The Office of Naval Research is developing a new seat suspension system that can help protect Marines riding in ground vehicles or flying in helicopters.
The suspension system prevents some of the impact from mines or improvised explosive devices from moving through the seat and into the passenger, effectively lessening the force of the blast that reaches the body.
Additionally, it reduces the intensity of vibrations passengers in ground vehicles and helicopters feel through their seat, allowing for a more comfortable ride.
The military has used this type of suspension system in the past, but it was calibrated for men of average weight. The new devices automatically adjust to fit passengers ranging from 140 to 365 pounds. This includes the lightest 5 percent of women and the heaviest 5 percent of men, fully dressed in gear and personal protective equipment.
"This is an intelligent seat," said Robert Kargus, an engineer with the Army Research Laboratory. ONR is funding his lab's work.
When there is an under-body blast, the suspension system almost instantly adjusts the tension in the seat to match the size of the explosion and lessen the impact for passengers, Kargus said.
This suspension system is the most advanced of its kind, and it is three times more effective than its predecessors, he added.
"It's coming close to exceeding the capabilities of the vehicle," he said.
The ability to calibrate suspension systems to passengers of different weights is crucial to their effectiveness, according to a report from Techno-Sciences, a defense contractor that works in similar technology.
Old systems that were designed to fit a man at the 50th weight percentile "will fail to adequately protect occupants of varying weight with proportionally varying injury thresholds." That would leave the system falling short of adequately protecting those riding in the vehicle or aircraft from other shocks or vibrations, the report states.
ONR's system is in its fifth year of development and third prototype and will go to live blast tests by the end of the year, Kargus said. Once the system has been through tests, it'll be integrated into a vehicle to determine whether Marines can actually use it. Researchers will also compare the quality of the ride to conventional suspension systems.
Magnets play an important role in how the hardware works. Sensors are built into seats; once someone sits down, the sensors tell a computer how much resistance the suspension system should apply for the passenger.
The resistance comes from putting a slurry of iron-laced liquid into an electric field. Usually the microscopic iron fragments float in an unorganized manner in the liquid, but when they're exposed to an electric field, the iron fragments line up in an orderly fashion. This increases the viscosity of the liquid, which increases resistance in the suspension system. The seats are able to adjust the viscosity to fit each passenger, and to react to explosions.
In order to actually absorb the shock, the suspension system can move almost double time, absorbing nearly twice as much as conventional shock mitigation seats, said Jeff Bradel, manager for maneuver science and technology in ONR's Expeditionary Maneuver Warfare and Combating Terrorism Department. This increases the survivability of the passenger.
