Scribd
Upload
703 views3 pages

To Determine Natural Frequency of Torsional Vibration in Two Rotors System

This document describes an experiment to determine the natural frequency of torsional vibration in a two rotor system. Two discs of different masses are attached to a shaft and allowed to oscillate freely. The time for a set number of oscillations is recorded with different mass configurations. This data is used to calculate the theoretical and experimental periods and frequencies, which are then compared. The goal is to experimentally determine the natural frequency and validate it against theoretical calculations.

Uploaded by

muralidharan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
703 views3 pages

To Determine Natural Frequency of Torsional Vibration in Two Rotors System

This document describes an experiment to determine the natural frequency of torsional vibration in a two rotor system. Two discs of different masses are attached to a shaft and allowed to oscillate freely. The time for a set number of oscillations is recorded with different mass configurations. This data is used to calculate the theoretical and experimental periods and frequencies, which are then compared. The goal is to experimentally determine the natural frequency and validate it against theoretical calculations.

Uploaded by

muralidharan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
You are on page 1/ 3

TO DETERMINE NATURAL FREQUENCY OF TORSIONAL

VIBRATION IN TWO ROTORS SYSTEM

AIM:
To determine the period and frequency of torsional vibration of the two rotor
system experimentally and compare it with the theoretical values

APPARATUS REQUIRED:

 Shaft
 Spanner
 Chuck key
 Stop Watch
 Measuring Tape
 Weights and cross arms

DESCRIPTION OF THE SETUP:

Two discs having different mass moment of inertia are clamped one at each end
of shaft by means of collet. Mass moment of inertia of any disc can be changed by
attaching the cross lever with weights. Both discs are free to oscillate in the ball
bearings. This provides negligible damping during experiment

FORMULAE:

Experimental period of vibration , T exp = tm / n , sec


Where,
tm = mean time taken for n oscillations
n = number of oscillations = 5
Theoretical period of vibration , T theo = 2π { sqrt [(IA IB) / Kt(IA + IB)] }, sec
Where,
Moment of inertia of disc A, IA = mA ( DA2 / 8 ) , Nms2
Moment of inertia of disc B, IB = mB ( DB2 / 8 ) , Nms2

New No. 3, Old no. 2, S.V . Koil Street, Sekar Nagar, Ashok Nagar, Chennai – 600 083
Phone: +91 (044) 4352 1779 | Cell: (+91) 9789976777, 9789975777& 9940077338
Email: sales@elshaddaiengg.com, support@elshaddaiengg.com www.elshaddaiengg.com
Torsional stiffness, Kt = ( G Ip ) / L , Nm
Where,
G = modulus of rigidity of the shaft, N/m2
L = length of the shaft between discs, m
Polar moment of inertia, Ip = ( π / 32 ) d4 , m4
Where,
d = shaft diameter, m
Experimental frequency of vibration, F exp = 1 / T exp , Hz
Theoretical frequency of vibration, F theo = 1 / T theo , Hz

PROCEDURE:

1) Fix the discs A and B to the shaft and fit the shaft in bearing.
2) Deflect the discs A and B in opposite directions by hand and release.
3) Note down the time required for n = 5 oscillations.
4) Fit the cross arm to the disc A and attach equal masses to the ends of cross arm and
again note down time.
5) Repeat the above procedure with different equal masses attached to the ends of cross
arm.

OBSERVATION:

Diameter of the disc A , DA = 250 , mm


Diameter of the disc B , DB = 250 , mm
Mass of the disc A, mA = 3.3, kgf
Mass of the disc B, mB = 1.74, kgf
Modulus of rigidity of the shaft, G = 0.35 x 1011, N/m2
Shaft diameter, d = ----- mm
Length of the shaft between discs, L = ---- m
Mass of the cross arms with bolts and nuts = 0.725

New No. 3, Old no. 2, S.V . Koil Street, Sekar Nagar, Ashok Nagar, Chennai – 600 083
Phone: +91 (044) 4352 1779 | Cell: (+91) 9789976777, 9789975777& 9940077338
Email: sales@elshaddaiengg.com, support@elshaddaiengg.com www.elshaddaiengg.com
TABULATION:

S.No Length Of No. Of Time Tth Texp Fth Fexp


Shaft Oscillation
1.

2.

3.

4.

RESULT:

The natural frequency of the torsional vibration in two rotor system is -----Hz

New No. 3, Old no. 2, S.V . Koil Street, Sekar Nagar, Ashok Nagar, Chennai – 600 083
Phone: +91 (044) 4352 1779 | Cell: (+91) 9789976777, 9789975777& 9940077338
Email: sales@elshaddaiengg.com, support@elshaddaiengg.com www.elshaddaiengg.com

You might also like