A Review of Experimental Modal Analysis Methods with respect to their Applicability to Test Data of Large Aircraft Structures

Kurzfassung

In this paper, different modal analysis tools are investigated with respect to their applicability to test data from ground vibration tests (GVT) of large aircraft. Three different modal analysis methods are investigated. These are the Frequency Domain Direct Parameter Identification (FDPI), the Least-Squares complex Exponential method (LSCE), and the Least-Squares Complex Frequency Domain method (LSCF or Poly MAX). Test data from GVT of a large aircraft usually have features like noise contamination and weak non-linearity of some modes. Thus, the influence on the results of experimental modal analysis of statistical errors (such as noise) and systematic errors (such as non-linearity) in the FRFs are investigated. Simulated FRFs of an analytical system contaminated with different levels of artificial noise are used to study the influence of statistical errors, whereas simulated non-linear FRFs obtained from an analytical system with a friction-type non-linearity is used to study the influence of systematic errors. In addition, the aforementioned modal analysis methods were applied to a dataset acquired during the GVT of the Airbus A380. The modal analysis results obtained with the different analysis methods are compared and evaluated based on the results of the analytical study of the influence of statistical and systematic errors.