35 Project-Oriented Validation on a Cantilever Beam Under Vibration Active Control 357 Fig. 35.2 FE model of the cantilever beam with one fixed end Fig. 35.3 FE model of the cantilever beam with one fixed end and rubber springs Fig. 35.4 FE model of the cantilever beam with electromagnetic actuator 35.2.2 EMA and Modal Frequency Error Estimation of the Cantilever Beam with One Fixed End 35.2.2.1 Experimental Modal Analysis A cantilever beam test-bed and the equipments including HP35670A dynamic signal measuring-analyzing instrument, the PCB’s force acceleration sensor and a U333A31 acceleration sensor are used in experiment modal testing and analysis. One electromagnetic exciter was employed by using the sweep sine force; The Fig. 35.5 shows cantilever beam and the main test equipments. There are three tests of state. One is only a cantilever beam, and another one is the cantilever beam with two rubber springs, the last one is the cantilever beam with electromagnetic actuator (supporting). The experiments adopt 1 acceleration sensor and 18 measuring points, 1,600 spectral lines and the all mode are measured within 5–405 Hz or 40–440 Hz. The testing FRF are showing in Fig. 35.6 of the two states. By using RFOP method providing from Nmodal software developed by Nanjing University of Aeronautics and Astronautics, the modal parameters identification are performed. 35.2.2.2 Modal Frequency Errors Estimation of the Cantilever Beam with One Fixed End After the EMA of this cantilever beam with one fixed end, the modal frequency errors of the FE model were computed by Eq. 35.2. See Table 35.1.
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