Model-based evaluation of experimental modal analysis methods for multi-axis base excitation

Abstract

The multi-axis shaker is often used for the dynamic qualification of aerospace structures. The vibration test data can also be used for extracting of modal parameters like eigenfrequencies, mode shapes and damping. This thesis presents such identification method called ISSPA (Identification of Structural Systems Parameters) that disregards the unsolicited motions of the shaker during the vibration test. These unwanted motions are the consequence of the interaction (cross-talk) between the shaker and the test structure. To understand a dynamic behaviour of the test structure because of cross-talk effects a 3D demo structure is programmed with MATLAB and simulated in the frequency domain. The ana-lytical acceleration responses and geometry properties of the demo structure are retained as input data to check the ability of the ISSPA that is implemented in MATLAB. Finally, the identification proce-dures are applied to the real vibration test data of an aircraft section in order to identify the modal pa-rameters that can be used for the validation of analytical models.