Original Date: 08/08/1994
Revision Date: 01/18/2007
Information : Loose Cargo Simulation
CSTA developed a new standard for ensuring consistent loose cargo packaging testing on similar test equipment of varying size. The test variation in testing was discovered during a packaging qualification test on grommets by the Army Research and Development Engineering Center (ARDEC) to protect the rotating bands of the 105mm projectile during transportation. The packaging test was developed to simulate loose projectiles in the bed of a tactical wheeled vehicle.
During the loose cargo lab testing at CSTA, it was noted that the rotating bands on the 155mm projectile were being damaged by the failure of the grommets to remain secure over the rotating bands. These results did not match the results obtained by ARDEC during the development of the grommet design. Consequently, CSTA placed loose grommeted projectiles in an instrumented tactical vehicle to evaluate the actual field effects on the ammunition. This evaluation demonstrated damage similar to the original CSTA lab test.
Following these results, a wireless environmental data recorder was placed in the packaging tester to gather data on the dynamic characteristics of the test equipment. The data recorder has the advantage of being hand portable and self-contained with the ability to measure tri-axial acceleration. The measurements were taken several times to ensure a good presentation of the loose cargo test equipment at CSTA. After the baseline was established for the large packaging tester at CSTA, the same baseline establishment was performed on the small test equipment at ARDEC. The dynamic characteristics at ARDEC did not duplicate those generated at CSTA. This helped to explain why different results were obtained at CSTA when compared to ARDEC's development results. By increasing the Revolutions Per Minute (RPM) input into the ARDEC equipment, a similar dynamic output to the CSTA equipment was achieved. For a setting of 300 RPM on the CSTA tester, a setting of 320 RPM on the ARDEC tester was needed to duplicate a similar output. Three hundred RPM was selected because 20 minutes at 300 RPM on the CSTA equipment simulates 150 miles of loose cargo transported in a tactical wheeled vehicle.
Working with data from the U.K. and past U.S. data, modifications to the basic loose cargo test procedure were made. The test bed was changed from plywood to steel for all test objects, and new algorithms were derived for the computation of the test bed size to account for non-slender (defined as the ratio of the length to the diameter) test objects.
These modifications have been presented to the NATO STANAG 4370 and MIL-STD-810F working groups (ATC is an active member in both) and were incorporated in the next revisions. The modifications will also be proposed for ITOP 4-2-602.
In making these improvements, CSTA continues to ensure that only safe designs pass though CSTA testing. These types of improvements provide worldwide recognition to CSTA as a leader in transportation and vibration testing.
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