Frequency Analysis of a rotating shaft

Frequency Analysis of a rotating shaft

Aim: To model the provided compound with suitable dimensions and to perform a frequency analysis to obtain the five resonant frequencies in which the compound fails.

Natural frequency

Natural frequency is the frequency at which a body vibrates when it is disturbed. Each body has its own discrete set of frequencies at which the body vibrates when the body is disturbed. These sets of frequency depend on the size, shape and material properties of the body disturbed.

The example of natural frequency vibration of a body can be understood by a concept when a glass cup is filled with water at certain level and when the outer round edge of the glass is rubbed with some water, the glass starts to vibrate due to which a sound is made by the glass at certain pitch thus now we can say that the glass has vibrated at certain frequencies, the frequency at the which the glass vibrated also depends upon the amount of water inside and also the material properties. Hence if we change the amount of water present inside the glass, the set of vibration frequencies obtained will vary.

Forced frequencies

As in natural frequencies when the body is disturbed but if the it is by an external force then the body sates to vibrate on certain frequencies depending upon the forced applied this frequency at which the body vibrates is known as forced frequencies. If this frequency is less than the natural frequency of the body then the body will be normal but if the forced frequency exceeds the value of natural frequency of the body then the body will stat to collapse and get failed, this frequencies at which the body collapses is known as resonant frequencies.

Objective of the project

• To model the compound flywheel with rod as shown with suitable dimensions which suits well.
• To perform a frequency analysis on the model to with the bearing face fixed.
• To obtain the five resonant frequencies at which the body fails due to vibration.
• To obtain the chat of amplitude at all five resonant frequencies.

Body

The fly wheel with the rod is designed with suitable dimension to acquire the model as shown.

The diameter of the rod is 100 mm.

The the road is extruded to a length of 1000 mm with reffernce to mideplane option.

The diameter of the end bearing face is 75 mm and they are extruded to a length of 50 mm.

At the center of the road the flywheel is drawn with a circle of dia 500 mm and they are extruded with the midplane option for 50 mm.

The body is fixed at faces were the bearings will be placed.

The body is meshed to the fineness of 13 mm.

Resonant frequency

The result is set to obtain five set of amplitude of resonance frequency results.

Conclusion: From the above analysis we should make sure that the working fequency at which the model vibrates when this model is fixed to some machine should not exceed these five Resonance frequency in prevent the model from getting failed.