US 20050188831 A1
A turret is rotatably mounted to the roof of a vehicle such as a HMMWV and provides ballistic protection to an individual inside. The turret wall has one or more layers of ceramic tiles set in a polymer resin reinforced with nanoparticles. A nonwoven material backs the ceramic layers to spread an impact over a larger surface area. A laminated multiply nanofiber textile layer is in back of the ceramic layers to stop fragments form penetrating through the turret wall. The nanofiber textile plies are laminated together with resin reinforced by carbon nanofibers or nanotubes.
1. A ballistic resistant turret for use on a vehicle, comprising:
a) a wall that is structured and arranged to couple to a vehicle mount;
b) the wall comprising a woven material comprising nanofibers, the woven material impregnated with resin;
c) the wall also comprising at least one layer of ceramic material bonded to the woven material.
2. The turret of
3. The turret of
4. The turret of
5. The turret of
6. The turret of
7. The turret of
8. A vehicle, comprising:
a) a roof;
b) a rotatable bearing mounted on the roof;
c) a turret mounted to the bearing, the turret comprising a wall that has a layer of woven material and a layer of ceramic material bonded together, the woven material comprises nanofibers and is impregnated with resin.
9. The vehicle of
10. The vehicle of
11. A method of making a turret, comprising the steps of:
a) providing a mold of the turret;
b) in succession applying a ceramic layer and a fragment capture layer to the mold;
c) applying the fragment capture layer to the mold by applying plural plies of woven nanofiber textile impregnated with a first resin;
d) applying the ceramic layer to the mold by embedding ceramic tiles in a second resin.
12. The method of
13. The method of
14. The method of
This application claims the benefit of provisional patent application Ser. No. 60/481,080, filed Jul. 11, 2003.
The present invention relates to armored trucks or vehicles and particularly to turrets for such vehicles.
Military vehicles, such as the High Mobility Multipurpose Wheeled Vehicle (HMMWV), the Land Rover and the Unimog, frequently have a soldier standing in the rear, manning equipment. Various equipment configurations can be used, such as a machine gun, or reconnaissance viewing optics. The equipment is typically mounted on a bearing so as to allow horizontal rotation.
This position, known as a “gunner” when the machine gun is used, is exposed to fire. A soldier in the gunner position has to rely on his personal body armor for protection.
In the prior art, attempts have been made to provide an armored turret ring of steel around the gunner's position. The steel turret ring, while improving ballistic protection, adds new dangers. HMMWV's have a high center of gravity. Adding a heavy turret ring to the vehicle raises the center of gravity even higher. The vehicle is less stable and prone to tipping. Also, adding a heavy steel ring increases the weight of the vehicle chassis, thereby producing more mechanical breakdowns.
It is an object of the present invention to provide an armored turret ring for vehicles, which ring is light in weight.
The present invention provides a ballistic resistant turret for use on a vehicle that comprises a wall that is structured and arranged to couple the wall to a vehicle mount. The wall comprises a woven material comprising nanofibers, the material being impregnated with resin. The wall also comprises at least one layer of ceramic material bonded to the woven material.
In accordance with one aspect of the present invention, the woven material containing nanofibers further comprises plural plies of woven material with each ply comprising nanofibers. The plies are bonded together with a resin that comprises nanotubes or carbon nanofibers.
In accordance with another aspect of the present invention, the resin bonding the layers together comprises carbon nanofibers or nanotubes and the woven material comprises polymeric nanofibers.
In accordance with another aspect of the present invention, the layer of ceramic material comprises ceramic tiles embedded in a resin.
In accordance with another still aspect of the present invention, the layer of ceramic material further comprises ceramic tiles embedded in a resin that is reinforced with nanoparticles.
In accordance with still another aspect of the present invention, the turret comprises an energy absorption material interposed between the woven material and the ceramic material.
The present invention also provides a vehicle that comprises a roof and a bearing mounted on the roof. A turret is mounted to the bearing, with the turret comprising a wall that has a layer of woven material and a layer of ceramic material bonded together. The woven material comprises nanofibers and is impregnated with resin.
In accordance with one aspect of the present invention, the woven material comprises polymeric nanofibers and the resin comprises carbon nanotubes or carbon nanofibers.
In accordance with another aspect of the present invention, the ceramic layer comprises ceramic tiles embedded in resin reinforced with nanoparticles.
The present invention also provides a method of making a turret comprising the steps of providing a mold to the turret and successively applying a ceramic layer and a fragment capture layer to the mold. The fragment capture layer is applied to the mold by applying plural plies of woven nanofiber textile impregnated with a first resin. The ceramic layer is applied to the mold by embedding ceramic tiles and a second resin.
In accordance with one aspect of the present invention, the step of applying plural plies of woven nanofiber textile impregnated with a first resin further comprises applying plural plies of woven nanofiber textile impregnated with a nanotubes or nanofibers reinforced resin.
In accordance with another aspect of the present invention, the step of embedding ceramic tiles in a second resin further comprises the step of embedding ceramic tiles in a nanoparticle reinforced second resin.
The turret 13 provides a ballistic resistant wall around the upper body of the gunner 15. The turret 13 provides protection against direct gunfire (such as a bullet striking the turret wall), up to National Institute of Justice (NIJ) level IV protection, and also protection from fragmentation ballistic particles (such as shrapnel). In the preferred embodiment, the turret weights no more than 160 pounds in order to maintain the vehicle center of gravity as low as possible. The vehicle can be provided with other armor to protect the gunner's lower body, as well as other occupants of the vehicle.
As shown in
Coupling brackets 29 and a hatch door 31 are mounted to the turret wall by conventional fasteners, such as screws. The coupling brackets 29 mount to the bearing ring 17.
The size and shape of the turret 13 is dictated by the particular vehicle that is to receive the turret and can therefore vary.
The laminated woven material 41 is made up of several layers of textile 51. The textile is made up of polymeric nanofibers. In the industry, “nanofibers”, “nanotubes” and “nanoparticles” are taken to mean fibers, tubes and particles, respectively, that are 1,000 nanometers (nm) or less in diameter. The length of the nanofibers and nanotubes can be much longer than 1,000 nanometers in length, but the diameter is small. The nanofibers and nanotubes are obtained from conventional processes.
In the preferred embodiment, the polymeric nanofibers are PBO (polyphenylene benzobisoxazole or polyphenylene benzobisozazole). Other types of polymers could be used such as aramids, cellulose acetate, polypropylene, etc. The nanofibers are made up of the core structure of the polymer, namely fibrils, which are the molecular polymer chains. The nanofibers have the essence of the polymer structure that provides the mechanical properties of that polymer. When woven into a textile, the result is a very strong material that is light in weight.
The polymeric nanofibers are converted into linear assemblies (yarns). For example, one process of forming a yarn involves spun bonding where a polymer that has been dissolved in a solvent is applied to the nanofibers during spinning. The yarn is then woven into a textile. In the preferred embodiment, the textile is woven in a plain weave of 545 Dtex and 500 denier. In the preferred embodiment, the laminated woven material layer 41 has 30 plies of the nanofiber textile.
The plies are laminated together by impregnating each ply of the nanofiber textile with a phenolic resin 53. The resin is conventional and commercially available under names such as Georgia Pacific's GP-445D05. The resin is impregnated with carbon nanofibers tubes or carbon nanotubes. In order to disburse the carbon nanofibers or nanotubes in the resin, the nanotubes are first disbursed in a solvent, such as acetone. The solvent is then mixed with the resin. The solvent evaporates and disburses the nanofibers or nanotubes inside of the resin. The amount of carbon nanofibers or nanotubes relative to resin can vary between 1-50% by weight. In the preferred embodiment, 1 to 5% nanotubes by weight to the resin are used.
The resin impregnates the individual plies, which are then laid on each other to form the laminated woven material layer 41. In the preferred embodiment, an inside mold is made for the turret ring. The plies of polymeric nanofiber textile are laid up on the outside of the mold. Ply rotation can be used, but is not thought to be critical. The plies are put onto the mold so as to be flat. The pieces of textile are cut into shape to preserve the flatness and prevent wrinkles. The edges of the textile pieces can overlap and need not be stitched together due to the bonding provided by the resin. Once all the plies of the nanofiber textile have been laid up on the mold, the resin is then cured. In the preferred embodiment, the resin is cured for 30-60 minutes at 30-50 psi and 250-350 degrees Farenheit.
The polymeric nanofibers are between 100-700 nanometers in diameter, while the carbon nanotubes are between 1-20 nanometers in diameter and the carbon nanofibers are between 30-300 nanometers in diameter. The polymeric nanofibers are more elastic than the carbon nanotubes. The carbon nanotubes/nanofibers are stiffer than the polymeric nanofibers and enhance the inner-laminate strength between the plies. Carbon nanotubes are preferred, although at present, the cost is very high so carbon nanofibers are used. It is predicted that the cost of nanotubes will drop. Carbon nanofibers are used in higher concentrations than carbon nanotubes. In this description, “carbon nanotubes” are used interchangeably with “carbon nanofibers”. The nanofiber textile is strong, yet flexible, and resistant to penetration.
The next layer 43 is the non-woven material. In the preferred embodiment, the non-woven material is PBO. Nonwoven PBO is a felt-like material and is commercially available under the name Zylon. Multiple plies of the PBO are applied to the outside of the laminated woven material layer 41. Each ply of PBO is bonded to the underlying ply by a tackifier, which is commercially available. The tackifier is allowed to set before applying the next layer 45. 20-40 plies of PBO are used in the preferred embodiment.
Bonded to the outside of the non-woven material layer 43 is the ceramic layer 45. The ceramic layer 45 is made up of individual ceramic tiles 55 that range from 0.75 to 1.0 inches in diameter and are 0.125 inches in thickness. The ceramic tiles are alumina or silicon carbide. The tiles are imbedded in a polymer 57. The polymer is a phenolic resin, such as the commercially available Ren-Lam. The resin is reinforced with silicon dioxide nanoparticles, which are between 20-800 nanometers in diameter. Nanofibers or nanotubes could be used, but are harder to disperse in the resin. The nanoparticles are dispersed in the resin by first suspending the nanoparticles in a glycol solution, which solution is then mixed or blended with the resin. The amount of nanoparticles to resin can vary between 10-50% by weight. In the preferred embodiment, the amount is 20% by weight. The glycol evaporates from the resin leaving the nanoparticles in the resin. The resin is spread onto the underlying layer and the ceramic tiles are then laid onto the resin. More resin is applied to the spaces between the tiles and to the outside of the tiles. The resin is then cured for 24 hours at ambient temperatures.
The inner ceramic layer 45 is encased in another non-woven material layer 47, which is substantially similar to the layer 43, and an outer ceramic layer 49, which is substantially similar to the ceramic layer 45.
The turret wall is then removed from the mold and the inside and outside surfaces, along with the upper and lower edges, are coated with an anti-ballistic coating 51. In the preferred embodiment, the anti-ballistic coating is polyurethane with reinforced aramid fibers 59. The fibers are very small, on the order of 10 microns in length. This coating is sprayed on hot, at about 400 degrees Fahrenheit.
When the turret 13 is finished, the wall is 0.75-1.25 inches in thickness.
After fabrication, the mounting hardware is secured to the turret wall by suitable fasteners. The turret is then installed on the vehicle, and in particular to the bearing ring 17. The turret is light enough that two people can install it onto a vehicle in a short period of time and without the use of any special tools. For example, a lift need not be used.
In operation, the turret can rotate in conjunction with the machine gun 19. If fired upon, projectiles or ballistic particles hit the outside ceramic layers 49, 45 first and are slowed down. The non-woven material layers 47, 43 are energy absorbing layers and spread the impact load on an individual ceramic tile over a much larger area. The impacting projectile will typically break apart in to smaller fragments. The resin in the ceramic tile layers 45 and 49 is reinforced and toughened by the nanoparticles. Any particle fragments that pass the ceramic layers 49, 45 and the other layers 47, 43, are then captured by the laminated woven material layer 41 and are prevented from completely penetrating the wall into the gunner's position. The nanofiber textile provides a strong barrier to ballistic particles. The resin that laminates the nanofiber textile plies is reinforced by the nanotubes.
Depending on the desired threat protection, a variable number of plies and layers can be used. For example, in the preferred embodiment, there are 30 nanofiber textile plies in the laminated woven material layer 41. However, fewer or more plies can be used. Also, the preferred embodiment has two layers of ceramic. More or less ceramic layers could be used.
The turret is manufactured in such as manner as to achieve a seamless outer barrier that provides the maximum ballistic protection. By incorporating highly advanced materials and unique and novel manufacturing processes, the turret derives its ballistic resistance from the inner-relation and interaction between the included materials in a lightweight conformable assembly. The turret is resistant to moisture, ultraviolet light, has a wide operating temperature range (−40 degrees Fahrenheit to 155 degrees Fahrenheit), is impact and scuff resistant and has a areal weight of approximately 6 pounds per square foot in order to comply with NIJ level 3 standards. Due to its scalability, both in materials and process selection, the turret can be made to provide NIJ level 4 protection at an areal rate of approximately 10 pounds per square foot.
In addition, the turret 13 is light in weight. In the preferred embodiment, the turret weighs under 160 pounds. As can be seen in
Although the present invention has been described as being made from the inside out, the manufacturing process could be reversed, where the layers were built on a mold from the outside in.
The foregoing disclosure and showings made in the drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense.