BALLISTIC IMPACT ON A TRANSMISSION TAIL ROTOR SHAFT FOR HELICOPTER

For military rotorcraft, designed for low altitude profile mission in hostile environment, is fundamental to evaluate the damage of high critical components affected by ballistic impact. Actually numerical approach allows to simulate a very complex scenario involving impact phenomena. However, experimental tests still play a primary role. In this paper an experimental impact test of a 7.62 NATO projectile perforating a helicopter tail rotor shaft is presented. Test equipment includes a dedicated shaft support frame that allows the specimen positioning in order to set the worst operational conditions. Impact velocity, residual velocity and deflection of the projectile have been detected during the test. Residual stresses have been also measured near the impact zone. All the experimental activities were compared with numerical simulation of the impact, carried out by an explicit finite element code (ABAQUS/Explicit). The results show a good agreement between numerical and experimental data.