Crash Impact Characteristics of Helicopter Composite Structures 830749

This paper describes the results of a research program to investigate the crash impact behavior of helicopter composite structures designed to meet the U.S. Army’s crashworthiness requirements specified in MIL-STD-1290. The program included design, fabrication, and crash testing of two full-scale composite helicopter cabin sections. The drop test conditions for the two cabin sections were representative of the 42 ft/s vertical crash impact velocity requirement specified in MIL-STD-1290 assuming the landing gear had slowed the aircraft from 42 ft/s to 30 ft/s prior to fuselage contact. Roll attitudes of 0° (flat) and 20° were used in the two cabin drop tests. Test results from both drop tests indicated that the strong protective shell structure around the occupants remained intact; structural deformation was restricted to the areas designed to crush and absorb energy; and most important, the excellent post-test condition of the cabin protective shell structure and the performance of specially designed energy-absorbing components demonstrated that the Army’s crashworthiness requirement could be met by a composite structure. The KRASH computer program was used for the crash impact analysis of the cabin sections. Load-deformation characteristics of key energy-absorbing components were derived from design support test data and used as input to the KRASH analysis. Based on the good crash impact performance of the composite cabins and the comparison of analytical and test results, KRASH proved to be a useful and reasonably accurate analysis tool for the design of helicopter composite structures to meet the Army’s crash-worthiness requirements.


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