SIMULATION OF THE IMPACT ON GROUND OF AIRDROP LOADS TO DEFINE A STANDARD WORST CASE TEST

The French Flight Test Centre in Toulouse (CEV Tl) made in 2004 prototype simulations of ground impact after airdrop (2d-40, 5th European LS-DYNA users conferences.) Its purpose was to enable the test centre to achieve parametric analyses of the shock level produced by airdrop with a combination of simulation and real tests, which was not feasible with tests only (because of the number of test cases required). Indeed a first proposal with several hundreds test cases had been rejected by the French Army Headquarters because of its high cost and length. An alternate solution with about a hundred simulation results and fifty four life tests was finally accepted and realised throughout 2005 and 2006. LS-DYNA was used to demonstrate what were the cargo fitting techniques and impact conditions that could produce the highest shock levels with the current state of airdrop technology. This gave the experts early hints in their purpose to design a standard test case to assess weapon systems reliability after airdrop. The testing campaign afterwards was focused on checking key points of the simulation analysis and evaluate the importance of non deterministic effects that could not be simulated, which is needed to estimate the actual value of the future standard qualification test for airdrop.