Frequency Analysis of a rotating shaft

AIM:To find out the critical frequencies of a rotating shaft in Solidworks.

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 example: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 revolve feature

For Analysis

Step:1. Select the frequency study

Step:2. Apply the material to the rotating shaft

Step;3. Selection of fixtures : bearing fixture is selected

Step:4. Meshing

Step:5. Run the study

Step:6. modes are created

2D Drawing:

Applying revolve feature to easily make shaft in 3d:

Selected material properties.

Applied a bearing fixture on the stepped face of the rod at the two ends and perform the analysis.

Applied the mesh parameter on the model and started the simulation.

RESULTS:

MODE1:

MODE2:

MODE3:

MODE4:

MODE5:

FREQUENCY VS MODE PLOT:

output list:

CONCLUSION:

From different amplitude analysis, we found that

1.frequency varies for different mode shapes 2.amplitude is directly proportional to the frequency and the resonance.