Frequency Analysis of a rotating shaft

Frequency Analysis of Rotating Shaft

AIM:

The main objective of this study is to perform frequency analysis on Rotating Shaft

INTRODUCTION

Rotating shafts tend to bow out at certain speeds and whirl in a complicated manner. Whirling is defined as the rotation of the plane made by the bent shaft and the line of centers of the bearings. The phenomenon results from such various causes as mass unbalance, hysteresis damping in the shaft, gyroscopic forces, and fluid friction in bearings. Figure below shows a shaft with a wheel of mass m. The center of mass, G, of the wheel is at the distance e (eccentricity) from the center of the wheel, A. The shaft rotates with a constant (angular) speed Ω = p = const. The centrifugal force is F_c = mep² and acts at the center of mass, G. By projecting the centrifugal force on the horizontal (Ox) and the vertical axis (Oy) , the following relations are obtained:

Since the shaft has distributed mass and elasticity along its length, the system has more than one degree of freedom. One can assume that the mass of the shaft is negligible and its lateral stiffness is k. In this case the natural frequency is

MODEL IN SOLIDWORKS

PROPERTIES OF FREQUENCY ANALYSIS

After doing bearing fixture to the ends of Rotating shaft, perform a fine mesh. Click on results and wait.

BEARING FIXTURE

RESULTS

MODE_1

MODE_2

MODE_3

MODE_4

MODE_5

FREQUENCY RESONANCE PROPERTIES

S-N CURVE

From the above frequency resonance results, it is clear that when a part is designed it should avoid the above frequency analysis because it might effect the complete assembly.