32 Material Characterization of Gyroscope Isolator Using Modal Test Data 349 0 500 1000 1500 0 0.5 1 1.5 2 2.5 3 3.5 FRFs relating input and output acceleration frequency [Hz] Point 1 Point 2 Point 3 Point 4 Fig. 32.12 Transfer functions obtained from the sweep tests of gyroscope B, no washers 0 500 1000 1500 0 1 2 3 4 5 6 7 8 9 10 FRFs relating input and output acceleration frequency [Hz] Point 1 Point 2 Point 3 Point 4 Fig. 32.13 Transfer functions obtained from the sweep tests of gyroscope B, with washers 32.6 Conclusion A study performed to obtain material characteristics of an isolation layer in a gyroscope is presented. The material is accepted to be orthotropic and modeled accordingly. Young’s and shear moduli are determined through an optimization procedure so that the modal test results and FEM modal analysis results match each other. During the procedure it was observed that the boundary condition in the FEM is conceptually different than the actual test rig. In order to overcome this inconvenience, the connection of the test rig is modified and the modal tests are updated. Effect of the details of fixing a test structure to a foundation on modal test results is shown through this observation. Damping property of the material is determined by seeking the response of the structure at the dominant mode frequency. Identified material properties are employed in FEM of another gyroscope with the same isolation layer. Modal tests are performed on this gyroscope as well and the results are compared to FEM modal analysis results. The results have revealed a certain degree of error at each natural frequency, whereas the mode shapes came up in the same order. In addition, sweep tests performed of the second gyroscope are performed. Transfer functions relating the acceleration at the measuring point and the acceleration load are presented. Sweep tests are carried out with both boundary conditions and the difference between the FRF sets are observed.
RkJQdWJsaXNoZXIy MTMzNzEzMQ==