EVALUATION OF LOAD-TIME FUNCTIONS DUE TO IMPACT OF SOFT MISSILES

The threat spectrum of safety related structures has severely changed since September 11, 2001. The deterioration capability of large aircrafts impacting on structures has become aware in a dramatic manner. Simplified calculation models for aircraft impact are available but have not been verified for large commercial aircrafts. Based on this background, experimental studies are performed at the Materials and Testing Research Institute (MPA) Karlsruhe of the Universitat Karlsruhe (TH) to examine the shape and the peak loads of load-time functions induced by an impacting soft missile with a mass and stiffness distribution along the missile's axis similar to a commercial aircraft onto a rigid target. Different levels of water filling for simulating the kerosene tanks can be realised to investigate their influence on the load-time function. The characterisation of the major impact phenomena and their variation due to changing test parameters is the foremost goal of these experiments. The missiles are accelerated up to the impact velocity using an air-pressure gun. Impact forces are measured with a piezoelectric measuring platform as well as with accelerometers positioned on the target. The impact is filmed using a high-speed video camera. The experimental setup, measurement results and their evaluation will be presented in detail. The experimental study forms the reference for accompanied numerical calculations using the explicit finite element code LS-DYNA. Thus, a numerical model validated on the experiments shall be generated in order to provide an enhanced confidence level for the future calculation of real impact scenarios. First simulation results will be shown and briefly compared to the solution using the Riera method. A possible enhancement of this analytical method based on the experiments is beyond the scope of the project.