of the load bearing performance of full-scale laminated glass (LG) beams with thick embedded connections. There, the structural interaction between multiple glass segments is offered by thick metal inserts, being embedded in the LG sections during the production stage. The overall bending response of such assemblies, given the same glass beam segments, is strictly related to the connection detailing, namely including the number, position, size, etc. of embedded connectors. In this regard, Finite Element numerical models able to properly capture their actual local and global behaviour can represent a robust support for time/cost-consuming full-scale experimental investigations. Refined FE models are hence presented for selected specimen configurations, and validated towards four-point bending experimental tests carried out on LG beams with three different types of embedded connections and available in the literature.In the typical FE model, the geometrical and mechanical properties of the reference specimens are properly taken into account, so to explore both the elastic and post-cracked performance of the LG beams object of study, under specific loading conditions. Comparative results are then critically discussed, giving evidence of major structural performances for the selected configurations, and including a concise parametric study.

P‐63: Improving Peeling Force for Cover Glass Lamination to Display Panels

The peeling force requirements are very strict for achieving high quality OCA, OCR full lamination. In this paper we report a detailed study of cover glass lamination including bonding force, surface energy treatments, UV curing direction, and adhesive layer design & properties.

Bearing strength and failure behavior of pinned hybrid glass-flax composite laminates

The aim of the present work is to evaluate the influence of external layers of glass woven fabric on the pin-hole strength of flax/epoxy laminates. Single lap bearing tests were carried out to evaluate the fastened joint performances depending on laminate stacking sequence. In order to better identify the mechanical behavior of the hybrid laminate, full glass and flax laminates were also compared. In particular, bearing stress and failure mechanisms were investigated at varying joint geometry. Furthermore, an experimental failure map, clustering main failure modes of pinned hybrid composite laminate, was used to better clarify the relationship between mechanical failure and geometrical parameters of joints. The experimental results showed that the presence of external layers of glass fabric in a flax/epoxy laminate positively influences the mechanical performance of mechanically fastened joints. Furthermore, in a hybrid laminate, bearing fracture mechanism occurs for a large range of joint geometries, thus supporting the joining design of flax based composite laminates.

Effect of salt water conditioning on novel fiber metal laminates for marine applications

One of the issues with the widespread use of polymer matrix composites in marine applications is their high susceptibility to environmental degradation, particularly hygrothermal conditions. Therefore, the present research intends to contribute to the better protection of the marine polymer matrix composites through the introduction of a newly developed fiber metal laminate for marine applications. This type of fiber metal laminate consists of a marine aluminum alloy of 5083 alternating with glass fiber reinforced epoxy composite layers. In order to evaluate the characterization of the environmental durability of this novel material, the specimens made of fiber metal laminates as well as commercial woven glass–epoxy composites were exposed to hygrothermal aging and hygrothermal cycling in boiling salt water. Then, to study the structural degradation caused by exposure to salt water, the mechanical properties of fiber metal laminate and woven glass–epoxy specimens under three-point bending and impact loading were evaluated. Results show that exposure to the saline environment generally decreased the flexural strength of woven glass–epoxy and fiber metal laminate specimens, whereas a smaller deterioration in flexural stiffness of both laminate types was found. Moreover, it was observed that the hygrothermal conditioning in salt water did not affect significantly the impact properties of both the fiber metal laminate and woven glass–epoxy specimens as compared to the flexural properties.

Post-failure behavior of laminated glass beams using different interlayers

An experimental investigation is presented on the mechanical response of progressively damaged Laminated Glass (LG) beams assembled with modified polyvinyl butyral (PVB)-based interlayers (DG41). While it is known that ionoplast interlayers significantly improve the load-bearing capacity and residual strength of damaged LG elements, limited experimental data are available on recently developed compounds such as DG41. The role of interlayers increases with the damage level within LG elements: when glass plies break, LG stiffness and strength depend on the ability of the interlayer to couple intact glass plies and fragments of shattered ones. For damaged LG beams, the consequences of the increases in volume of a broken tempered glass plies are discussed. In particular, the interlayer activates two competing effects on the undamaged glass plies affecting the residual carrying capacity: a positive “tension-stiffening” over time and the tendency of tempered glass to expand when fractured that triggers “negative” stress/strain fields in undamaged glass plies.

Experimental and simulation studies on delamination strength of laminated glass composites having polyvinyl butyral and ethyl vinyl acetate inter-layers of different critical thicknesses

The laminated glasses (LGs)composites are gaining popularity as protectivestructural material. Delamination strength (DS) of (LGs) with different inter-layers and their different nominal thicknesses were compared. The effect of inter-layer thickness, delamination load, and inter-layer type on DS is clearly observed from this brief study. It is concluded that inter-layer thickness has the significant role in determining the DS of LGs. The statistical analysis confirmed the strong association of DS with inter-layer thickness and the interlayer type. It was found that the LG-PVB composite has the comparatively lower DS than LG-EVA composite and inter-layer thickness has the prominent role in the determination of DS in the LG-EVAcomposite. There is an increment in DS with an increment in critical inter-layer thickness in both LG-EVA and LG-PVBcomposites. The increment in the inter-layer thickness from 0.38 mm to 0.76 mm increases DS significantly; whereas, the further increment in the inter-layer thickness to the higher value has a lesser effect. The finite element model was constituted (without considering the effect of temperature) for determining DS of LG composite. The simulation results were in a good match with experimental results. The results of the present work can be utilized by the design engineers while selecting LG for structural applications.

Experimental and simulation studies on fracture and adhesion test of laminated glass

The present work includes fracture and adhesion testing of laminated glasses (LGs) with different inter-layers (Polyvinyl butyral (PVB), Ethyl vinyl acetate (EVA)) and their different critical thicknesses (0.38, 0.76, 1.52 mm) following the IS 2553. The fracture pattern of each type of LG sample is discussed. The finite element (FE) analysis is conducted to obtain the total deformation, equivalent stress and equivalent strain of LG samples. The effect of inter-later type and thickness on fracture pattern of LG samples, fragment size, maximum deformation (MD), maximum equivalent stress (MES), maximum equivalent principal strain (MPES) is also discussed. The statistical analysis is conducted for the validation of experimental results. The failure processes and damage characteristics of LG can be predicted /explained collectively from the results of the experimentation and simulation. The results of the present work can be utilized by the design engineers while selecting LG for structural and automotive applications.

Effect of Novel Thermo-Chemical Treatment on Bending Strength of Laminated Glass

The science of thermal and chemical treatment of glass is well documented. The Laminated Glass (LG) is usually not treated as either treated glass is used during production or lower melting temperature of interlayer does not allow the treatment. The present work reports the novel methods of thermo-chemical treatment of LG having annealed soda lime glass plies. Five thermo-chemical treatments were performed on LG using different salts (Potassium Nitrate Carbohydrazide, Lithium Nitride), via clay coating (saturated with salts), using fused silica wafer coated with a thin graphene layer and utilizing the microwave heating. The bending strength is measured before and after thermo-chemical treatment using Q-set coupled bending tester (following the ASTM D790-03). The linear elastic model is utilized for obtaining normal stress and deformation at fracture load using ANSYS 14.5. The bending strength of thermo-chemical treated LG sample was found significantly higher than untreated LG in the most cases. The fracture pattern of the treated LG was also modified compared to the untreated LG as impurities and defects were reduced during treatment. The mechanics of increased bending strength and modified fracture is also discussed with reference to the effects of thermo-chemical treatment of LG, however, the need of a specialized numerical method that can effectively model the implications of treatment on LG and multiple fractures experienced by the LG during testing are suggested as future work.

Effect of Polymeric Interlayer on Wave Propagation in Transparent Soda-lime Glass

The transparent armor and aircraft windshields are comprising of glass or transparent ceramic laminates joined with the polymeric interlayer. The interlayer thickness plays a vital role in improving the damage, impact, and wave propagation response of transparent laminates. The edge-on-impact simulations on monolithic ballistic soda-lime glass are performed first to investigate and verify the wave propagation using ANSYS/Autodyn. Secondly, to lessen the wave speed and damage area in the glass, the different thicknesses of PU interlayer were incorporated in the numerical model and analyzed. The delay time in wave arrival time as a function of interlayer thickness was estimated. Additionally, the influence of PU interlayer orientations and a number of layers (single & double) on longitudinal wave propagation and damage are also studied numerically and discussed.

Material combination to mitigation of behind armour debris after shaped charge jet attack

When a shaped charge jet perforates the steel armour plate, the residual jet is accompanied by a much wider cloud of behind armour debris (BAD) generated by stress wave interactions. BAD plays an important role in the evaluation of survivability of vehicle crew and components in a vehicle. The Behind Armor Debris (BAD) cloud caused by shaped charge jet impact was investigated. In order to simulate different configuration of material to mitigation of debris cloud the thickness of ceramics target tiles, glass and aramid laminate liners in contact with the armour plates was varied.

Characterization of Glass Laminate Aluminium Reinforced Epoxy- A Review

Due to present need of light weight and high performance structure, new hybrid materials are developed known as fiber metal laminates (FML). Fiber metal laminates comprises of alternate layers of composite and metals bonded together with appropriate adhesive technique. Mechanical and chemical surface treatment of 2024 aluminum alloy metal for obtaining strong interface bond between aluminum and composite layer. Due to decreased manufacturing cost and time, ease in forming, recyclability, thermoplastic composite are preferred in this study. Fiber metal laminates manufactured by press molding of one surface treated 2024 aluminum alloy as core material and two outer layers of glass fiber reinforced thermoplastic composite. This study investigates the mechanical properties of these fiber metal laminates by performing various tests such as tensile test, low velocity impact test, fire resistant test and flexural test. These results were further validated using analysis software.

Electrochromic materials and devices for energy efficiency and human comfort in buildings: A critical review

Electrochromic (EC) materials can be integrated in thin-film devices and used for modulating optical transmittance. The technology has recently been implemented in large-area glazing (windows and glass facades) in order to create buildings which combine energy efficiency with good indoor comfort. This critical review describes the basics of EC technology, provides a case study related to EC foils for glass lamination, and discusses a number of future aspects. Ample literature references are given with the object of providing an easy entrance to the burgeoning research field of electrochromics.