Recent content by Lisa Jones

  1. L

    Vibration of beam with bump test

    Thanks for your help. The bump test was performed by displacing the free end of the beam by hand, and then letting it oscillate naturally. The fixed end is properly fixed. The sampling rate was very high - no aliasing problems that I can see. The peaks are perfect multiples of the 6.75...
  2. L

    Vibration of beam with bump test

    Hi, HARMONICS! I have discovered that the frequencies are at exactly 1 times, 3 times and 5 times the 7Hz signal. There is also a small bump at 7 times! This leads me to think the mass of the accelerometer has reduced the natural frequency from 10Hz to 7Hz, and then the other peaks are...
  3. L

    Vibration of beam with bump test

    Hi, I need some help with an experiment: I have a cantilevered steel beam, fixed at one end and free at the other. When I excite the beam with forced vibration at the fixed end, resonant frequencies are evident. The first is at 10 Hz and the second is at 60Hz. Performing analytic...
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