Numerical analysis of the hydrodynamic ram of a CFRP integral tank

Abstract

The vulnerability of a CFRP integral tank against HRAM (hydrodynamic ram) is analysed. The geometry of the tank is based on a generic MALE (Medium Altitude Long Endurance) UAV (Unmanned Aerial Vehicle). Several design-improvements are to be analysed. HRAM occurs if a high-energetic object penetrates a fluid filled structure (e.g. a fuel tank below its fill level). Pressure waves, originating from the impactor, cause severe pressure loads on the walls. This can lead to the destruction of the tank and in case of an integral tank, to the failure of structural necessary components. One segment of the integral tank from the generic MALE-wing is simulated using the explicit finite element code LS-DYNA with Fluid-Structure-Interaction. The analysed design-solutions include spars with holes in it that should work as pressure outlets and a redesign of the outer spar.