Hydrodynamic ram analysis of aircraft fuel tanks with different composite T-joint designs

摘要

Three different composite T-joint designs were investigated experimentally and numerically for application in fuel-filled wing tanks under hydrodynamic ram (HRAM) loads. The test campaigns covering 0° T-pull and 30° T-bending tests were conducted under quasi-static and high-rate dynamic conditions in order to assess potential strain rate effects on the failure behaviour. In addition to the experimental test campaign, numerical modelling with the explicit finite element code LS-Dyna was conducted with the models being validated against the test results and being applied to ballistic impact simulations of a composite fuel-filled tank structure. While the unreinforced baseline design showed a rather brittle behaviour and poor performance, significant residual strength improvements and structural integrity under HRAM loads could be obtained with a hybrid design with metallic, arrow-shaped z-reinforcements between the composite laminates of skin and spar. A promising macro modelling approach for an efficient representation of the T-joint failure behaviour in large models was derived and successfully applied to structural HRAM simulations.