In recent history, a major concern for military vehicle seating suppliers has been the seat’s performance in the event of a mine blast. Many of our soldiers have been severely injured or killed in this scenario, and military design engineers are working to prevent these tragedies by equipping their vehicles with seats capable of preventing spinal or brain injury under these attacks. MGA Research has worked with many different military seat suppliers in testing for seat safety during mine blast simulation using our drop tower. This testing has helped our military customers develop energy absorption (EA) technology which is currently being used in the field. This testing is very useful, but we think vibration testing would prove to be equally as important. Vibration testing could prove to be a useful method of determining the structural integrity of the energy absorption mechanisms when exposed to stress in directions other than vertical. Our drop tower tests were conducted on new production seats, which raises an interesting question: would the seats perform nearly as well after the combat vehicle has been exposed to the rough terrain conditions seen in Afghanistan or Iraq?
Following a series of mine blast simulation tests, MGA developed an experimental vibration test for an un-tested military seat. This test was developed from a generic 6-axis rough road simulation profile. The military seat was secured to the surface of the Multi-Axis Simulation Table (MAST) which is a rig powered by six hydraulic actuators that is used to match 6-Degree-of-freedom (6-DOF) acceleration data. The seat was occupied with a dummy representative of a soldier equipped with their gear, and this dummy was secured to the seat. Throughout the duration of the test, we observed several occurrences of structural issues. We consulted the mine blast simulation engineers and discovered that we produced similar failures, as well as some new failures.
Vibration durability test setup on a 6-DOF MAST system
Moving forward, we would like to work on developing a better representation of a 6-axis military vehicle simulation by collecting data from such a vehicle in a rough terrain setting similar to the rough terrain zones at our current US military locations. From this data, we would be able to more accurately define how a vibration test equates to the amount of vibration actually seen by these vehicles overseas. More information on this subject was included to the latest revision of Military Standard 810G (MIL-STD-810G) in the section labeled “Method 527.” This testing method is a generic description of the procedure and theory of Road Load Data Acquisition (RLDA) techniques. We have reviewed this material, and have experience in vibration testing that will aid us in the development of such simulation tests.