50 B. Weekes and D. Ewins Fig. 5.6 UB100X-B accelerometer test geometry from (a) automated DOF placement using normalised modal displacement and DOF reduction using MAC, (b) operator intuition Pre-Test Reduced FE Mode 27: 246.440 Hz Mode 26: 232.590 Hz Mode 25: 209.430 Hz Mode 24: 207.410 Hz Mode 23: 200.330 Hz Mode 22: 192.120 Hz Mode 21: 188.580 Hz Mode 20: 178.160 Hz Mode 19: 175.460 Hz Mode 18: 163.840 Hz Mode 17: 162.850 Hz Mode 16: 145.850 Hz Mode 15: 143.270 Hz Mode 14: 141.530 Hz Mode 13: 139.550 Hz Mode 12: 136.870 Hz Mode 11: 134.700 Hz Mode 10: 117.810 Hz Mode 9: 111.890 Hz Mode 8: 111.280 Hz Mode 7: 108.260 Hz Mode 6: 104.560 Hz Mode 5: 95.134 Hz Mode 4: 78.799 Hz Mode 3: 67.854 Hz Mode 2: 35.425 Hz Mode 1: 32.641 Hz 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Pre-Test Reduced FE Mode 27: 246.440 Hz Mode 26: 232.590 Hz Mode 25: 209.430 Hz Mode 24: 207.410 Hz Mode 23: 200.330 Hz Mode 22: 192.120 Hz Mode 21: 188.580 Hz Mode 20: 178.160 Hz Mode 19: 175.460 Hz Mode 18: 163.840 Hz Mode 17: 162.850 Hz Mode 16: 145.850 Hz Mode 15: 143.270 Hz Mode 14: 141.530 Hz Mode 13: 139.550 Hz Mode 12: 136.870 Hz Mode 11: 134.700 Hz Mode 10: 117.810 Hz Mode 9: 111.890 Hz Mode 8: 111.280 Hz Mode 7: 108.260 Hz Mode 6: 104.560 Hz Mode 5: 95.134 Hz Mode 4: 78.799 Hz Mode 3: 67.854 Hz Mode 2: 35.425 Hz Mode 1: 32.641 Hz Fig. 5.7 AutoMAC matrix for the prototype test geometry on UB100X-B shown in Fig. 5.6b geometry with the same pattern of DOFs applied to each panel surface was manually-defined in the virtual test software, as shown in Fig. 5.6b. This geometry was found to give minimal aliasing of the mode shapes over the frequency range 0– 250 Hz (see autoMAC matrix, Fig. 5.7), and the modes which correlate due to aliasing are observed to occur at dissimilar frequencies.
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