On the Characteristic Frequency of the Transverse Vibration of a Portable Rotary Cutter with an Electric Motor (IV)

Abstract

In order to develop the analysis of vibration for portable rotary cutters, natural frequencies were calculated using the following simplified model. The model chosen consists of freely suspended beams which are connected with each other at 5 points by springs. The first beam of them has 5 mass on it, and the second one is uniform.
The calculation procedures used are the Myklestad method (A), transfer matrix method for nummerical analysis (B) and transfer method for analytical analysis (C). Results obtaind are as follows:
(1) Linear spring rate greater than about 500kg/cm affected little on the secondary natural frequency and these natural frequencies were very near from those of similar model in which two beams were connected by suporting points instead of springs.
(2) When the linear spring rate is very high the calculation errors by electronic computor grow great and it may be impossible to solve simultaneous equations at last stage of these calculations.
(3) As for calculation time, A method was least and B method was greatest in this case. These calculation methods seem to be very convenient, like finite element method, for models which consist of complicated beams.