Advanced Test Strategy for Identification and Characterization of Nonlinearities of Aerospace Structures

The development of new, high-performance aerospace structures requires the availability of powerful and efficient methods for dynamic testing. Also, the European aircraft industry is calling for a reduction of the testing times for prototypes without diminishing the accuracy of the test results. As a consequence, substantial improvements in the test strategy of ground vibration and modal survey tests have been developed and applied during the last years. In addition, space agencies like the European Space Agency are interested in advanced measurement techniques, for example, when a spacecraft has to be qualified by a boosted modal survey test. Very high loads are introduced in the structure during these tests, and significant nonlinear behavior of the spacecraft can sometimes be observed. A test strategy is presented that can be used to identify and characterize nonlinear, structural behaviour during modal testing. The method assumes a weak non-linear behavior and operates in modal space. The approach can replace the common analysis by linearity plots that are utilized during modal survey testing of aerospace structures. The proposed strategy supplies much more information on the nonlinear behavior than the common procedure and allows for a reduction in the test duration.