Effects of Support Conditions and Shaker Arrangements in Beam Vibration Testing

摘要

The motion of a uniform beam is studied directly and with the aid of an analog computer, in order to determine the effects of support damping in terms of an approximate per cent of critical damping in each mode. The computer is used to determine the range of support damping for which velocity coupling can be neglected in calculating the damping in the constrained modes. Curves are also presented giving the relative amplitudes of the first few constrained modes and the first few free-free modes plotted as a function of shaker position for three 'soft-mounted' conditions. Similar curves are given for an actual missile. Recommendations are made concerning procedures to be used when ground-testing a missile for the damping in each of its free-free modes. (Author)