On the Characterestic Frequency of the Transverse Vibration of a Portable Rotary Cutter With an Electric Motor. (Part 1)

Abstract

The transverse vibration of a portable rotary cutter stem with an electric motor was measured under freely suspended condition.
Characterestic frequencies of flexural vibration were also calculated using three simplified vibration models:
(A) A simply Supported beam.
(B) A free beam with concentrated mass at its each end.
(C) A free beam with one concentrated mass at one end,
and three concentrated mass at the other end (motor assembly's end).
Results obtained are as follows;
(1) Tow characterestic frequencies were found in the rotational velocity range, and the secondary one seemed to be important in practical operation.
(2) The acceleration measured was rather great even at velocities far from those charactrestic frequencies, in spite of their small amplitudes.
(3) The difference between the frequencies by calculation and the experimental data was as follows;
Model first freq. second freq.
A -8% 12%
B 7% 17%
C 2% 4%
(4) The numerical calculation procedure seemed to be one of the best ways for determing characterestic frequnencies of portable rotary cutters by improving there models.