Abstract
Impact vibration of beam that has very narrow clearance between beam and impact wall, and that is excited around 2nd natural frequency, was investigated and the followings are made clear. (1) The beam is weakly resonant if excitation frequency is nearly equal to even number times the 1st natural frequency. (2) Even if the excitation frequency is nearly equal to the 2nd natural frequency, the beam is not resonant because 1st mode is dominant the vibration. (3) Those are caused by asymmetric property of the system. Furthermore, the beam is strongly resonant at non natural frequency.
