Failure behaviour of composite T-joints with novel metallic arrow-pin reinforcement

An experimental and numerical study of the failure behaviour of composite T-joints under quasi-static and high-rate dynamic loading is presented, focusing on the investigation of a novel reinforcement technique in the through-thickness direction using metallic arrow-pins to increase failure resistance and damage tolerance. Specimen manufacturing and testing are described in detail. 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 loading rate effects. The novel concept with the arrow-pin reinforcement showed significantly increased post-damage load levels and energy absorption capability with the pins being pulled out of the laminate under large global deformations. In addition to the experimental test campaign, numerical simulations with the explicit finite element code LS-Dyna were conducted on local, global and macro-modelling level. The models were validated against the test results and applied to ballistic impact simulations of an exemplary composite fuel tank structure under hydrodynamic ram loading, where the novel joint design led to significantly higher damage resistance.