Investigation of static and dynamic failure behaviour of composite T-joints

An experimental and numerical study of the failure behaviour of composite T-joints under quasistatic and high-rate dynamic loads is presented, including the investigation of different joint designs to increase damage tolerance and failure resistance. Three different T-joint designs using the same carbon fibre composite base material were used in this study. Two pure composite solutions and a hybrid design with arrow head-shaped metallic reinforcement pins in the through-thickness direction are presented. Specimen manufacturing and testing is 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 strain rate effects. The hybrid solution with the pin-reinforcement showed significantly increased post-damage load levels and energy absorption with the pins being pulled out of the laminate under large global deformations. The utilisation of a modern toughened epoxy resin in comparison to a conventional untoughened resin also showed significant improvements. In addition to the experimental test campaign, numerical simulations with the explicit Finite Element code LS-DYNA were conducted on micro, meso and macro level. The models were validated against the test results and applied to a ballistic impact simulation of a composite fuel tank structure under hydrodynamic ram loading.