In order to increase the life of the armored glass, users must use special measures in difficult environments. In the photo, armored vehicles M-ATV in Afghanistan
The need for better situational awareness, which has emerged along with the combat missions of asymmetric combat operations, in which military units must move in a civilian environment and avoid indirect losses, has led to a sharp increase in the number of military vehicles with large armored glass, allowing the driver to have a much better view. the surrounding area, and the soldiers sitting in the aft compartment have a better understanding of the local situation
Although protection was the number one priority, all Mrap (Mine Resistant Ambush Protected) vehicles were equipped with wide glass surfaces. But, despite the fact that windshields also began to be installed on some new cars falling into the combat category, they were still limited in size. With the increasing levels of protection, mass, transparency and distortion have become a problem. For the same level of protection, standard armored glass has a surface density four times that of armored steel - an issue that must be considered at the design stage. The dimensions of transparent armor are also increasing, which creates certain problems, especially where new technologies are applied. In some armies, it is believed that in a light patrol vehicle, a two-pane windshield with a B-pillar gives it an aggressive look and therefore prefer a one-piece windshield. In addition, since many vehicles are currently manufactured with a basic level of protection, they must then be upgraded by installing additional armor kits. This means that they must also include appropriate upgrades to the transparent protection, which of course poses a huge problem with the prevailing method of screwing glass panels onto bolts.
The mass of stronger windshields and side windows is not only a negative factor, compared with opaque armor, the thickness also increases significantly, not to mention the deterioration of optical properties, since with increasing thickness, light transmission tends to decrease and distortions increase. Given the growing market and demand over the past few years, armored glass manufacturers have worked hard to solve the mass-protection puzzle. This has been achieved by improving the performance of standard laminates (laminates) and exploring alternative materials such as transparent ceramics. In addition to the fact that some manufacturers are quite successful in finding the optimal ratio of density-protection-visual qualities, they see transparent protection as an ideal environment that can present large amounts of information to the driver and possibly even other passengers of the car. They were inspired by aviation head-up displays - an interesting solution that could help improve ergonomics and reduce workload.
Recent missions in areas with large temperature fluctuations (as a result of a large difference between the outside temperature and the temperature of the air-conditioned cabin), with sandstorms, etc. have a significant impact on transparent armor with dire consequences for its service life. Given that ground vehicles cannot compete with aircraft in terms of maintenance costs, this cost should be kept as low as possible and should be part of the equation along with weight and performance. Vehicle operators should of course also have to take steps to protect parked vehicles, as well as follow specific cleaning techniques for the armor glass. Maintainability also plays an important role in reducing the cost.
In order to improve the performance and reduce the weight of its transparent armor, the German company Schott uses the patented borosilicate glass Borofloat, which has very good optical characteristics.
Trends
The purpose of this article is not to review the products of all manufacturers of transparent armor around the world (and their number is growing every day. For example, in October 2013, the Mexican Secretariat for National Defense announced the creation of another factory for the production of armored glass), but a desire to outline the latest trends in this area. Most manufacturers look to both the civilian and military markets. The largest of them are American Glass Products (factories in Colombia, Brazil and Peru) and French Saint-Gobain Sully. There are also many companies in the US in this area, such as PPG Aerospace, which makes transparent armor that meets Stanag standards (typically levels 1 to 3) and US ATPD 2325P (levels 1 to 3).
Another major player in the transparent armor arena for the military is the German company Schott. In addition to production in Germany, which produces armor glass in accordance with Stanag, the company also has a branch in America that produces glass in accordance with US standards, but independent of the International Arms Trade Regulations. The current European military product is Resistan, which ranges from level 1 to level 4 of Stanag 4569 and in which the identification number indicates the thickness in millimeters. Schott uses high quality Borofloat 33 borosilicate glass with outstanding properties in its transparent protection products, which allows 12-15% weight reduction compared to silicate glass while maintaining optimal optical performance.
In 2013, three new types of glass were introduced, corresponding to levels 2 and 3 of the Stanag standard. For Tier 2 applications, NY 52 BF armor glass was developed through design and lamination optimization and is designed for machines operating in normal temperature conditions from –32 ° C to + 49 ° C; the material has a surface density of 112 kg / m2 and guarantees a light transmission of 86%. The glass was fired with a 20mm single FSP fragmentation projectile at a speed of 630 m / s and universal armor-piercing incendiary bullets (API) 7, 62x39 mm. The density of NY 58 BF glass is 124 kg / m2, which is about 10% higher than the density of NY 52 BF (the mass and thickness increased accordingly), however, it has a larger operating range (up to + 75 ° C) and has been tested against fragmentation munitions with a higher initial speed (700 m / s) and more powerful armor-piercing incendiary bullets 7, 62x51 mm.
OSG's Digital Visual Window technology (top) can integrate a digital display into armored glass without compromising protection, while Silk-light technology (two pictures below) allows short warning messages to be embedded in the windshield
There are two new Tier 3 products available on the market. They allow a significant reduction in weight compared to the previous type of NY 92 BF glass, which is qualified for high temperatures and is definitely stronger, since at an areal density of 195 kg / m2 it can withstand a 20 mm FSP projectile with a speed of over 1250 m / s, as well as 7, 62x54R API, 7, 62x51 API and a regular bullet 12, 7x109. The new NY 80 BF model has a density of 174 kg / m2 (10% reduction), although the tests did not include 12.7 mm bullets, while the NY 69 BF comes with a density of 153 kg / m2 (22% less than NY 92) and it was only tested against API 7, 62x54R. For Level 4, Schott offers two grades of glass from its Resistant family. These are NY135 with a density of 284 kg / m2 and NY 194 with a density of 398 kg / m2. Both withstand a 20mm FSP projectile at speeds in excess of 1550 m / s and 14.5x114 API cartridge, although the thinner glass is tested for only one hit, while the thicker glass has multi-impact characteristics. According to Schott, NY 194 is the only glass approved and a certified solution corresponding to level 4, since it was certified by the German arms office BAAINBw (formerly BWB). The Resistant catalog includes many other products, the VPAM family complies with EN 1063 and VPAM BRV 2009 standards, and the DV family with ATPD Revision T standards. recently repurposed its flat laminated glass plant into a fully integrated line that also includes bending radius 500-1000mm and bending.
Israeli company Oran Safety Glass has developed Adi technology, which eliminates the internal anti-splinter polycarbonate layer, which, according to OSG, doubles the life of the glass.
Looking to the future, Schott is scrutinizing new materials such as transparent ceramics and spinels (a group of natural and artificial minerals in the complex oxide class with high hardness). Given the tough road regulations in Germany, the company believes that the optical performance offered by such alternative materials cannot be accepted for windshields, but due to their light weight, they could be well suited for side windows. However, the cost of such innovative materials has yet to be determined. With regard to classic laminated glass, Schott experts believe that the technologies currently available will not allow any improvements in the coming years. Such glasses have approached their limit corresponding to level 3, which corresponds to a thickness of about 75 mm and an areal density of 160 kg / m2. Schott North America specializes in glass ceramics, polycrystalline materials made by controlled crystallization of a glass base, mainly through heat treatment. During processing, a crystallized surface layer 35 nanometers thick is created, while the rest of the ceramic is 80% crystalline. This material does not provide any weight savings, but complies with American ATPD-235 standards (although the results obtained remain classified).
Another key player in the field of armored glass is Oran Safety Glass (OSG) of Israel, the only supplier to the Israeli army. The company supplies flat and curved armored glass to first-tier countries such as the USA, France, Germany, Italy, etc. OSG is particularly focused on the US market, although its armor glass is on two of the three JLTV vehicles. To achieve this goal, the company, which has two factories in Israel, established its OSG Inc office in Virginia. OSG is certainly striving to reduce weight for a given level of protection, but it is also aiming to further develop, combining different technologies in its products with the aim of adding "bells and whistles" such as defrosting to improve visibility for 30 seconds at -42 ° C.
Using semi-exotic materials, OSG has recently developed a 170 kg / m2, 83 mm thickness solution for Level 3. the effects of conditioning. OSG also offers its Crystallized Material (CM) technology, which can reduce weight by 30 to 50% (see table) with a thickness reduction of 40 to 60%. Of course, the reduction in weight in this case is more significant, since it is necessary to take into account the reduction in the weight of the glass frame itself. Here the problem is not only technical, but also economic, since ceramic-type glasses are much more expensive than standard bulletproof glass.
Crystallized material technology allows OSG to produce transparent armor at three times the cost of its laminated glass counterparts. The Israeli company has also developed two new technologies to improve the performance of laminated glass. The first, designated Rock Strike Glass (RSG), is designed to prevent the inner glass layers from breaking apart in the event of low velocity debris such as gravel and stones. This not only allows the driver to continue driving with minimally impaired visibility, but also in most cases the glass does not require immediate replacement, which saves time and guarantees a greater availability of the fleet. Since there are no standards related to this problem in the military sphere yet, OSG took as a basis the French railway standards, according to which a conical object with a diameter of 90.5 mm and weighing 20 grams after impact at a speed of 40 m / s should not cause any damage. These figures for military use have been increased to 140 m / s; As a result, OSG RSG glass showed resistance to multiple impacts at speeds of 160 m / s.
Transparent armor from the German company GuS. The company has supplied transparent surfaces for German Dingo machines in Afghanistan and is currently considering switching to ceramics.
Another technology called “Adi” (Hebrew gemstone) was shown at DSEI 2013. Today, typical laminated glass has a polycarbonate inner layer that prevents debris from spreading inside the machine if it hits the glass. According to OSG, the bonding of glass and polycarbonate accelerates delamination, and polycarbonate can also be damaged from improper use or cleaning. The statistics provided by the company show an expected lifespan of three to five years for conventional clear glass in the field. Adi technology will provide anti-splinter performance without polycarbonate, plus double the lifespan. OSG has been working on this technology for over two years. The last ballistic tests were carried out in the fall of 2013, and the production of glass using the Adi technology began in 2014.
OSG is also working on the use of glass surfaces for illustrative purposes. Silk-light technology allows you to create an integrated light-controlled electronic system that makes it possible to demonstrate simple (mostly emergency) messages directly on the armored glass. Also, the Digital Visual Window technology allows the LCD display to be integrated into transparent armor without compromising the level of protection, thus saving space in the car. The display is linked to a separate electronic unit that can be easily repaired or replaced.
Glas und Optik GmbH, better known as GuS, is another major German manufacturer. In early September 2013, the German BAAINBw qualified the new laminated glass to Level 3; its density was reduced from 215 to 170 kg / m2 (-20% of the mass) and its thickness from 91 to 83 mm, at the same time the operating temperature range was increased from –32 ° to + 49 °. In addition, its multi-impact performance was tested on a triangle with a 120mm base instead of the usual 300mm and the footprint was very small, so the impact on the back polycarbonate sheet was much reduced. As the sole supplier to the German army, GuS showed its repair capabilities in Afghanistan, where stones damaged about 3,500 windshields (more than 600 Dingo machines were deployed there), many of which were repaired by the company's working group. In the field of transparent ceramics, GuS also conducts many research programs with the German company CeramTec GmbH. While the level of protection does not seem to be a major concern, the company faces obstacles in German road traffic regulations, as the adhesive bonding ceramic tiles produces visual effects that have yet to be judged in terms of eye fatigue, headaches and disorientation. GuS is currently working closely with BAAINBw to analyze side effects before moving on to ceramics.
At DSEI 2013, Jenoptik presented a transparent plastic protection. It is heavier and thicker compared to laminates, but has the advantage of not distortion when bending.
The German company ESW GmbH, a division of Jenoptik Defense & Civil Systems, showed at DSEI 2013 transparent plastic armor, which guarantees light transmission over 90%. One of the biggest advantages of the Jenoptik solution is that the windshield can be bent; this allows you to get away from the central pillar, typical of military vehicle windshields, consisting of two flat panels of bulletproof glass, and thereby provide maximum visibility. In addition, the plastic transparent Jenoptik protector does not create any distortion, even at the bending points. The company currently offers two types of surfaces, respectively with protection levels 2 and 3. The first has an approximate density of 144 kg / m2 and a thickness of 121 mm, and the second has a basis weight of 238 kg / m2 and a thickness of 201 mm. The Level 3 solution is also certified to resist multiple bullet hits and projectile charges in the 0 ° to 45 ° sector and to resist RPG-7 hits at an angle of 45 °. Anti-icing and electromagnetic protection are available upon request. According to Jenoptik, its clear plastic bulletproof glass is capable of maintaining good visibility even after impact.
One of the authoritative European experts in the field of transparent armor is IBD. It was clear that a solution had to be found to reduce the weight of the transparent armor. Indeed, conventional armored glass for a 3 m2 truck not only weighs 600 kg, but also raises the center of gravity and catastrophically degrades stability. Adopting its NanoTech technology, IBD has developed a transparent ceramic protection, a key factor here is the development of special processes for bonding ceramic tiles ("mosaic transparent armor") and laminating these assemblies with strong carrier layers to form large transparent panels.
IBD Deisenroth has developed transparent ceramic tiles and bonding technology to create a transparent armor that saves up to 70% weight compared to traditional laminated glass. The photo shows comparative samples of rolled homogeneous steel, conventional ceramics and the new material IBD NANOTech, presented at Eurosatory 2014
ArmorLine manufactures spinel - a polycrystalline material that allows you to reduce weight and thickness. It is used in multi-layer transparent armor
Thanks to the outstanding ballistic characteristics of the ceramic material and the elastic absorption of residual kinetic energy, the company was able to obtain transparent armor panels with a significantly reduced mass. Compared to the density of 200 kg / m2 of standard bulletproof glass corresponding to Stanag 4569 level 3, the new technology allows to reduce the weight of transparent ceramics for the same level 3 to 56 kg / m2. This represents a gain of 72%, which in absolute terms would mean 170 kg for the windows of a truck taken as an example. According to IBD, the optical properties of the new transparent ceramics are at least as good as those of traditional laminated armor glass, as they are less tinted and exhibit less diffraction, and the edges of the glued tiles are completely invisible. These optical properties also extend to the infrared spectrum, meaning that night vision goggles can also be used. One NATO country was faced with the challenge of choosing reduced protection or adding another front axle for its trucks, but IBD's solution can either keep the single axle configuration and save money, or double the number of axles and increase protection. According to IBD, its transparent ceramic shielding is fully qualified and is currently in the production phase, where the optimization process is focused on cost reduction; the company's goal is to obtain a product at only 50% more expensive than standard glass. However, at the moment it is believed that it is possible to achieve a cost that is two times lower than the cost of the current solution.
Multi-layer 400x400mm transparent protection made with ArmorLine spinel after six shots. The company hopes to start making a half-size windshield by the end of 2014.
The American company ArmorLine, part of the Defense Venture Group, has developed optical spinel ceramics that allow the fabrication of transparent armor with significant weight savings. Spinel from ArmorLine is a polycrystalline material that is extremely hard and durable; characterized by abrasion resistance, which is typical for ceramics, it guarantees light transmission in the range of 0.2 - 5.5 microns. This makes it possible to use it in the ultraviolet (0.2-0.4 microns), visible (0.4-0.7) ranges, the near-IR region of the spectrum (0.7-3) and the mid-IR region of the spectrum (3- 5). That is, it can be used in military applications not only as a transparent armor, but also to protect sensors. The advantage of the ArmorLine spinel is that it can be used to produce panels of dimensions that are definitely larger than those of transparent ceramic panels. The current large panels measure approximately 70 x 50 cm, the company intends to begin production of 85 x 60 cm panels, both flat and curved (with a bending radius of 2500 mm) within a year, and ultimately to the production of flat panels 100 x 75 cm, which is half of the windshield.
The ability to supply curved transparent protection is seen as an advantage over other systems, allowing designers to implement more flexible solutions. Transparent protection based on spinel, which replaces several layers in laminated glass, has increased multi-impact characteristics and reduced weight and thickness by 50-60%. As an example, let's take laminated armor glass that can withstand a single 12.7x99 mm armor-piercing bullet hit. It has a thickness of 103 mm and an areal density of 227 kg / m2, while the spinel from ArmorLine reduces these values to 49 mm and 100 kg / m2, in other words, by 53% and 56%, respectively. This data is confirmed by looking at the transparent armor ATPD 2352 Class 3A, in which the thickness is reduced from 112 to 52 mm, and the areal density from 249 to 109 kg / m2. However, ArmorLine does not deal with multilayer materials, that is, in these cases, the masses are given for non-optimized test samples and can be further optimized. In Stanag terms, the areal density achieved for Tier 2 transparent materials is about 69 kg / m2, while for Tier 3 (armor-piercing incendiary bullet 7, 62 x 54R B32) it rises to 84 kg / m2.
The Italian company Isoclima supplies Iveco with most of the armored glass for the LMV Lince; The picture shows the glass after shelling at the Nettuno shooting range
Among the technologies used to increase the strength of transparent armor, Isoclima has developed an encapsulation method that guarantees the maximum service life of its laminates.
The Italian company Isoclima began work on transparent armor in the early 1980s for the civilian and military markets and has since developed its own proprietary technologies to optimize the laminating of glass and polycarbonate. She provided most of the transparent protection solutions for Iveco DV LMV, which were tailored to the requirements of the different customers of this light multi-purpose 4x4 vehicle. For example, the transparent armor adopted for Russian LMV vehicles is capable of withstanding temperatures from -45 ° C to + 70 ° C, the interfacing of different materials is a key element here, since the thermal expansion coefficient of polycarbonate is eight times the coefficient of glass expansion. Among its products we can find a solution corresponding to Stanag level 2, with a thickness of 58-59 mm and an areal density of 125-130 kg / m2, and a solution corresponding to level 3, with a thickness of 79-80 mm and a density of 157-162 kg / m2; all values are based on standard temperature limits.
The company is currently considering new solutions that increase performance while reducing weight. The company is testing new materials such as spinel and others, although management is convinced that the improvements lie in complex solutions, that is, improving the characteristics of glass and laminates such as films, will allow Isoclima to improve its position in the market. The company has also developed solutions to improve the lifespan of the transparent protection, such as an anti-scratch treatment on a polycarbonate backing and a patented magnetically fixed outer layer that protects ballistic glass from stone damage known as Antistone Protection Solution (AspS). The removable protective layer is based on a double-sealed magnetic gasket holding the outer protective layer made of outer glass and inner technopolymer; an air gap is created between this layer and the transparent armor. All possible drawbacks were taken into account and verified, that is, condensation, optical distortion, etc., tests showed the minimum influence of these factors on the characteristics of transparent protection. On the other hand, AspS technology significantly reduces maintenance and extends the service life of transparent armor. Many of the solutions developed by Isoclima are based on the company's participation in the design of modern transparent protection systems for the aerospace industry.
