Frequency Analysis of a rotating shaft

Aim: Frequency Analysis of a rotating shaft

Objectives :
1. To create 3D model of a rotating shaft.
2. To perform frequency analysis on the rotating shaft and nd out the critical frequencies.

Introduction:
The resonant frequency is the oscillation of a system at its natural or unforced resonance. Resonance occurs when a system is able to store and easily transfer energy between different storage modes, such as Kinetic energy or Potential energy as you would nd with a simple pendulum.

Resonance - "The increase in the amplitude of oscillation of an electric or mechanical system exposed to a periodic force whose frequency is equal or very close to the natural undamped frequency of the system."

Mode:
The mode is a statistical term that refers to the most frequently occurring number found in a set of numbers. The mode is found by collecting and organizing data in order to count the frequency of each result. The result with the highest count of occurrences is the mode of the set, also referred to as the modal value.
Mode Shapes The deformed shape of the structure at a specic natural frequency of vibration is termed its normal mode of vibration. Some other terms used to describe the normal mode are mode shape, characteristic shape, and fundamental shape. Each mode shape is associated with a specic natural frequency.
Modes are inherent properties of a structure and are determined by the material properties (mass, damping, and stiffness), and boundary conditions of the structure. Each mode is dened by a natural (modal or resonant) frequency, modal damping, and a mode shape.

For creating the model

1. create the 2D sketch for shaft
2. create the 3d shaft by revpolve feature

For Analysis

1. Select the frequency study
2. Apply the material to the rotating shaft
3. Selection of fixtures : bearing fixture is selected
4. Meshing
5. Run the study
6. modes are created

dimension

3d model

selection of material:

Meshing:

Results:

Mode 1

Mode 2

Mode 3

Mode 4

Mode 5

list of modes

Plot : frequency vs modes