Support of Impact Testing with Instrumented Target Support by Finite Element Analysis

Kurzfassung

High Velocity Impact (HVI) testing is an important issue for aircraft certification. Particularly, bird strike is an impact incident with one of the highest kinetic energy an aircraft can experience. To reduce the cost of extensive gas gun testing for new aircraft structures there is growing interest in finite element (FE) simulations of impact damage. However, HVI simulations are not yet fully accepted by aviation authorities as a means of compliance. In order to validate the computational procedures reliable quantitative data are required from gas gun tests for detailed comparison with FE predictions. In order to prepare and validate expensive and complex experiments, numeric simulations are intended. Hence, FE models of a test setup are defined then used for impact analysis. Emphasis is set on studying the test setup, the structure as well as the model parameters. The test setup is an instrumented target support (ITS) which is designed to measure impact pulses by an internal strain bar. In contrast to surface strain gauge measurements applied on sensitive areas of a structure, the strain gauges are applied to the support bars which guide the impact strain pulses assuming uniaxial wave propagation. Thus, structural deformation is not monitored locally but quantitative measurements of dynamic load pulses acting on structures during gas gun tests are intended. Here, test results of bird pulse measurement with the ITS are evaluated and used to correlate with simulations. The test setup is created as a parametric geometry and impact analysis is performed with LS-DYNA.