Patent Application
20120255428
1. Field of the Invention
The present invention relates generally to the field of armor for the protection of passengers of a military vehicle. The invention relates more specifically to a blast shield for the bottom surface of military vehicles to protect passengers against IEDs.
2. Background Discussion
The wars in Iraq and Afghanistan have shown that our military vehicles need a re-design to the bottom of the vehicle to protect against the new threat of Improvised Explosive Devices (IEDs). One of the first “V” shaped blast hull designs was used by the South African military in the 1980's. It was specifically designed to maximize passenger survivability for conventionally laid mines. The V-shaped hull is designed to redirect the blast out and away from the vehicle's passenger area. The vehicle may be disabled by the IED, but passengers will survive the blast.
It is easy to design a new vehicle with V-shaped blast shield. All of the new MRAP vehicles, (Mine Resistant Ambush Protected) are equipped with a V-hull and most new military vehicles coming out today from all suppliers have them. A large problem is attaching the V-shaped blast shield to vehicles that are already in service. One such vehicle is the Humvee which rides close to the ground and has a flat bottom. There are over 16,000 armored Humvees in Iraq today with over 100,000 Humvees worldwide. Their flat, low bottom surface makes them vulnerable to the IEDs. Today the military is adding armor to the sides, but no blast protection is being added to the flat bottom of the vehicle.
In the present invention, a manufacturing process is implemented to build a V-shaped blast shield that could be attached to a vehicle bottom. This may be applied to a new vehicle or one that's already in service.
Tests were conducted to determine the best manufacturing process to be used when the V-hull was exposed to the mine blast forces. The investigation included Mig Welding, Friction Stir Welding (FSW) and adhesive bonding with bolts.
The following results were recorded; welding was compared to FSW on joining two blast shields together. The test results show that welding was the weakest method at about 83% below baseline and FSW was about 26% lower than the baseline samples. The baseline test uses a panel without any joining methods applied.
On a second set of test Mig Welding on two surfaces was compared to applying an adhesive to three (3) surfaces. In this test, a sample was fabricated for each method and then compression tested to failure. The adhesive joint was twice as strong as the welded samples. A retest with the welded sample was done to make sure of the data and the results were the same. It was noted that when the adhesive joint had failed, it was immediate, and there was no strength remaining in the joint. After seeing this, it was decided that the adhesive joint, along with a high strength bolt, was needed to survive the blast force. Also, a tapped blind bolt hole is a flat bottom hole used to prevent any secondary projectiles from entering the cabin. To form the V-shaped hull when using flat panels of blast resistant material, an I-beam is machined or extruded to form the needed V-hull with an I-beam. The I-beam channel opening is configured to have between 0.020″-0.030″ oversize to the thickness of the flat plates that are installed. The oversize is the receiver for the adhesive. The receiving channels in the I-beam for the flat blast plate have an obtuse angle between the plates that would allow the plates to clear the bottom of the vehicle to make the V-hull. Then, a number of threaded holes with flat bottoms are employed. The adhesive used was from ITW Plexus. Any adhesive with the same mechanical properties could be used. The blast plates used for this test were from Cellular Materials International (CMI) Micotruss™. Any blast plate material could be used with this invention. This manufacturing process could be used for new vehicles or as an upgrade to flat bottom vehicles.
Many blast shield materials may be limited in size. To overcome this, a coupler sleeve may be used to join parts together for adhesive joining. The same manufacturing method described above can be used to increase the width of the blast shield. The only difference is that the receiving channels in the I-beam, coupler sleeve, are at 90 degrees to the top and bottom surfaces.
The inventive structure was used to build a test blast shield and then tested in a blast. This test was successful where the glue joint stayed intact, and the I-beam did not fail during the blast and no secondary projectiles entered the cabin.
The aforementioned objects and advantages of the present invention, as well as additional objects and advantages thereof, will be more fully understood herein after as a result of a detailed description of a preferred embodiment when taken in conjunction with the following drawings in which:
Referring to the accompanying figures and to
The invention herein relies in part on maintaining the loading integrity of these blast resistant panels by avoiding the use of welding and instead relying on adhesive to affix the panels into the channels of the I-beam. As shown schematically in
In those instances where the blast plates are not sufficiently wide to accommodate both the angle of the V-shape and the full width of a vehicle, the configuration of
Finally,
It will be understood that the invention disclosed herein is not to be limited by the illustrative embodiment described, but only by the appended claims and their legal equivalents.
