Akron, Ohio - Getting a flat tire is never convenient. In a war zone, it can be deadly and very dangerous. While special operations vehicles have been loaded with extra armor to protect troops in Iraq and Afghanistan, the tires remain vulnerable to attacks by improvised explosive devices (IED). The unique carbon fiber multiple hoop tire design by American Engineering Group may be the key to a new Zero Pressure Tire that could keep military vehicles running faster and longer after an attack.
Akron based American Engineering Group (AEG) has received a $1 million Phase II project grant from the US Department of Defense (DOD) to develop a tire that will continue running even after being shredded by roadside bombs or gunfire. Though military vehicle tires are now equipped with run-flat inserts, the DOD wants to upgrade to a zero pressure tire that's better at carrying heavier loads and can quickly move soldiers out of harm's way.
When engineers at American Engineering Group began working on tire designs, they settled on a flexible multiple carbon fiber hoop structure - which functions like air inside a tire. Along with carbon fiber multiple hoops for strength, the design allows shrapnel and high-caliber bullets to pass through the tire. During project phase I testing in 2011, the tire continued to run well - keeping the same functional road performance - even after receiving several rounds of gun shots.
Zero pressure tires have been around for a long time, with major drawbacks such as bumpy rides and overheating. The American Engineering Group (AEG) prototype dissipates heat and has the tire flexibility and strength to support the heavy military pick-up weight while providing a relatively smooth ride.
Though military vehicles outfitted with "run-flat" tires are supposed to travel at least 30 mph for 30 miles (the minimum DOD requirement), field performance of current run-flat tires hit by roadside bombs were reported to be much lower than this minimum requirement. The new AEG Zero Pressure Tire will withstand a minimum of 50 mph speeds for 300 miles once it's punctured based on results from Phase I completed studies in 2011.
"This level of load carrying capability and survivability surprised even me" says Dr. Jon Gerhardt, one of the designers.
Defense vehicle weight requirements are increased so much that the current tires can not support the load. DOD wants to create a tire that extends the mobility of the vehicle as well as the survivability and maintainability. AEG personnel fired a very large-caliber round with a high-velocity rifle into the tire several times. The damaged tires performed well and could perform at 50 mph speeds for 300 miles. The durability characteristics of this design will be studied further in this Phase II on four different tire sizes from four different DOD Special Operations Vehicles.
Carbon Fiber Hoops
In a 5,000-square-foot lab in Akron, Ohio, American Engineering Group works on different combinations of polymeric elastomeric materials to make the multiple carbon fiber hoops that are bonded to the carcass of the tire.
Finding the right combination of hoop dimensions and materials is the challenge. A softer material provides good durability and flexibility but wears out sooner. A harder material lasts longer but also generates more heat.
Road testing
Eventually, Zero pressure tires will be tested by the military at Proving Grounds to demonstrate results of mine blasts and handling during obstacle encounters. Since the tire is still under development, there's no price tag. AEG is expected to develop a tire that costs the same or less than current military tires.
"AEG's motivation and driving force for this project are that AEG gets the privilege to be of help to save lives of our soldiers" according to Abraham Pannikottu, Operations Manager at AEG.
For more info, visit http://www.engineering-group.com