tailieunhanh - Vibration Analysis and Control New Trends and Developments Part 5

Tham khảo tài liệu 'vibration analysis and control new trends and developments part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 90 Vibration Analysis and Control - New Trends and Developments Fig. 15. Root locus of the total transfer function Gt for CAFC on the footbridge x pole o zero F footbridge A actuator Active Control of Human-Induced Vibrations Using a Proof-Mass Actuator 91 Uncontrolled m s2 Controlled m s2 Reduction Mass displacement m Walking at Hz 89 Running at Hz 40 Table 3. Simulation performance assessment for the footbridge using the peak acceleration for walking and running excitation Walking and running tests are carried out to assess the efficacy of the AVC system. The walking tests consist of walking at Hz such that the first vibration mode of the structure Hz could be excited by the second harmonic of walking. A frequency of Hz is used for the running tests so that the structure is excited by the first harmonic of running. The walking running tests consisted of walking running from one end of Span 2 to the other and back again. The pacing frequency is controlled using a metronome set to 105 beats per minute bpm for Hz and to 210 bpm for Hz. Each test is repeated three times. Uncontrolled Controlled Reduction Walking at Hz Peak acceleration m s2 70 MTVV I m s2 67 Running at Hz Peak acceleration m s2 64 MTVV m s2 68 Table 4. Experimental performance assessment for walking and running excitation. Maximum Transient Vibration value defined as the maximum value of Is running RMS acceleration The results are compared by means of the maximum peak acceleration and the MTVV computed from the 1 s running RMS acceleration. Table 4 shows the result obtained for the uncontrolled and controlled case. It is observed that the AMD designed with a moving mass of 30 kg performs well for both excitations achieving reductions of approximately 70 . Fig. 16 shows the response time histories including the 1 s RMS uncontrolled and controlled for a walking test. Fig. 17 shows the same