Desenvolvimento de uma técnica experimental de análise modal sem contato via excitação acústica

Abstract

In the aeronautical industry, ground vibration tests are essential for determining the dynamic behavior of structural components. This information assists in the validation and improvement of models used in various stages of design, especially in aero elastic calculations. Among other functions, these models predict the natural frequencies and modal shapes of the structures concerned. The most common methods use an electrodynamics shaker to excite the structure. The use of this type of equipment can cause problems in the quality of the data acquired as wellas damage the test structure. This work presents the development of a methodology for noncontact excitation by means of acoustic waves. Validation tests have been developed with a composite material plate with known vibrational behavior. These tests were finite elementanalysis, modal analysis and acoustic excitation tests. After the validation, the technique was used to test the wing of the CEA 311-Anequim aircraft. The test results were compared with results of finite element models. The technique has shown itself able to excite the modes in the region of interest and provide values for frequency and modal forms consistent with the dynamic model.